grassland bypass project annual report · grassland drainage area (gda) to the san joaquin river...

Prepared for the Grassland Bypass Project Oversight Committee

June 1999

U.S. Bureau of ReclamationU.S. Environmental Protection AgencyU.S. Fish and Wildlife ServiceU.S. Geological SurveyCentral Valley Regional Water Quality Control BoardCalfornia Department of Fish and GameSan Luis & Delta-Mendota Water Authority

Grassland Bypass ProjectAnnual ReportOctober 1, 1997 through September 30, 1998

Grassland Bypass ProjectAnnual Report

October 1, 1997 through September 30, 1998

Prepared for the Grassland Bypass Project Oversight Committee

June 1999

U.S. Bureau of ReclamationU.S. Environmental Protection Agency

U.S. Fish and Wildlife ServiceU.S. Geological Survey

Central Valley Regional Water Quality Control BoardCalfornia Department of Fish and Game

San Luis & Delta-Mendota Water Authority

Grassland Bypass Project Annual Report

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iii

Table of Contents

Table of Contents

Chapter 1: Summary ......................................................................................................................... 1

Chapter 2: Drainage Control Activities by Grassland Area Farmers .............................................. 13

Chapter 3: Grassland Bypass Project Flow and Salinity Monitoring .............................................. 25

Chapter 4: Water Quality Monitoring ............................................................................................ 47

Chapter 5: Biomonitoring Program for the San Luis Drain Discharge: Toxicity Studies ............... 61

Chapter 6: Biological Effects of the Reopening of the San Luis Drain to Carry SubsurfaceIrrigation Drainwater ...................................................................................................................... 91

Chapter 7: Selenium in Sediment ................................................................................................. 119

Chapter 8: Sediment in Drain ...................................................................................................... 127

Chapter 9: Quality Control ........................................................................................................... 131


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1

Chapter 1: Summary

Chapter 1

Summary

Bob Young, Technical Team LeaderU.S. Bureau of Reclamation


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IntroductionThe Grassland Bypass Project (GBP) completed itssecond year of operations on September 30, 1998. Thissecond Annual Report documents results from themonitoring efforts not only for water-year (WY) 1998but from the first year and in some cases from pre-Project data as well. One function of the Annual Reportis to document a tremendous amount of scientific dataand information so that it can be shared with all inter-ested parties. The purposes of this report are to buildupon our historic information (pre-Project or baselinedata), to begin the process of discerning changes inenvironmental conditions over time (Project data), and todocument Project findings to date.

During the year, GBP management held twopublic Oversight Committee (OC) meetings, eightTechnical Policy and Review Team (TPRT) meetings,twelve monthly Data Collection and Reporting Team(DCRT) meetings, held an informational researchworkshop, issued twelve monthly reports, four quarterlydata reports, four quarterly narrative and graphicalsummary reports, and two 1998 storm event reports.

This Annual Report is a compilation of technicalchapters prepared by the entities responsible for eachportion of the GBP.

Project AuthorizationThe U.S. Bureau of Reclamation (USBR) signed aFinding of No Significant Impact (FONSI) on Novem-ber 3, 1995 for use of a 28-mile segment of the San LuisDrain (SLD; U.S. Bureau of Reclamation, 1995). Thissegment conveys agricultural drainage waters from theGrassland Drainage Area (GDA) to the San JoaquinRiver via a 6-mile segment of Mud Slough (north). Amap of the GBP area and a schematic diagram arepresented in Figures 1 and 2. Analysis from an environ-mental assessment (EA) dated April 1991, and supple-mented in November 1995, resulted in the FONSI.

A Use Agreement (UA) was signed on November3, 1995 between USBR and the San Luis & Delta-Mendota Water Authority (SL&D-MWA; USBR andSL&D-MWA, 1995). The UA allows for the use of 28miles of the SLD for a two-year duration (WY 1997 and1998). The UA allows for renewal of this interim use forno more than three years if certain conditions are met.

During Project development, three primary areasof concern were identified by the public: (1) long termdrainage management, (2) potential adverse effects to

fish and wildlife, other environmental resources, andpublic health, and (3) concerns that appropriate actionswill be taken.

Approval of the GBP was granted with theunderstanding that certain benefits and risks wereassociated with the Project. Anticipated benefits include:

1. Agricultural drainage water will be removedfrom the Grassland Water District (GWD)delivery channels allowing refuge managers toreceive and apply all of their fresh waterallocations according to optimum habitatmanagement schedules.

2. Removal of agricultural drainage water from theGWD channels will reduce the seleniumexposures to fish, wildlife, and humans in thewetland channels and Salt Slough. Concentra-tions of salinity and other constituents may alsobe reduced within the wetland channels andSalt Slough.

3. Combining agricultural drainage flows within asingle concrete-lined structure, the SLD, allowsfor better monitoring, potentially leading to amore detailed evaluation and effective control ofselenium and agricultural drainage.

4. The establishment of an accountable drainageentity will provide the framework necessary forresponsible watershed management in theGrassland Basin.

These benefits are weighed against the potential risks:

1. Combining agricultural drainage flows withinthe SLD will result in an increase in seleniumand other constituents which are dischargedinto Mud Slough. These constituents will beabove the levels historically discharged to MudSlough and could have an adverse environmen-tal effect on six miles of Mud Slough.

To address these concerns and potential risks, theprogram description was modified to include actionsensuring that:

1. There is continued progress toward long-termresolution of drainage management issues.

2. There will be no significant adverse effects tofish and wildlife, other environmental resources,or public health.

3. All commitments will be implemented andadhered to as part of the GBP.

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Chapter 1: Summary

Study Area

Grassland BasinAgriculturalDrainage Area

Mendota Pool

San Joaquin River

Stanislaus River

Tuolumne River

Merced River

San Joaquin River

Vernalis

Crows LandingN

HG

F

D

Salt S

lough

Mud S

lough

Figure 1. Map of the Grassland Bypass Project


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North

Grassland

Water District

South

Grassland

Water District

Agricultural Water Districts

GrasslandBypass

Main Canal(via DMC andMendota Pool)

Camp 13Canal

J KAgathaCanal

A

Wetlandwatersupply

L

San Luis Canal MSanta Fe

Canal

SanLuis

Drain

Blake-PorterBypass

SaltSlough

F

Santa FeCanal

Fremont CanalSan Luis Canal

San Luis Drain

B

D

C

I

E

Mud Slough(north)

San Joaquin RiverG

H

N

Figure 2. Schematic Diagram Showing Locations of GBP Monitoring Sites

Relative to Major Hydrologic Features of the Study Area

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Chapter 1: Summary

1997–1998 HighlightsProject Gets Three-year Renewal

The Oversight Committee agreed on January 25, 1999that all conditions required for Project renewal had beenadequately met or addressed and recommended a 3-yearrenewal. The FONSI document for the GBP specifiesthat the UA may be renewed for up to 3 years, providedthat the following four conditions are met:

a. The Central Valley Regional Water QualityControl Board (CVRWQCB) adopts andimplements approvable Basin Plan amendmentsand implementation measures consistent withthe recommendations included in the consensusletter to the CVRWQCB dated November 3,1995.

Status: In May 1996, the CVRWQCB adoptedBasin Plan amendments governing agriculturalsubsurface drainage and is currently implement-ing those amendments. The amendments areconsistent with recommendations contained inthe November 3, 1995 consensus letter. Theamendments appear likely to meet the require-ments of the Clean Water Act, but have notbeen approved by the U.S. EnvironmentalProtection Agency (USEPA). USEPA willmake an official determination upon completionof Section 7 consultations with the U.S. Fishand Wildlife Service (USFWS). Taking thisstatus into account, the OC has agreed toconsider this condition as being met forpurposes of Section V.B. of the UA and therelated FONSI.

b. The CVRWQCB issues to the SL&D-MWAand the USBR waste discharge requirementsfor discharges from the SLD consistent withthe recommendations included in the consen-sus letter to CVRWQCB dated November 3,1995. The SL&D-MWA operates the SLD inaccordance with those requirements. USBR canwaive this requirement upon a finding that thefailure of the CVRWQCB to adopt andimplement such Basin Plan amendments andimplementation measures is due solely tofactors beyond the control of either theSL&D-MWA, the draining parties, orCVRWQCB.

Status: Completed—Waste Discharge Require-ments were issued July 24, 1998.

c. The SL&D-MWA agrees to the applicableloads specified in Appendix A of the November3, 1995 consensus letter to the CVRWQCB. Inaddition, the SL&D-MWA agrees thatattainment of such loads will be measured andreviewed under the process described in the UA,Section V.C.

Status: Completed—Incorporated in the wastedischarge requirements.

d. The draining parties develop a long-termdrainage management strategy and plan ofimplementation (Drainage Management Plan)consistent with the Basin Plan Amendment.Continued use of the SLD must be consistentwith this Drainage Management Plan and theBasin Plan Amendment.

Status: The Grassland Area Farmers (GAF)submitted a Drainage Management Plan onSeptember 30, 1998 to USBR and to theCVRWQCB. USBR distributed the DrainageManagement Plan for public review withcomments and suggestions requested to be sentto the GAF. It is anticipated that this Plan willundergo modification and refinement duringthe environmental documentation process,which will include public and agency input andreview, and evolve into the long-term project.

Declaration of “Unforeseeableand Uncontrollable” for WY 1998

Rain, rain, and more rain. The GBP’s second yearwitnessed El Niño’s impact. Large amounts of rainfall inthe GBP’s watershed, created large volumes of surfacerunoff and subsurface drainage. Monthly selenium loaddischarge values are presented in tabular form in Table 1and shown graphically in Figure 3. For the second year ina row, the GAF petitioned the OC for waivers ofexcessive drainage discharges based on the “unforeseeableand uncontrollable” articles within the UA.

The Use Agreement for the GBP establishes loadtargets for the amount of selenium that can be dis-charged by the SL&D-MWA from the GrasslandDrainage Area in any given month and over a full year(Table 2). The UA also contains incentive fees that apply


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Site B Discharges

Load Measured Storm Combined Subject to Percent Incentive

Month Value Discharge Discharges Discharges Exceedance Exceedance Fee

Se (lbs) Se (lbs) Se (lbs) Se (lbs) Se(lbs) percent $

October 348 248 0 248 0 na 0November 348 207 0 207 0 na 0December 389 178 0 178 0 na 0January 533 355 0 355 0 na 0February 866 965 350 1,315 0 na 0March 1,066 1,600 0 1,600 0 na 0April 799 1,554 0 1,554 0 na 0May 666 1,371 0 1,371 0 na 0June 599 807 0 807 0 na 0July 599 615 0 615 16 3 1,200August 533 500 0 500 0 na 0September 350 388 0 388 38 11 2,200

Monthly --- --- --- --- --- na 3,400Annual 6,660 8,768 350 9,118 na na na

Combined --- --- --- --- --- --- $3,400

Table 1. 1998 Incentive Fee Assessment, Grassland Bypass Project

when these targets are exceeded. The UA allows the OCto recommend waiver of the incentive fees, in whole or inpart, if a portion of the discharge is related to an “unfore-seeable and uncontrollable” event.

During the second year of the GBP (October 1,1997–September 30, 1998, WY 1998), the monthlyselenium load targets were exceeded seven times and theannual selenium discharge of 9,118 lbs exceeded the6,660 lbs annual load target value by 37% (2,458 lbs).

At the May 28, 1998 public OC meeting, the OCreceived information related to the flooding and unusu-ally heavy rainfall that impacted the GBP. Annualprecipitation and precipitation for the month of Februaryat Los Banos and Panoche 2W rain sites were thehighest in the 50-year record. From the GAF’s letter onJune 11, 1998 to USBR:

In accordance with the Agreement for Use ofthe San Luis Drain and the Finding of NoSignificance Impact for the Project, we arehereby requesting that water-year 1998 bedeclared unforeseeable and uncontrollable inrelation to drainage discharges caused byevents beyond the control of the GrasslandArea Farmers. The reason for this request isthe excessive rainfall that has occurred thisyear, which is the highest, or near the highestof record.

The OC on August 5, 1998 agreed in favor of the GAFand issued the following response:

You recently requested that water-year 1998be designated as “unforeseeable and uncon-trollable” under the provisions of the UseAgreement for the Grassland BypassChannel Project. The Technical and PolicyReview Team reviewed the supportingdocumentation included in the request andthe Oversight Committee has subsequentlydetermined that WY 1998 qualifies as an“unforeseeable and uncontrollable” event asdetermined by the Use Agreement.

In the memorandum, USBR requested the SL&D-MWA to work with the Technical Policy and ReviewTeam to partition the sources of the excessive seleniumloads discharged from February through June in order todetermine the amount of the load due to the “unforesee-able and uncontrollable” condition.

Joe McGahan, Drainage Coordinator for the GAF,worked with Sally Benson of Lawrence Berkeley Labora-tory to develop an analytical procedure for partitioningselenium loads. This effort was to identify those dischargesthat could be attributed to the “unforeseeable and uncon-trollable” conditions. An initial report dated September 16,1998 was submitted to the TPRT. A revised draft reportof this analysis was submitted to the TPRT on October28, 1998. The TPRT then prepared a separate reportdiscussing the partitioning of selenium loads and incentivefees. Based on these reports, on materials previouslypresented to the OC, coordination with the GAF, and on

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Chapter 1: Summary

248207 178

335

1,315

1,600 1,554

1,371

807

615

500

388348 348 389

533

866

1,066

799

666599 599

533

350

-

200

400

600

800

1,000

1,200

1,400

1,600

1,800

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Month

Se

len

ium

(p

ou

nd

s)

Discharge Load Value

February discharge includes 350 pounds released into Agatha Canal during storm event

Figure 3. Grassland Bypass Project Water Year 1998

Monthly Selenium Discharges into Mud Slough (Site B) Compared to Load Values

Year 1–2 Year 3 Year 4 Year 5

Oct 348 348 348 348Nov 348 348 348 348Dec 389 389 389 389Jan 533 506 479 453Feb 866 823 779 736

March 1,066 1,013 959 906April 799 759 719 679May 666 633 599 566June 599 569 539 509July 599 569 539 509Aug 533 506 480 453Sept 350 350 350 350

12-Month Total1 7,096 6,813 6,528 6,246Annual Load Targets 6,6602 6,3273 5,9944 5,6615

1. The 12-month total for any given year is somewhat higher than the annual load target for that yearbecause the monthly targets for the months of September, October, November, and Decemberhave been adjusted to allow for greater selenium discharge than would typically occur. Thisadjustment has been made to provide greater selenium management flexibility during monthswhen the assimilative capacity of the river is sufficient to sustain this greater load.

2. The annual 2nd year load target is based on the average annual loads discharged over a 9-yearhistorical period (1986–1994) which includes both wet- and dry-year data, as well as full and partialwater supply data. It is divided by month based on the average historical distribution of seleniumloads except where the Total Maximum Monthly Load (TMML) calculation (using a 1-in-5 monthviolation rate) allows for a greater monthly load.

3. The 3rd year annual load target is based on a 5% reduction of the average historical loads. The 5%reduction is applied equally across all months except where the TMML (using a 1-in-5 monthviolation rate) allows for greater monthly selenium loads.

4. The 4th year annual load target is based on a 10% reduction of the average historical loads. The10% is applied equally across all months except where the TMML (using a 1-in-5 month violationrate) allows for greater monthly selenium loads.

5. The 5th year annual load target is based on a 15% reduction from the average historical load. The15% is applied equally across all months, except where the TMML (using a 1-in-5 month violationrate) allows for greater monthly selenium loads.

Table 2. Selenium Load Targets (lbs)


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numerous discussions and meetings, the TPRT made thefollowing findings and recommendations.

Findings

As provided in the UA, the GAF submitted informationto the OC at the May 1998 public meeting supportingthe argument that “unforeseeable and uncontrollable”(UU) conditions existed during WY 1998. The TPRTfound that the available data indicated that “unforesee-able and uncontrollable” conditions existed from Febru-ary through June 1998.

The Grassland Area Farmers took reasonable stepsto control discharges during the UU conditions. Forexample, sumps were shut down during flooding eventsin an attempt to control the amount of dischargeexceeding the capacity of the Bypass.

The Grassland Area Farmers and the TPRTworked together, as well as separately, to develop a validmethodology for determining what portion of loads weredue to “unforeseeable and uncontrollable” conditions.These efforts highlighted the complexity of the hydro-logic system and helped to identify additional datacollection needs with regard to partitioning and under-standing the controllability of selenium loads.

The Technical and Policy Review Team agreed thatadditional data and analysis are needed before anypartitioning methodology can be applied. Therefore, theTPRT found that there is an insufficient technical basisto support the partitioning of selenium loads during the“unforeseeable and uncontrollable” events.

Recommendations

While the TPRT was unable to develop consensus for atechnical solution for determining selenium loads due tothe “unforeseeable and uncontrollable” conditions, theTPRT recognized that the OC must recommend toUSBR appropriate incentive fees for WY 1998. TheTPRT made the following recommendations to the OCfor consideration:

• Limit the fee waiver for the “unforeseeable anduncontrollable” event to the months of Febru-ary, March, April, May, and June for WY 1998.

• Waive incentive fees related to discharges ofselenium exceeding the annual load value forWY 1998.

• Assess incentives fees of $3,400 for dischargesin excess of the load values for July and Septem-

ber 1998 as per the UA and Consensus Letter(Table 1).

• The waiving of WY 1998 incentive fees asrecommended above should not be a precedentfor evaluating future selenium that exceedsannual load values.

• Work should continue on the development ofan approach for assessing heavy rainfall-runoffevents.

• Drainers and participating agencies shouldidentify and work to fill data gaps. For example,the TPRT would like to see additional informa-tion developed in the following areas: rainfallmonitoring, groundwater elevation monitoring,storm surface water run off (including Silver/Panoche Creek) and selenium concentrations atspecific on-farm sumps.

• Using the additional monitoring data, amethodology could be developed and improved.The objective of developing this methodology isnot only to assess unusual events but to assist inload management and meeting GBP goals.

• To accomplish collection of additional data, anew effort needs to be supported by resourcesoutside the current monitoring program.

1997 Incentive Fees Distributed

The Oversight Committee did not agree with the GAF’srequest for WY 1997 under the “unforeseeable anduncontrollable” provisions of the UA for heavy rainsduring January 1997. Consequently, excessive seleniumdischarges contributed to drainage incentive fees of$60,500. In accordance with Section II.H. of the UA, aDrainage Incentive Fee of $60,500 was calculated forWY 1997, and the SL&D-MWA deposited $60,500 inthe Drainage Incentive Fee Account. Section II.H.(6) ofthe UA states, in part:

The OC shall at least annually determine thedisposition of funds deposited in theDrainage Incentive Fee Account. Suchdetermination shall be made only afterconsultation with the Draining Parties andany other interested parties, and may bebased on recommendations from subcom-mittees established by the OC. These fundsare to be used for such programs or actions asthe OC determines will assist in meetingselenium load values stated in Appendix A tothe Consensus letter to the CVRWQCB

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Chapter 1: Summary

dated November 2, 1995 (Selenium LoadValue), and/or water quality objectives in theDrainage Area. In determining the disposi-tion of Account funds, the OC shall givespecial consideration to programs or actionsidentified in the San Joaquin Valley DrainageProgram Report.

The Technical and Policy Review Team solicited ideasfor use of the Incentive Fee from its members and frominterested parties including the GAF.

The Technical and Policy Review Team recom-mended that the $60,500 of 1997 Drainage IncentiveFees be transferred to the GAF for use in installingcontrols on subsurface drainage systems. Installation ofvalves on tile lines and/or other effective controls on tilesump discharges will assist the GAF, not only in manag-ing discharges during extreme weather events, but alsowill assist in meeting load values throughout the year. Atan estimated $2,000 to $3,000 cost per valve installation,the Drainage Incentive Fees would fund approximately20 to 30 installations. Use of these funds would supple-ment, and not replace, budgeted actions of the SL&D-MWA to accomplish drainage reduction targets. TheTPRT recommends that the GAF provide a report tothe OC with an accounting of the use of the DrainageIncentive Fee along with a description of the type,number, location, and effectiveness of tile sump controlmechanisms installed.

The Oversight Committee agreed with the TPRTand recommended the transfer of the $60,500 to theGAF. The OC also recommended the allocation of theincentive fees for the second year of $3,400 to be used forthe same purpose.

Monitoring ProgramThe Grassland Bypass Project monitoring plan contin-ued to serve the Project’s needs for the second year.Minor adjustments to the plan are envisioned during thethird year. Those changes will be documented andsubmitted for review during the summer of 1999. Theplan outlines the processes for collecting data to deter-mine if the terms and conditions of the GBP are beingmet. Flow, water quality, sediment, biota, toxicity, andbioaccumulation data are collected to assess the impactsof using the portion of the SLD to convey agriculturaldrainage water around the north and south Grasslandwetland areas (Table 3). The data gathered from thiseffort allow evaluation of the degree to which the

commitments of the UA, EA, Supplemental EA,FONSI, and consensus letter are being met.

Project OrganizationThe Grassland Bypass Project involves the coordinationand cooperation of several State and Federal agencieswhose authority, interests, or activities directly overlap inone or more aspects of the GBP. These agencies includeUSBR, USFWS, US Geological Survey, USEPA,CVRWQCB, California Department of Fish and Game,and the SL&D-MWA. The latter organization includeslocal drainage and water districts that use and operatethe Bypass.

Oversight Committee (OC)

The Oversight Committee is comprised of senior levelrepresentatives from USBR, USFWS, CDFG,CVRWQCB, and USEPA. The role of the OC is toevaluate all operations of the GBP, including monitoringdata, compliance with selenium load reduction goals, andother relevant information. The OC makes recommen-dations to the draining parties, USBR, and/or theCVRWQCB, as appropriate, regarding all aspects of theGBP. This includes modifications to the Project opera-tion, appropriate mitigative actions should significantimpacts be found to occur, extension of the UA after twoyears, and termination of the Agreement, if necessary.The OC also carries out functions required of it underthe UA which include determining the occurrence andextent of load exceedances, the amount of the drainageincentive fees that are payable, and actions or programsto be funded by the incentive fees.

The Grassland Bypass Project Oversight Commit-tee meets in a public forum quarterly, or as needed, toreview the status, progress, and monitoring results of theGBP. It considers findings and recommendations fromthe TPRT and other subcommittees. The OC alsoconsiders input and recommendations from the SL&D-MWA and other key stakeholders.

Technical and Policy Review Team(TPRT)

The Grassland Bypass Project Oversight Committeeformed the TPRT to serve as staff to the OC. The TPRTconsists of a representative from CVRWQCB, CDFG,USBR, USFWS, and USEPA, plus a member fromUSGS serving as an independent technical advisor. TheTPRT is responsible for obtaining and providing the


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necessary information, developing alternatives, andformulating recommendations to the OC for all issuesand decisions regarding the GBP. This includes produc-ing, or overseeing the production of, any analytical andinterpretive reports, and obtaining appropriate peer orscientific review as necessary. The TPRT is responsible forcoordinating, evaluating, and recommending associatedresearch and investigation needs as the GBP proceeds.The TPRT works closely with the DCRT, describedbelow, and, with approval of the OC, may designate andutilize additional subcommittees or task groups as neededto accomplish specific tasks or responsibilities.

Data Collection and ReportingTeam (DCRT)

The Data Collection and Reporting Team consists of theagency representatives and contractors responsible fordata collection and reporting. The DCRT is responsiblefor coordinating monitoring activities, identifying andresolving any issues involving data collection andreporting, and making recommendations for revision ofdata collection and reporting procedures as appropriate.The DCRT prepared the Monitoring Plan as well as the

associated Quality Assurance Project Plan (QAPP;Entrix, Inc., 1997). The DCRT meets monthly to reviewresults and coordinate monitoring activities.

Data Management

Each agency collecting data is responsible for its owninternal data quality and management procedures. Theseare detailed in the QAPP. In addition, each agencysubmits its data to the San Francisco Estuary Institute(SFEI), which, through a cooperative agreement withUSBR, serves as the overall data manager for this Project.

Reporting

The San Francisco Estuary Institute assembles, summa-rizes, and distributes monthly, quarterly and annualreports. Monthly reports and quarterly data reportsconsist of primary data from the 14 key monitoring sites,SLD (A, B), Mud Slough (C, D, E, I), Salt Slough (F),wetland channels ( J, K, L, M), and the San JoaquinRiver (G, H, N). The monthly report presents datacollected during that particular month, including thecalculated selenium load discharged at Site B, the

Table 3. Monitoring Sites, Parameters, and Frequencies

Site Water Sediment Biota Toxicity

Flow Temp pH EC TSS Se B Bed Se Se Tumors In- In- Bio-

Situ lab accumulation

San Luis Drain A C W W W W W W QB C C W C W D W Q Q M M

1–2 A10–11 A14–15 A17–18 A

Mud Slough C W W W W W Q Q Q M MD C C W C W W Q Q Q Q M ME BM BM BM BM BM Q Q QI A A A A A A A A

Salt Slough F C C W C W W Q Q Q Q M M

Wetland ChannelsJ—Camp 13 Ditch W W W W WK—Agatha Canal W W W W WL—San Luis Canal W W W W WM—Santa Fe Canal W W W W W

San Joaquin RiverG—Fremont Ford W W W W W Q QH—Hills Ferry W W W W W Q QN—Crows Landing C C W C D W

KEYC = continuous BW = biweekly (every 2 weeks) Q = quarterlyD = daily M = monthly A = annuallyW = weekly BM = bimonthly (every 2 months)

11

Chapter 1: Summary

terminus of the SLD. Quarterly data reports consist ofall available data from all sites during a 3-month period(SFEI, 1997–1998a). SFEI also prepares narrative andgraphical summaries of the most recent Project data on aquarterly basis (SFEI, 1997–1998b). The focus of SFEIis to report data and information from all sampling sitesin a timely manner. All reports are distributed to theparticipating parties and are available upon request.

In addition to the reports, a website for the GBPprovides current data for many of the sites. Also availableon the website are pre-Project data, related scientificstudies, photographs of many of the sites, and other relatedtopics. Visit the GBP website at http://www.mp.usbr.gov/mp150/grassland/index.html.

ReferencesEntrix, Inc. 1997. Quality Assurance Project Plan for the

Compliance Monitoring Program for Use andOperation of the Grassland Bypass Project (FinalDraft). Prepared for the U.S. Bureau of Reclama-tion, Sacramento, CA. June 20, 1997.

Grassland Area Farmers, et al. 1997. Grassland BypassChannel Operations During Two Major StormEvents in January, 1997. A Report to the CaliforniaRegional Water Quality Control Board for theCentral Valley Region. Los Banos, CA. April 1997.

San Francisco Estuary Institute. 1996–1998. GrasslandBypass Project Monthly Data Report. October1996 through September 1998 (24 reports).Richmond, CA.

San Francisco Estuary Institute. 1997–1998a. GrasslandBypass Project Quarterly Data Report. October

1996 through September 1998 (8 reports).Richmond, CA.

San Francisco Estuary Institute. 1997–1998b. GrasslandBypass Project Quarterly Narrative and GraphicalSummary. October 1996 through September 1998(6 reports). Richmond, CA. August 1998.

U.S. Bureau of Reclamation. 1995. Finding of NoSignificant Impact and Supplemental Environ-mental Assessment. Grassland Bypass ChannelProject. Interim Use of a Portion of the San LuisDrain for Conveyance of Drainage Water ThroughGrassland Water District and Adjacent GrasslandAreas. November 1995. U.S. Bureau of Reclama-tion, Mid-Pacific Region, Sacramento, CA.

U.S. Bureau of Reclamation. 1997. Impact of the January1997 Flood Event on the Grassland BypassChannel Project. U.S. Bureau of Reclamation, Mid-Pacific Region, Sacramento, CA. September 1997.

U.S. Bureau of Reclamation. 1997. Grassland BypassChannel Project Incentive Fee Assessments. Letterto Dan Nelson, Manager, San Luis & Delta-Mendota Water Authority from Roger Patterson,Regional Director, Mid-Pacific Region, U.S.Bureau of Reclamation. December 2, 1997.

U.S. Bureau of Reclamation and the San Luis & Delta-Mendota Water Authority. 1995. Agreement forUse of the San Luis Drain. Agreement No. 6-07-20-w1319, November 3, 1995.

U.S. Bureau of Reclamation et al. 1996. ComplianceMonitoring Program for Use and Operation of theGrassland Bypass Project, September 1996. U.S.Bureau of Reclamation, Mid-Pacific Region,Sacramento, CA.


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13

Chapter 2: Drainage Control Activities

Chapter 2

Drainage ControlActivities by

Grassland AreaFarmers

Joseph C. McGahanDrainage Coordinator


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A short-term drainage management plan (STDMP) wasdeveloped for the Grassland Drainage Area (GDA) in1997. A copy was submitted to the Central ValleyRegional Water Quality Control Board (CVRWQCB)as part of the Report of Waste Discharge for the Grass-land Bypass Project (GBP) on August 25, 1997. WasteDischarge Requirements (WDRs) were issued for theGBP on July 24, 1998. The WDRs require that theSTDMP be updated by January 1, 1999. The revisedplan is required to 1) discuss projected impacts of themanagement plan on discharges of boron, molybdenum,and salt from the GBP and 2) evaluate potential controland treatment methods and identify any additionaltechnically and economically feasible control measuresthat can be implemented before October 2001 todecrease discharges of boron, molybdenum, or salt.

The short-term drainage management plan focusesprimarily on activities to reduce discharges of selenium asrequired by the selenium control program, whichincludes a 5% reduction in water year (WY) 1999. A listof the components of the STDMP is included in Table 1on page 21. Most of the regional activities relate todevelopment of the drainage organization, educationalfunctions, monitoring and testing, and program develop-

ment. One new regional activity is the EconomicIncentives Program, developed by our consultant, SusanAustin, made available through a grant from the StateWater Resources Control Board and the U.S. Environ-mental Protection Agency. Actual selenium controlmeasures, including those developed through theRegional Active Land Management and EconomicIncentives Program are carried out at the district andfarm-levels. New district and farm-level activities includetreatment projects and drain water displacement projects.A discussion of actions and developments in each of theSTDMP components follows Table 1.

The contribution to regional reduction of drainagedischarges from each of the individual plan componentsis difficult to ascertain. On a district level, the PanocheDrainage District (PDD) has developed preliminaryinformation estimating the contribution in selenium loadreduction from various plan components (see Figures 1and 2). Figure 1 shows the estimated reductions atpresent and Figure 2 estimates reductions by September2001. As part of the STDMP, PDD will be evaluatingthe accuracy of these estimates and the regional entity, incooperation with the other districts will consider whetheror not those districts, will be able to produce similar data.

Figure 1. Panoche Drainage District

Estimated Current Component Reductions

River Outlet

Irrigation Improvements

Selenium Removal Projects

Recirculation System

Salt Tolerant Crops

Displacing

15


On the other hand, the area-wide general progressin control of discharged selenium is demonstrable. Figure3 shows the discharge from the drainage area for WYs1995 through 1998. WY 1998 has been determined bythe Oversight Committee to be an “unforeseeable anduncontrollable year” as defined in the Use Agreement forthe Grassland Bypass Project. This is mainly due to thefact that rainfall was the highest ever recorded in the area.This extremely high rainfall caused high drainage flowsboth from tile systems and from Panoche/Silver Creek.The estimated contribution from Panoche/Silver Creek isshown. It is evident from Figure 3, however, that drainagedischarges measured in pounds of selenium were reducedby 24% in WY 1998 compared to WY 1995, which was asimilar year of high rainfall. This is selenium load thatwas not discharged to the wetlands and the San JoaquinRiver System. In addition, Figure 4 shows the dischargefrom tile drainage systems in WYs 1997 and 1998 withinthe GDA compared to the discharge from the GDA. Itcan be seen that 34% of the discharge from tile sumpswas prevented from discharging from the area both inWY 1997 and WY 1998. Figure 5 shows the pounds ofselenium not discharged to the San Joaquin River inWYs 1997 and 1998 due to subsurface drain watermanagement activities within the GDA.

Shown on Figures 6, 7, and 8 are conditions thatoccurred during the flooding in WY 1998.

Comparison of February 1999 with February 1998(Figure 9) indicate that when conditions allow farmers tocontrol the drainage discharge, targets can be met.Irrigation in February 1999 was 14,000 acre-feet (AF)compared to 1,600 AF in February 1998. Rainfall inFebruary 1999 was 1 inch (8,000 AF over the drainagearea) and in February 1998 was 4.4 inches (36,000 AF).Drainage loads in February 1999 are estimated to be 615pounds or 27% under the monthly target. In February1998 the load was 1,315 pounds or 52% over themonthly target. The 1998 loads appear from these datato be much more rainfall driven than irrigation driven.

Water Quality ObjectivesThe Grassland Bypass is being operated mainly forcontrol of selenium. The compliance date is October 1,2010 for both Mud Slough and the San Joaquin River.The control method currently is based on load limita-tions as outlined in the Use Agreement for the GBP andthe WDRs. The STDMP is based on actions to meet theselenium load limitations.

Figure 2. Panoche Drainage District

Estimated Component Reductions by September, 2001

Displacing

Salt Tolerant Crops

Recirculation System

Selenium Removal Projects

Irrigation Improvements

River Outlet


16

0

2000

4000

6000

8000

10000

12000

14000

WY 1995 WY 1996 WY 1997 WY 1998Water Year

Sele

niu

m (

lbs)

Drainage Area DischargePanoche/Silver Creek Discharge

537 lbs Pan./Silver Ck.3

24%14%

487 lbsPan./Silver Ck.316 lbs

Pan./Silver Ck.3

11,8751

10,0341

7,0972

9,1182

Source of Data:1 RWQCB2 Monitoring Program3 Estimated by Grassland Area Farmers

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Se

len

ium

(lb

s)

District DischargePanoche/Silver Creek Discharge

Drainage AreaDischarge

Tile SumpDischarge

Drainage AreaDischarge

Tile SumpDischarge

WY 1997 WY 1998

Panoche/Silver3

Creek Discharge:16 lbs

34% Reduction due to Drainage

Management Activities

Panoche/Silver Creek3

Discharge:487 lbs

34% Reduction due to Drainage

Management Activities

Note: Tile Sump Discharge reflects reduction due to control measures other than displacement.

7,0971

10,7602

9,1181

12,9962

Source of Data:1 RWQCB2 Monitoring Program3 Estimated by Grassland Area Farmers

Figure 3. Annual Selenium Load from Drainage Area

Figure 4. Grassland Drainage Area Selenium Discharge

17


3,679

4,365

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

Water Year

Se

len

ium

(lb

s)

WY 1997 WY 1998

Figure 5. Selenium Load Not Discharged to San Joaquin River

Figure 6. Panoche/Silver Creek at I-5 at 8:00 a.m.

2/3/98—7,000 cfs.


18

Figure 7. Firebaugh Canal Water District 3rd Lift Canal

Shaw Avenue in Foreground February 10, 1998

Figure 8. Sump Overflowing Because of Being Shut Off

February 16, 1998

19


01998 1999

Acre

Feet

February Irrigation

16,000

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Inch

es

1998 1999

February Rainfall

0

200

400

600

800

1,000

1,200

1,400

Po

un

ds

1998 1999

February Selenium Load

Figure 9. Comparison of February 1998 and 1999

Rainfall, Irrigation, and Selenium Load

As anticipated, selenium objectives have continuedto be exceeded in Mud Slough downstream of thedischarge from the San Luis Drain (SLD). It is notanticipated that selenium objectives for Mud Slough canbe met after the compliance period so long as dischargesinto the Slough continue, unless alternative compliancerequirements are fashioned or unless treatment becomesavailable. In Salt Slough, selenium objectives wereexceeded in WY 1996, but by WY 1997, the first year ofoperation of the Grassland Bypass, selenium objectiveswere met for Salt Slough, which was a major purpose ofthe GBP. Similarly, in WY 1998 water quality objectivesfor selenium were met in Salt Slough, except for a periodof time in February 1998 when uncontrollable floodflows were discharged. The 5 ppb monthly meanselenium objectives were exceeded in the San JoaquinRiver at Crows Landing in 2 out of 12 months in bothWYs 1996 and 1997. The 5 ppb 4-day running averageselenium objective was exceeded more frequently. Themonthly mean selenium objectives were achieved atCrows Landing in all months of WY 1998. This wasmainly due to the high river flows.

Prior to implementation of the GBP, subsurfacedrainage flows were contained in the wetland channels.For example, in WY 1996 the mean selenium concentra-tion at Camp 13 Slough was 59.5 ppb. In WY 1997, thefirst year of operation of the GBP, the mean seleniumconcentration at Camp 13 Slough was 2.6 ppb. Althoughnot meeting the wetland selenium monthly meanobjective of 2 ppb in all months, 99% of the goal of theGBP (to remove selenium from wetland channels andmeet the 2 ppb objective) was achieved in the first year.In WY 1998 selenium concentrations were similar toWY 1997. The Grassland Area Farmers have takenactions to prevent discharges from the GDA to thewetland channels and are working with the CVRWQCBto identify and control discharges to wetland channelsfrom areas outside the GDA.

Exceedances of water quality objectives haveoccurred for boron and molybdenum. In WY 1996, theyear prior to operation of the Grassland Bypass, boronobjectives were exceeded in Mud Slough downstream ofSLD (which was not discharging) and in Salt Slough.Boron objectives were also exceeded in the San JoaquinRiver at Crows Landing for both WYs 1996 and 1997.In WY 1997, the first year of operation of the GrasslandBypass, boron concentrations were exceeded in MudSlough upstream of the discharge from SLD and in MudSlough downstream of the discharge. The boron objec-tive in Salt Slough was met in WY 1997. This fact issignificant in that one major purpose of the GBP was toimprove conditions in Salt Slough.


20

Molybdenum objectives were not exceeded in thesloughs in WY 1996 but were exceeded in Mud Sloughdownstream of the discharge from SLD in WY 1997and, although the data were not available, objectives werelikely exceeded in WY 1998 as well.

Impact of the Project onDischarges of Boron,Molybdenum, and SaltsThe sources of boron, molybdenum, and salt are notwell understood. Boron, molybdenum, and salt from theGDA will be reduced as drainage flows are reduced forselenium control. However, management of sumps toreduce selenium discharges does not necessarily result inthe same reduction of discharges of boron, molybde-num, or salt. This is because the concentrations ofboron, molybdenum, and salt in individual sumps thatare being managed for selenium are not necessarilyproportionally as great a percentage of overall dischargeas selenium.

Currently in the STDMP boron and molybdenumviolations will likely continue to occur but concentrationswill reduce as drainage flows reduce. Reduced drainageflows result in less boron, molybdenum, and salt beingdischarged than without the GBP.

Figure 10 shows salt discharges for WYs 1995through 1998. The salt load discharged from Mud andSalt sloughs decreased in WY 1997 compared toprevious years and the discharge from the Drainage Areaalso decreased. In WY 1998 the salt load from Mud andSalt sloughs increased from previous years. This is likelydue to the extremely wet conditions. In WY 1998 thecombined flow from Mud and Salt sloughs was 45%greater than in WY 1995 while the flow from theDrainage Area was 15% less. Mud and Salt sloughs drainthe entire Grassland Watershed including high flows inWY 1998 from Los Banos Creek. In WY 1998 the saltload from the Drainage Area was approximately equal toWY 1995 and 11% less than WY 1995, mainly as asecondary benefit to the selenium control measures takenin WY 1998.

0

To

ns S

alt

700,000

600,000

500,000

400,000

300,000

200,000

100,000

WY 1995 WY 1996 WY 1997 WY 1998*

Water Year

* Preliminary Data—Includes Panoche/Silver Creek Discharge

Salt and Mud sloughs Drain Area

Figure 10. Grassland Basin Salt Load

21


Potential Measures toDecrease Discharges ofBoron, Molybdenum,and SaltThe Grassland Area Farmers are continually evaluatingmeasures that will result in the reduction of boron,molybdenum, and salt. All the selenium control measurescreate incidental reductions of these constituents. TheGrassland Area Farmers will analyze available data onthe impact of the control measures on boron, molybde-num, and salt during this next year.

All of the STDMP components affect drainagebefore it comes out of the tile drainage systems, exceptfor the displacement components which include recy-cling, displacement such as sprinkling roadways and useon alternate crop areas, and the active land managementprogram which uses drainage water on salt tolerant crops.The amounts of discharge shown in Figure 3 reflectthese components including displacement. The displace-ment component is reflected in the reduction in Figure 4.

The water from the tile sumps amounted to0.62 AF/drained acre in WY 1998, compared to0.52 AF/drained acre in WY 1997, and compared to

0.55 AF/drained acre average during the WY 1986–1994period. Of course, WY 1998 was an excessive year forrainfall and WY 1997 was an above normal water supplyand rainfall year. In addition WYs 1986-1994 included aperiod of prolonged drought. One of the main compo-nents of the STDMP is to reduce the water dischargedfrom tile sumps.

Total drainage discharged from the drainage areahas decreased from an average of 1.07 AF/drained acrein WY 1986–1994 to 0.52 AF/drained acre in WY 1997and 0.64 AF/drained acre in WY 1998. This value inWY 1998 includes the surface flows generated from localflood runoff and westside stream flows. This indicates asignificant reduction mainly in the tailwater componentof the drainage discharge from the drainage area.

Components of ShortTerm DrainageManagement Plan—UpdateRegional Components

Regional Drainage Entity (Activity Agreement)—The Grassland Area Farmers activity has approved abudget of $884,000 for the fiscal year that commencedMarch 1, 1998. The Steering Committee continues tomeet monthly with active participation not only bymembers, but by representatives of the U.S. Bureau ofReclamation, California Department of Fish and Game,and Central Valley Regional Water Quality ControlBoard. The Steering Committee adopted and allmembers approved a Rule Enforcing Selenium LoadTargets and Tailwater Restrictions as Amended March27, 1998 and also a Rule Establishing Tradable LoadsProgram for WY 1998. This latter rule led to one formalload trade during 1998 and has been adopted on aninterim basis for 1999. The Steering Committee iscurrently working on combining the two rules for 1999and expanding the Tradable Loads Program (seediscussion below).

Regional Drainage Coordinator—Joseph McGahanof Summers Engineering, Inc. currently serves asRegional Drainage Coordinator. The Regional DrainageCoordinator continues to compile and circulate allregional data and acts as executive officer to the SteeringCommittee. He prepared the Report of Waste Dischargeand all supplemental information leading to issuance ofWaste Discharge Requirements. He has appeared before

Table 1. Components of Short Term Drainage

Management Plan

Regional Components

• Regional Drainage Entity (Activity Agreement)• Regional Drainage Coordinator• Irrigation and Drainage Workshops• Regional Newsletter• Regional Monitoring Program• Toxicity Testing• Active Land Management Program• Economic Incentives Program (new)

District-Level Components

• Low interest water conservation equipment loans• Tiered water pricing• Sprinkler pre-irrigations• Tailwater recirculation• Sump management (measurement, level

manipulation, and cycling)• Drain water recycling• Drain water displacement projects (new)• Drain water treatment (new)• Limited water transfers (new)

Farm-Level Components

• Improved irrigation methods and application •Tailwater return ponds

• On-farm recycling


22

the Oversight Committee established by the UseAgreement, appeared before the CVRWQCB, providedtestimony to the State Water Resources Control Boardin Phase 5 of the Bay-Delta Hearings, and representedthe drainers on the multi-agency Data Collection andReporting Team, part of the Grassland Bypass Project(GBP) monitoring effort.

Irrigation and Drainage Workshops—A total of 22workshops have been held to date, for landowners, waterusers, and irrigation supervisors in each of the memberdistricts.

Regional Newsletter—The regional newsletter keepsinterested parties informed about drainage issues, newirrigation efficiency techniques, upcoming workshops, orissues demanding on-farm responses.

Regional Monitoring Program—Both the regionalentity and various districts have continued to upgrademonitoring capabilities with installation of real timemonitoring equipment. Samples continue to be taken onthe schedule required by the Finding of No SignificantImpact (FONSI) for the Use Agreement.

Toxicity Testing—The Grassland Area Farmers’toxicity testing program has continued with BlockEnvironmental performing the analysis. The onlystatistically significant trend that has developed isreduced reproduction of selenastrum alga in the San LuisDrain (SLD) itself. The testing has shown effects in areasoutside of the drainage impacted waters, such as Site Cin Mud Slough upstream of SLD discharge. Theseimpacts are being evaluated separately from the GBP.

Active Land Management Program—NEW—Approximately 3,000 acres within the Grassland Drain-age Area are included in this program, which has beenfunded by USBR through the regional entity. It is acombination of demonstration projects using recycleddrainage water on salt tolerant crops and measuring theimpacts on soils and crop production. Drainage flows onselected parcels are monitored to determine response toirrigation and other drainage related events. Thisprogram is intended to continue as a short-term compo-nent but may be expanded. It is one displacementcomponent which reduces the discharge from the GDA.

Economic Incentives Program—NEW—TheSteering Committee, with assistance from a consultanthired under a State Water Resources Control Board

Grant, is continuing to develop this program. It includestiered water pricing and the tradable loads program forselenium. Current activities include developing a policythat calls for fees to be paid by individual activityagreement members that go over their load allocationand rebates paid to those members that go under theirallocation. In addition any incentive fee paid by the areaas a whole would be paid only by those members thatexceed their allocation. The program also includes atrading program to allow trades between members toavoid individual exceedances. Districts less able tomanage loads will be able to acquire load allocationsfrom those with more capacity. This component will be amajor part of the short-term plan.

District-Level Components

Low Interest Water Conservation Equipment

Loans—Previous experience with the State RevolvingFund Program has shown that drainage and productionbenefits can be achieved on certain soils with improvedirrigation systems such as sprinkler and drip irrigation.This will continue to be a component of the short termplan in conjunction with tiered water pricing and thepreirrigation management program. The Grassland AreaFarmers have funded $7,700,000 in such improvementsthrough these programs to date.

Tiered Water Pricing—All district participants in theGBP have implemented tiered water pricing programs.As part of the Economic Incentives Program the tieredwater pricing program is to be evaluated in terms of itseffectiveness in reducing drainage. The purpose of tieredwater pricing programs is to encourage the efficient useof water so as to reduce deep percolation. The pricingprograms apply to both lands upslope and lands thatoverly tile drainage systems. The effectiveness of thisprogram is difficult to measure. All districts remaincommitted to these programs for drainage reduction andwater conservation.

Sprinkler Pre-irrigation—The recycling displacementsystems are more effective in the high irrigation demandsummer period. Irrigation water can be mixed withsubsurface drainage water and delivered to fields atreasonable salinity levels. This opportunity does not existto the same degree during the preirrigation period. Thepurpose of the tiered water pricing policies and puttingimproved irrigation systems in place are to reduce thesubsurface drainage produced during this period. This isalso the period when the vertical permeability is greatest

23


as part of the cultural practice is to deep rip and break upbound clay soils in preparation for preirrigation and theplanting season. An important component of this efforthas been the convening of workshops to educate ranchmanagers and field irrigation personnel of the need toapply water carefully so as not to produce excessivesubsurface drainage. This will continue to be a maincomponent of the short term plan with an increasedemphasis on preirrigation water management. Districtsare holding workshops this winter.

Tailwater Recirculation—All members have adoptedrequirements that tailwater be kept on farm, in accor-dance with the Rule adopted by the Steering Committeeof the Grassland Area Farmers. District wide and/or on-farm systems have been implemented in all areas withinthe GDA.

Sump Management (Measurement, Level

Manipulation, and Cycling)—All pumped sumpswithin the GDA are currently metered and measured bythe overlying district. These data are used regionally andby each district in applying management techniques.Level manipulation (adjusting the level of the probes inthe sump which control the pump operation and also thewater level in the field) and cycling (turning pumps off

for a period of time) have not yielded encouraging resultswithin the GDA. It has been shown that when drainagesystems are shut off, water at the sump end of thedrainage system surfaces and runs out the sump (seeFigure 8). In addition water stored within the drainageprofile is discharged when the systems are turned backon and there is no overall reduction in subsurfacedrainage volume. During the flood discharges to thewetlands in February 1998 most pumped subsurfacedrainage systems were shut off. Drainage dischargesremained excessive the remainder of the year largely dueto the removal of this stored water. Although cyclingcould have some benefit in a timed release program,there is not enough storage in the soil profile to realizesignificant benefit without external ponded storage.

Drain Water Recycling—Recycling will be the majorcomponent of the STDMP through September 2001.The best example comes from Panoche DrainageDistrict. The recirculation system that was constructed inWY 1998 has the ability to recycle the drainage waterfrom the 15 sumps of 61 sumps within the district thathave the highest selenium concentrations, which allowsfor recycling 75% of the total selenium load production inthe District. The Panoche recirculation system is shownin Figure 11. The system pumps subsurface drainage

Figure 11. Panoche Drainage District Recirculation System

Completed May 1998


24

which is high in salinity and boron and mixes it with theirrigation water supply from the San Luis Canal (Califor-nia Aquaduct). The operation is closely monitored tolimit the salinity and boron levels in the mixed water.Broadview, Firebaugh, Pacheco, and Charleston have inplace, or are installing, recycling systems. $8,300,000 hasbeen spent by districts implementing recycling systems.

Drain Water Displacement Projects—NEW—Inaddition to recycling, displacement projects includesprinkling roadways for dust control, use on alternatecrops, and use of drainage water on salt tolerant crops.These projects will continue to be evaluated this nextyear to establish their efficacy in drainage reduction.

Treatment—NEW—Districts continue to exploredrainage treatment techniques. Panoche DrainageDistrict is hosting a treatment project funded throughthe Calfed Bay-Delta program. A full scale sumptreatment system is being installed which may helpmanage molybdenum, boron, and salt, as well as sele-nium. Broadview Water District is investigating a flowthrough wetland which has shown promise in the TulareLake Area. Firebaugh Canal Water District is investigat-ing selenium and salt removal through a membranetreatment process. All these processes are more likely tobe applicable to the long-term solution but may beavailable in the short-term.

Limited Water Transfers—NEW—Two entitieswithin the Grassland Drainage Area, Widren WaterDistrict and Mercy Springs Water District (a portion ofwhich is within Panoche Drainage District), haveproposed assignment of some or all of their CentralValley Project (CVP) contractual water supplies. The

areas would remain under cultivation for salt-tolerantcrops, utilizing groundwater and drain water to supple-ment any remaining contractual supplies. Goals includereduction in drainage from those areas and opportunityfor re-use of drainage from nearby areas. Such arrange-ments on a limited number of acres provide one aspect ofalternative land management available in the STDMP.These limited changes in CVP water supplies are still inprocess and may not be effective in WY 1999.

Farm-Level Components

Improved Irrigation Methods and Application—Application of improved irrigation systems and techniquesultimately rests at the farm level. The districts are active inhelping provide equipment and information to the farmlevel operators. This information includes irrigationtechniques to reduce drainage and information regardingthe need for reduction including the incentive fee pay-ments required if the GDA exceeds its allocation. Thisinformation process will continue during the next year.

Tailwater Return Ponds—Many farm operators haveinstalled on-farm return systems to prevent discharge oftailwater. Although tailwater generally does not containselenium, it does contain sediment. On-farm manage-ment of tailwater leads to more efficient irrigation, whichreduces subsurface drainage discharges.

On-farm Recycling—Some on-farm operators utilizeon-farm recycling in addition to the District levelsystems. Either the on-farm systems are not connected tothe District wide system or it is beneficial for theoperator to recycle on-farm. These systems will continueto be operated this next year.

25

Chapter 3: Flow and Salinity Monitoring

Chapter 3

Grassland BypassProject Flow and

Salinity Monitoring

Michael C.S. Eacock, U.S. Bureau of ReclamationNigel W.T. Quinn, Lawrence Berkeley National Laboratory


26

0.00

0.25

0.50

0.75

1.00

1.25

1.50

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97

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/97

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/97

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/97

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97

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/97

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/97

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/97

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/97

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/97

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/97

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8

Pre

cip

ita

tio

n (

inch

es)

0

75

150

225

300

375

450

525

600

Data Provided by Summers Engineering

Daily D

isch

arg

e (

acre

feet)

Panoche CIMIS Precipitation Discharge from GBP (af) Target Flows (af)

Figure 1. Grassland Bypass Project 1998 Water Year Rainfall and Discharge

SummaryFlow and salinity monitoring activities were carried outas specified in the Compliance Monitoring Program for theGrassland Bypass Project (GBP; USBR et al., 1996). Flowand electrical conductivity (EC) readings were taken at15 minute intervals and averaged to obtain daily meanvalues from the San Luis Drain (SLD), Salt Slough,Mud Slough, and the San Joaquin River at CrowsLanding. Lawrence Berkeley National Laboratory(LBNL) and the U.S. Geological Survey (USGS)performed site maintenance, sensor calibration, and dataprocessing for each month. The San Francisco EstuaryInstitute (SFEI) compiled this information in monthlyand quarterly reports.

During the 1998 Water Year (WY; October 1,1997–September 30, 1998), unusually high springrainfall and regional flooding influenced flow measure-ment activities. Figure 1 shows the pattern of precipita-tion and resulting discharge during the WY 1998. TheGrassland Bypass conveyed primarily floodwater fromFebruary through June 1998. Monitoring sites in Mudand Salt sloughs experienced backwater conditions as aresult of high stage in the San Joaquin River betweenFebruary and late July. This condition necessitated

frequent site visits to collect accurate flow measurementsand to produce valid stream rating curves.

Despite the adverse conditions, the data record forthe WY 1998 is complete with less than 3 days ofdowntime for which interpolated data had to be used.Flow and EC sensors required minimal adjustment tomaintain calibration during the monitoring period.Tables 1 and 2 summarize monthly flow, salinity, andselenium data collected during the WY 1998.

The current and historic data can be found on theGBP website at:

http://www.mp.usbr.gov/mp150/grassland/Resources/Data/dhome.html

Purpose of FlowMonitoringFlow is an important parameter in the measurement ofselenium, boron, and salt loads in agricultural drain waterleaving the Grassland basin. Such flows can fluctuatewidely and are especially susceptible to winter rainstorms.

The Grassland Basin Project Compliance Moni-toring Program (USBR, 1996) specifies that flows mustbe measured for the computation of discharge, to

27

Chapter 3: F

low and Salinity M

onitoring

Oct-97 Nov-97 Dec-97 Jan-98 Feb-98 Mar-98 Apr-98 May-98 Jun-98 Jul-98 Aug-98 Sep-98Annual Totals

Station A—San Luis Drain near Dos Palos, CAFlow LBNL acre-feet 1,335 994 1,070 1,230 6,832 7,075 5,444 4,713 3,629 4,537 3,849 2,838 43,546 EC RB µS/cm 5,095 4,668 5,322 5,463 3,198 4,683 5,042 5,110 5,168 4,424 4,285 3,932 TDS mg/L 3,261 2,988 3,406 3,496 2,047 2,997 3,227 3,270 3,308 2,831 2,742 2,516 Salt Load tons 5,920 4,039 4,957 5,849 19,017 28,838 23,891 20,962 16,324 17,470 14,355 9,713 171,336 Selenium RB (w) ppb 63.6 65.8 70.7 86.8 45.3 76.7 108.9 97.6 82.8 48.9 46.7 48.7Se Load lbs 231 178 206 290 842 1,475 1,613 1,251 818 604 489 376 8,372

Station B—San Luis Drain TerminusFlow LBNL acre-feet 1,776 1,568 1,370 1,458 7,184 7,069 5,434 4,897 3,640 4,565 3,875 3,071 45,907 EC RB µS/cm 4,936 4,715 4,610 5,088 3,679 4,993 5,700 5,633 5,218 4,424 4,322 4,034 TDS mg/L 3,159 3,018 2,950 3,256 2,355 3,196 3,648 3,605 3,340 2,831 2,766 2,582 Salt Load tons 7,630 6,435 5,497 6,457 23,005 30,721 26,960 24,010 16,532 17,578 14,577 10,783 190,185 Selenium RB (d) ppb 52 49 49 85 53 83 105 104 82 50 47 43Se Load RB lbs 248 207 178 335 965 1,600 1,554 1,371 807 615 500 388 8,768

Conversion factors Site A Site BAF-mg/L => tons 0.00136 Specific Conductance => TDS 0.64 0.64AF-ppb => lbs 0.00272

Data Sources:Flow: LBNL—Lawrence Berkeley Nat. Lab.Salinity and Selenium: Cal. Regional Water Quality Control Board (RB)

Flow calculated from continuous measurements.Salt load calculated from mean daily measurementsd—Selenium load calculated from daily composites of 6 samplesw—Selenium load calculated from weekly composite of 7 daily samples

Table 1. Summary of Monthly Salt and Selenium Loads

Grassland B

ypass Project A

nnual Report

28

Oct-97 Nov-97 Dec-97 Jan-98 Feb-98 Mar-98 Apr-98 May-98 Jun-98 Jul-98 Aug-98 Sep-98Annual Totals

Station D - Mud Slough near Gustine, CAFlow USGS acre-feet 8,061 9,975 12,000 20,309 53,030 34,594 12,450 7,553 5,814 6,984 5,581 6,262 182,613 EC RB (w) µS/cm 2,017 2,033 2,080 2,041 1,264 2,393 3,716 4,295 3,205 3,196 3,368 3,060 TDS mg/L 1,391 1,403 1,435 1,408 872 1,651 2,564 2,964 2,211 2,205 2,324 2,111 Salt Load tons 15,254 19,030 23,420 38,901 62,884 77,676 43,414 30,442 17,486 20,946 17,636 17,981 385,071 Selenium RB (w) ppb 12.1 7.9 6.9 8.6 7.2 20.5 52.2 67.3 43.0 31.6 33.1 29.1Se Load lbs 266 215 224 475 1,039 1,927 1,769 1,383 679 600 502 496 9,574

Station F - Salt Slough at Hwy 165 near Stevinson, CAFlow USGS acre-feet 7,638 9,213 7,896 8,569 34,959 29,272 18,290 16,768 16,675 17,700 18,163 10,750 195,893 EC RB (w) µS/cm 1,262 1,561 2,183 2,178 1,775 1,705 1,846 1,137 835 675 795 914 TDS mg/L 858 1,062 1,484 1,481 1,207 1,159 1,255 773 567 459 541 622 Salt Load tons 8,916 13,302 15,937 17,260 57,394 46,149 31,224 17,632 12,869 11,049 13,358 9,087 254,176 Selenium RB (w) ppb 1.0 1.0 1.2 1.3 4.0 1.9 1.2 0.9 0.6 0.7 1.1 0.8Se Load lbs 20 25 26 30 383 153 60 39 26 35 52 24 872

Station N - San Joaquin River near Crows Landing, CAFlow USGS acre-feet 39,860 44,690 53,260 139,600 1,001,000 623,100 832,100 743,600 707,300 502,700 108,100 109,600 4,904,910 EC RB (w) µS/cm 1,039 1,209 1,383 1,078 404 546 332 232 166 232 674 497 TDS mg/L 644 750 857 668 250 339 206 144 103 144 418 308 Salt Load tons 34,921 45,558 62,109 126,892 340,993 286,867 232,940 145,339 98,882 98,255 61,389 45,930 1,580,077 Selenium RB (w) ppb 2.5 2.3 1.8 1.7 0.9 1.7 1.1 1.1 0.8 0.9 2.4 1.7Se Load lbs 273 280 264 646 2,519 2,924 2,444 2,275 1,475 1,196 698 507 15,501

Conversion factors Site D Site F Site NAF-mg/L => tons 0.0014 Specific Conductance => TDS 0.69 0.68 0.62AF-ppb => lbs 0.0027

Data Sources: Flow: USGSSalinity and Selenium: CVRWQCB

Flow calculated from continuous measurements.Salt load calculated from mean weekly measurementsw—Selenium load calculated from weekly composite of 7 daily samples

Table 2. Summary of Monthly Salt and Selenium Loads

29


Grassland Bypass Project Site A

Location San Luis Drain Check 17, nearDos Palos California (USGS11262890)

Responsibility San Luis & Delta-Mendota WaterAuthority, Lawrence BerkeleyNational Laboratory

Parameters Stage, salinity, temperature

Equipment Stevens Recorder, Keller pressuretransducer, staff gauge, weirstick, Campbell 247 electricalconductivity/temperature probe,Campbell CR 10 datalogger

establish seasonal flow patterns, and to determine theinfluence of the GBP discharge on the hydrology of MudSlough and the San Joaquin River. According to theInterim Use Permit (USBR and SL&D-MWA, 1995)discharge flow from the San Luis Drain into MudSlough may not exceed 150 cubic feet per second.

In the GBP, various methods are used to calculateflow rate according to the location and purpose of eachmonitoring site. Each flow monitoring method waschosen to obtain the best possible data with the greatestreliability under constraints of the GBP monitoringbudget. Redundancy was employed at the most criticalsites to reduce the risk of sensor failure. Velocity, stage,and EC data were replicated using independent sensorsat Site B, the compliance site.

The San Luis Drain is a concrete-lined canal withcontrol structures. Discharge at Sites A and B is deter-mined using direct readings of velocity and stage.Velocity data were multiplied by the channel crosssection, obtained using a theoretical relationship betweencross-sectional flow and stage based on the channeldimensions. An error correction was applied to thisrelationship to account for bed sediment accumulation inthe channel.

In large streams such as Mud and Salt sloughs andthe San Joaquin River, where control structures are notavailable, discharge is calculated using direct stagemeasurements and a stream-rating curve. The ratingcurve for a gauging station is a graphical depiction of therelation between stage and discharge. Each station-ratingcurve represents the individual characteristics of each sitewhich, in the case of a stream, may change after floodevents as a result of sedimentation or streambed erosion.These changes result in a correction or “shift” in the fixedrelationship between stage and discharge. Occasionallydownstream conditions may control the dischargecreating a “backwater” condition during which time therating curve is no longer valid. During these episodesflow measurements need to be made directly. Regular sitevisits are necessary with this type of flow monitoringstation to develop an accurate rating curve and to checkthe current stream rating.

San Luis DrainSite A

Description

The flow of agricultural drainage water entering theSLD from the Drainage Project Area is measured at SiteA. Discharge is computed from stage measured as depthof water over a sharp-crested weir.

A discharge-rating curve was developed for Site Aover the course of the first year of the GBP. Hourly stagemeasurements are recorded on a paper chart using theStevens recorder in a stilling well. The stage is checkeddaily against a staff gauge fixed to the stilling well.Weekly stage measurements using a Clausen Rule placedat the center of each weir is used for quality assurancepurposes. The discharge-rating table was developedusing these measurements.

Continuous EC data are recorded at 15-minuteintervals using an EC sensor linked to a datalogger. Thecalibration of the EC sensor is checked each month aftercleaning and any shifts in the sensor cell constantrecorded in the spreadsheet used to post-process andsummarize the EC results. The EC data are used in massbalance computations for the SLD between Sites A andB (See the Salt Mass Balance section on page 38).

Lawrence Berkeley National Laboratory staff visitedthe site monthly to inspect, clean, and calibrate the


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equipment in accordance with the Quality AssuranceProject Plan (QAPP; Entrix, Inc., 1997). More frequentvisits occurred while floodwater was conveyed by the GBP(February–July).

Data Summary

Figure 2 summarizes the mean daily flow passing Site Aduring the WY 1998. The mean flow passing Site A was60 cubic feet per second (cfs). The flow reached amaximum of 148.5 cfs on February 9, 1998, the result ofheavy rains that fell on the region during the previousweek. Flow past the site exceeded 100 cfs from February3 through April 13, and briefly in May and June.

Performance

There is no electrical power at this site. A 12-volt carbattery, recharged with a solar panel, powers the salinityprobe and datalogger. Efforts to install a cellular phonefor remote data retrieval have not been successful to dateowing to programming difficulties and power limitations.All equipment performed as required at this site andthere were no gaps in data due to equipment malfunction.

Comments

Current-meter flow measurement for quality assuranceis impractical at Site A because of the complex hydrau-lics and velocity profile immediately upstream of thesharp created weirs. There are no footbridges or bridgecrossings at appropriate distances upstream or down-stream of Site A. It is recommended that a bridge beinstalled upstream from Site A similar to the one atSite B.

It is also recommended that this site be developedfor inclusion in the Real-time Water Quality MonitoringProgram of the San Joaquin River Management Plan.This would involve the installation and calibration oftelemetry equipment. Electrical power may have to beprovided to ensure safe and reliable operation of thisequipment.

Electrical power would also support the collectionof selenium water quality samples at the same samplingfrequency as Site B. A mass balance analysis of seleniumloads at Sites A and B has shown the sensitivity of resultsto the sampling interval. Selenium samples are taken sixtimes daily at Site B and weekly composites of dailyselenium samples are taken at Site A.

31


The U.S. Geological Survey (USGS) took over theoperation and maintenance of Site A on October 1,1998. All equipment will be replaced during WY 1999.A Handar digital shaft encoder will be connected to theStevens Recorder to replace the Keller pressure sensor asthe primary stage measurement device.

Site B

Description

Site B is the downstream flow monitoring and seleniumload compliance-monitoring site on the SLD. Theperformance of GBP to manage selenium loads dis-charged into Mud Slough is assessed at this site.

Site B is located approximately 28 miles northwestof Site A, and 1.9 miles from the terminus of the SLD.

The flow of agricultural drainage water passingSite B is measured using several techniques. Velocity,stage, and salinity sensors are attached to a footbridgeacross the SLD. A nearby cantilever bridge is used forcollecting water samples.

Due to the importance of this site, duplicate stageand flow measurements are taken at Site B in case ofsensor failure. Three independent stage measurementsystems are used. There are two salinity/temperaturesensors as well.

The primary method for measuring stage is with anitrogen bubbler pressure transducer. Stage is measuredevery 15 minutes in a multi-channel datalogger locatedwithin the adjacent gauge house. The datalogger is

connected to a telephone and modem, which allowsremote acquisition of data.

Two acoustic velocity meters (AVM) are mountedon adjacent bridge piers at 20% and 80% of the averageflow depth in the SLD and aligned to face each otheracross the canal. These sensors make measurements everyminute and report a mean velocity every 15 minutes.Stage is measured as often with two types of pressuretransducers. The velocity measurements are combinedwith stage measurements to produce a discharge mea-surement. This redundancy has provided reliable andcontinuous information.

Current flow measurements are made each monthfrom the footbridge using a Marsh-McBurney flowsensor. The sensor is lowered at two-foot intervals acrossthe bridge into the water with a hand winch on a trolleymounted to the rails of the bridge. A weighted “fish” isused to align the sensor into the flow.

Lawrence Berkeley National Laboratory staffcollected raw stage and velocity data each week. Stagereadings were checked against staff gauge readings andthe daily readings adjusted in the case of a discrepancybetween sensor and staff gauge readings. LBNL staffvisited the site monthly to inspect, clean, and calibratethe equipment in accordance with the QAPP. Morefrequent visits occurred while floodwater was conveyedby the GBP (February–July).

Data summary

Figure 3 summarizes the mean daily flow passing Site Bduring the WY 1998. The average flow passing Site Bwas 63.5 cfs. Peak flow of 145.3 cfs occurred on February13, 1998. Mean daily discharge exceeded 100 cfs betweenFebruary 3 and April 12, and May 13 through 17.

Performance

A minor drift problem was observed in one EC sensordue to algae on the probe. This problem was solved inthe early part of the year by rinsing the probes in avinegar solution for 5 minutes during the monthlymaintenance site visit. This change in protocol wasadopted for all five continuously monitored sites. Theremaining sensors performed well during WY 1998.

In general, the Keller pressure transducer providedan excellent reference and deviated from the staff gaugemeasurements less than the bubbler transducer duringthe first year of monitoring. The drift in the nitrogen“bubbler” sensor was likely due to corrosion of the circuit

Grassland Bypass Project Site B

Location San Luis Drain, approx. 2 milesfrom terminus near Gustine,California

Responsibility Lawrence Berkeley NationalLaboratory

Parameters Stage, velocity, salinity,temperature

Equipment Keller pressure transducer,Design Analysis nitrogen bubblerpressure transducer, 2-Accusonicacoustic velocity meters; monthlycurrent meter readings withMarsh-McBirney velocity probe; 2-Campbell 247 electricalconductivity/temperature probes;Campbell CR10 datalogger andmodem


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Figure 3. Grassland Bypass Project Mean Daily Flow Passing Site B

board, which was discovered in November after removalof the sensor. The AVM flow sensors proved robust andreliable for the task of flow monitoring at this site.

A regression equation was developed for dischargemeasured with the AVMs and the Marsh-McBurneysensor and the following calibration constants were used:

Y = 0.8723 X+ 0.4508 October 1, 1997 through November 30, 1997

Y = 0.8916 X December 1, 1997 to present

The Marsh-McBurney velocity sensor is sensitive toalignment. A new deep-sea fishing swivel was used tocounter torsion in the cable to keep the sensor alignedduring low flow.

Comments

Due to proper management of the GBP, discharges ofwater from the GBP area to Mud Slough did not exceed150 cfs in accordance with the Use Agreement.

It is recommended that the case holding theDesign Analysis transducer and microprocessor beinstalled vertically on the wall of the shed to preventmoisture collection on the circuit board.

The U.S. Geological Survey took over the opera-tion and maintenance of Site B on October 1, 1998. Allequipment will be replaced during the WY 1999.

Comparison of Data Collected atSites A and B

Flow gains

Seepage (both into and out of the SLD), evaporation,and flow velocity can affect the relationship between thedata at Sites A and B. Comparisons made betweendischarge measurements and Clausen rule measurementsat the SLD terminus have shown good agreement.

The particle travel time1 in the SLD between SitesA and B was typically between 24 and 48 hours. Figure4 compares the flow passing Sites A and B during thesecond year of the GBP.

The flow of water recorded at Sites A and B wasvery similar during most of the WY 1998. Smallincreases in flow and salt load were measured duringOctober–December 1997 that may have been due toseepage from adjacent wetlands ponds and groundwaterthrough weep valves and cracks in the SLD’s concrete

1 The particle travel time is the time it takes for a given volume of water to move between Sites A and B and can be estimated using SLD electrical

conductivity.

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Figure 4. Grassland Bypass Project Comparison of Daily Flows Passing Sites A and B

lining. Wooden boards were added at Checks 4, 8, 11,and 17 to reduce the head difference between water inthe SLD and the adjacent wetlands and hence minimizeseepage into the SLD. The flow monitoring data suggestthat this action was effective in reducing inflow and saltimports into the SLD.

Figures 5A, 5B, and 5C compare the monthlydischarge passing Sites A and B during the WY 1998.Efforts to remedy the discrepancy were reported by theProject Drainage Coordinator:

In mid-November 1997, it was evident thatthere were some flow gains in the SLD. Thiswas determined by the higher October totalfor flow at Site B compared to Site A (seeFigure 5). Although individual daily readingswould also indicate gains, operational actionscan tend to cause daily flows to fluctuate andtherefore it is not as apparent from dailyreadings.

On December 11, 1997, a field trip indicateda possible source of the inflows was pondedwater in the Grassland wetlands adjacent toSLD at Checks 11 to 15. Field readings weremade of the wetland elevations to SLD waterlevels. Flow readings were taken with aClausen Rule on December 12, 1997 at each

of checks 11 to 17. It was determined to addboards to checks 11 to 15 to raise the waterlevel and minimize the head differencebetween the ponded wetlands and SLDwater levels. The water level in SLD was lowto allow for possible storm flow increases.

Readings on December 15, 1997 show thatthe flow gains had decreased but had notbeen eliminated. On December 30, 1997 andJanuary 6, 1998, flow readings were taken atcheck 17 to the terminus. This indicated thatalthough flow gains had been minimizedbetween checks 11 and 15, there still weregains further downstream. Boards weresubsequently added to checks 4 and 8. Inletand outlet readings on January 19 indicatethe flow gains have been minimized.

It will probably not be possible to eliminatethe gains as long as water is ponded nearSLD. The levels in the ponded water are stillhigher than the levels in SLD even with theboards added. It is assumed that the water isgetting into SLD through the weep valves inSLD lining and through cracks in the lining.On December 10 and 11, 1997, it wasobserved that water was seeping into SLD


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Figure 5A. Grassland Bypass Project Monthly Gain in Flow Between Sites A and B

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Figure 5D. Grassland Bypass Project Historic Flows Passing Sites A and B


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Site A 231 178 206 290 842 1,445 1,613 1,251 818 604 489 376

Site B 248 207 178 335 965 1,600 1,554 1,371 807 615 500 388

Monthly Limit

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Figure 6A. Grassland Bypass Project 1998 WY Selenium Mass Balance Between Sites A and B

2 Joseph C. McGahan, Grassland Bypass Project Drainage Coordinator, January 21, 1998.

through the lining above the water level inthe drain. This is evident by the level of the“wet spot on lining”.

It is unclear what the impact will be onselenium loads due to these inflows. A waterquality sample of the seepage inflow throughthe lining downstream of check 14 onDecember 10, 1997 indicated a seleniumconcentration of less than 2 ppb and an EC of3,400 micromhos. This is just one reading in28 miles. If all the seepage inflow for Octoberthrough December were at 2 ppb it wouldequate to less than 10 pounds of selenium.The final determination will have to waituntil all the data is in for Sites A and B.2

Figure 5D shows the monthly flows passing the sites forthe duration of the GBP during the WY 1998. It shouldbe noted that discrepancies in flow during the first yearof the GBP (WY 1997) were due to measurement errorswhile the equipment was calibrated and data wereverified.

Selenium Mass Balance

Flow data, when combined with continuous and discretewater quality data, can be used to compute a massbalance between two sites.

A selenium mass balance for Sites A and B for theWY 1998 is shown in Figure 6A. This was developedwith a flow-weighted average statistical method usingsame day flow and selenium load at each site.

The total quantity of selenium measured in waterpassing Site A is estimated to be 8,372 pounds, and thatpassing Site B is estimated to be 8,768 pounds. Thisindicates a gain of selenium between the sites of395 pounds and an increase of 4.7%. The difference inmonthly load of selenium between the sites is shown onFigure 6B. The monthly difference expressed as a percent-age of the selenium load at Site A is shown on Figure 6C.

Selenium samples are taken six times daily atSite B and weekly composites of daily selenium samplesare taken at Site A, leading to sampling error associatedwith statistical precision between the sites. The accuracyof the calculated selenium load at each site is alsocompromised when flows fluctuate significantly fromhour to hour and day to day.

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Figure 6B. Grassland Bypass Project Monthly Change in Selenium Load Between Sites A and B

Figure 6C. Grassland Bypass Project Monthly Change in Selenium Load Between Sites A and B

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Figure 7A. Grassland Bypass Project Comparison of Mean Monthly Salt Loads at Sites A and B

Selenium load is the product of concentration andflow. A simple average of daily or weekly concentrationstends to bias the load calculation by not considering theflow associated with each concentration value. Forexample, if low concentrations are associated with highflows then the load computations would be higher thanexpected if a simple mean was used instead of a flow-weighted mean, since the mean would be biased in thedirection of the higher concentrations.

The largest gain in selenium load occurred duringthe winter and early spring when the adjacent wetlandswere flooded. This would cause a reversal in the hydrau-lic gradient, forcing water into the drain through cracksand weep valves. It is possible that this water may havemobilized selenium from sediments into the watercolumn. However, data shows a reduction of seleniumbetween the sites during April 1998, possibly due tomicrobial uptake, adsorption to sediments, volatilization,or seepage from the SLD between the sites.

It is recommended that daily selenium analysesshould be collected at Site A to reduce the sampling andstatistical errors. There is insufficient evidence fromstatistical analysis of the data to suggest that the meanselenium load values are truly different.

Further study is needed to determine whetherwater from adjacent wetlands passing into the SLD

through cracks and weep-valves could mobilize seleniumin bed sediments.

Further research is needed to determine howgroundwater inflow, oxidation of sediment selenium, andmicrobial depuration cause a gain in selenium betweenSites A and B in the SLD. (The loss of selenium wouldsuggest microbial uptake, adsorption to sediments,volatilization, or seepage from the SLD between thesites.)

Salt Mass Balance

Figures 7A and 7B compare the salt load of water passingSites A and B during the WY 1998. Figure 7C shows thegain in salinity as a percentage of the load at Site A.

Since salinity is a conservative chemical constituent(under ideal conditions), the monthly salt load measuredat Site A should be identical to that at Site B. Anincrease in salt load would infer inflow into the SLD.

Some of the lack of correspondence between thesalt loads at Sites A and B might be associated withgroundwater seepage into the SLD. This inflow to theSLD occurs during months when the elevation of waterin adjacent wetlands is above the level of the water inSLD. The inflow may contain EC concentrations from1,000 to several thousand µS/cm. This may explain the

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increase in monthly salt load between Sites A and B.Drift in the EC sensor response can also affect thecomputation of salt load—hence the importance ofcareful and frequent recalibration of the EC sensors.

Mud SloughSite D

Description

Site D is a flow and water quality monitoring site inMud Slough located downstream from the terminus ofSLD. Sensors are mounted on a road bridge across

stabilized riverbanks. A datalogger is kept in a steelshelter, and this equipment is telemetered for remoteaccess of data.

Mud Slough collects drainage water from theGrassland Water District (GWD) as well as the VoltaWildlife Refuge. The Slough also conveys operationalspills from the Delta-Mendota Canal and CentralCalifornia Irrigation District’s Main Canal, and floodflows from Los Banos Creek.

Data summary

Figure 8 summarizes the mean daily flow passing Site Dduring the WY 1998. Mud Slough conveyed a greatamount of floodwater from wetlands and Los BanosCreek during the winter months in addition to dis-charges from GBP. The average flow passing Site D wasover 250 cfs. Total flow exceeded 500 cfs betweenJanuary 17 and 24, and from February 2 through March16, 1998. Continuous flows of more than 1000 cfsoccurred between February 8 and 28, 1998.

Performance

Site D provided good quality data throughout the WY1998. The site was in backwater conditions from Marchthrough late July. USGS staff conducted weekly currentmeter readings from the road bridge because the high

Grassland Bypass Project Site D

Location Mud Slough near GustineCalifornia, approx. 0.6 miledownstream from San Luis Drainterminus (USGS 11262900)

Responsibility United States Geological Survey

Parameters Stage, discharge, salinity,temperature

Equipment Design Analysis nitrogen pressuresensors; periodic current meterreadings; Campbell 247 electricalconductivity/temperature sensor;Cambell CR 10 data logger;modem

41


Grassland Bypass Project Site E

Location Mud Slough, approx. 6 milesdownstream from terminus of theSan Luis Drain


Parameters Stage, discharge

Equipment Staff gauge; biannual currentmeter readings

flows caused a major shift in the site rating. The existingnitrogen bubbler sensor continued to operate properly.

Comments

The U.S. Geological Survey is considering the installationof AVM sensors at this site. The U.S. Bureau of Reclama-tion (USBR), GWD, and LBNL are considering theinstallation of a real-time flow monitoring site at the GunClub Road bridge across Mud Slough, about two milesupstream of Site D.

Site E

Description

Site E is the Highway 140 bridge across Mud Slough.According to the Compliance Monitoring Plan, flowmonitoring was to be performed bi-monthly at this site.

Ungauged inflow occasionally enters the reachbetween Sites D and E, especially after winter and springrainstorms. There is insufficient information to calculateseepage losses between D and E.

Data summary

Flow was measured on December 16, 1997. FromFebruary through August 1998, the site was inundatedwith floodwater that was backed up from the SanJoaquin River. High flows left the stream channel,eroded banks, and deposited sediment and debris. It wasnot possible to accurately measure flow at this site.

Performance

The site was flooded for over seven months. The siteremained accessible and existing equipment was notdamaged.

Comments

Measurement error masks any difference in load betweenSites D and E. The accuracy of the flow measurement isapproximately 2% at Site D and 5% at Site E, dependingon flow conditions. Water quality sampling errors couldbe in the order of 2–5% with additional error introducedduring analysis. Travel time between the sites is anothervariable that adds uncertainty to load calculations. Flowgains and seepage losses that occasionally occur betweenSites D and E are unquantified. A mass balance is notpossible unless the flow and water quality of all inflowsare accounted for.

Commencing September 1998, USGS, undercontract with USBR, will measure flow and EC at Site Efour times per year. The field visits will coincide with thequarterly biota and sediment sampling at the same sitesbeing conducted by the Department of Fish and Game,the U.S. Fish and Wildlife Service, and USBR. Up tofour sets of flow and electrical conductivity measure-ments and water quality samples will be collected at bothSites D and E, (i.e., 2 samples daily at both sites for 2days). The samples will be analyzed by the Central ValleyRegional Water Quality Control Board.

Salt SloughSite F

Description

Site F is the flow and water quality monitoring site inSalt Slough. USGS is responsible for operating, main-taining, and retrieving data from this site. The water inthis channel is derived from wetlands and non-GBPfarmland.

Grassland Bypass Project Site F

Location Salt Slough near Stevinson,California (USGS 11261100)



Equipment Design Analysis nitrogen bubblerpressure transducer; periodiccurrent meter readings; Campbell247 electrical conductivity/temperature sensor; Cambell CR10 data logger


42

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Figure 9. Grassland Bypass Project Mean Daily Flow Passing Site F in Salt Slough

Analytical equipment at the site includes a nitro-gen bubbler sensor and an electrical conductivity sensor.

Discharge ratings are performed from a cable wayat Site F.

Data summary

Figure 9 summarizes the daily flow passing Site F duringthe WY 1998. The average flow of water passing Site Fwas 270 cfs during the WY 1998. The peak flow of765 cfs occurred on February 17, 1998. Continuous flowsin excess of 500 cfs occurred between February 4 andMarch 13, and again from March 26 to 29.

Due to excess rainfall, regional flood and agricul-tural drainage water that exceeded the capacity of theGBP were released into Salt Slough between February 2and February 28, 1998. The average flow during this 26-day emergency operation was 665 cfs.

Performance

Equipment at this site performed without any apparentproblems during the WY 1998. There was a brief breakin data between October 6 and 15, 1997 due to equip-ment damage. Rip-rap was mistakenly dropped on theorifice line. Vandals damaged the EC probe and caused aloss of data between March 23–30, 1998.

The site remained accessible and was underbackwater conditions between February 3 and July 20,1998. USGS staff made weekly current meter readingsdue to these conditions caused by flooding from the SanJoaquin River.

Comments

Due to backwater conditions and large shifts in stage,AVM sensors would not be practical at this site.

San Joaquin RiverSite N

Grassland Bypass Project Site N

Location San Joaquin River at CrowsLanding, California (USGS11274550)



Equipment Design Analysis nitrogen bubblerpressure transducer; periodiccurrent meter readings; Campbell247 conductivity/temperatureprobes; Campbell CR 10 datalogger; modem

43


Description

Site N at Crows Landing on the San Joaquin River is aflow gauging site established by the California Depart-ment of Water Resources (DWR) in the 1960s. Thelocation is not ideal, being close to a bend in the River.The USGS is currently operating and maintaining thissite. In 1997, a gauge house was installed on the northbank to improve accessibility and safety. A nitrogenbubbler continuous sensor is used to measure stage. Anew discharge-rating curve for this site was developed byUSGS in 1997. Current meter readings are taken everysix weeks by USGS staff to verify the stage-dischargerelationship.

Data summary

Figure 10 summarizes the mean daily flow passing SiteN during the 1998 Water Year. The average daily flowpassing this site was about 6,775 cfs. The maximum flowoccurred on February 11, 1998, with over 24,300 cfs offloodwater. Continuous flow in excess of 10,000 cfsoccurred between February 5 and March 10, 1998, andfrom March 27 through July 3, 1998. Flows exceeded20,000 cfs for eleven days in February 1998.

Performance

Existing equipment malfunctioned in October 1997 andagain in August 1998. The equipment was repairedwithin two weeks of each failure and flow rates wereestimated. Though the site is rated poor due to channelconditions, the data are considered to be reliable by theUSGS and the CVRWQCB.

Comments

The logistics for making current meter readings at thissite are very difficult at high stages.

Other Monitoring SitesSites J, K, L, and M (Camp 13, Agatha, San Luis, andSanta Fe canals, respectively) are primarily water qualitysites in the Monitoring Plan since the role of these sitesis to ensure that no agricultural drainage water enterseither north or south Grassland Water District chan-nels. Flow measurements were made at these sites byGrassland Water District staff using a number oftechniques and were included in the monthly monitor-ing reports.

0

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Figure 10. Grassland Bypass Project Mean Daily Flow Passing Site N

(San Joaquin River at Crows Landing)


44

Excess rainfall during February 1998 created highflows within the Drainage Project Area that exceeded thecapacity of the Grassland Bypass. The storm dischargeswere managed in accordance with the Storm Event Plan(Grassland Area Farmers, 1997). On February 3, 1998,the Drainage Coordinator decided to start releases offloodwater into Grassland Water District through theAgatha and Camp 13 canals. The decision was madebecause of heavy rainfall the previous day and evening,the likelihood of increased rainfall, and the fact thatPanoche/Silver Creek flood waters were expected at theheadgate of the Grassland Bypass within 24 hours.Beginning at 1300 hours on February 3, 1998, releases of50 cfs were commenced to the Agatha Canal. Peak flowof 95 cfs occurred from February 8 to 10, 1998. The totaldischarge was estimated to be 3,400 acre-feet. About500 acre-feet of floodwater were discharged into theCamp 13 Canal during February.

Figure 11 summarizes the daily discharges offloodwater into the Agatha and Camp 13 canals.

Project Impacts on theSan Joaquin RiverIn order to assess the effect of GBP on salinity in theSan Joaquin River, an analysis was developed to isolatethe effects of GBP from other activities potentiallyaffecting salinity concentrations in the Basin. Since onlydrainage from GBP is relevant to any project-relatedchanges in salt load on the San Joaquin River, theanalysis was cast in terms of theoretical dilution waterneeded to bring the GBP discharges to the Vernalisseasonal EC objectives.

The salinity objectives for Vernalis are1,000 mmhos/cm (640 mg/L) in the winter months(September–March) and 700 mmhos/cm (448 mg/L) inthe summer months (April–August).

Figure 12 shows the theoretical volume of waterthat would be needed to dilute the combined salt loadsfrom the Drainage Project Area (measured at Site B),Mud Slough, and Salt Slough to meet the Vernalisstandards. This analysis does not take into account any of

0

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-feet

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Figure 11. Grassland Bypass Project 1998 Water Year

Discharge of Floodwater to Wetlands Channels

45


-

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Acre

-feet

From Mud & Salt Sloughs (Sites D & F) From the Grassland Bypass Project (Site B)

Figure 12. Grassland Bypass Project Volume of Dilution Water (@100mg/L TDS) Required to Reduce

the Concentration of Drainage Water to Meet the Vernalis TDS Objectives

the other operational criteria, nor does it consider salinitycontributions to the River other than those derived fromthe Grasslands Basin. The value of the analysis is that itpermits a much clearer “with” and “without” projectcomparison with prior year hydrology, in terms (waterquality releases from a reservoir) meaningful to waterusers and managers.

The assimilative capacity analysis considers thetotal volume of dilution water (assumed to have a salinityof 100 ppm) that would be needed to reduce the drain-age water alone to the salinity objective. Note that themonthly volume of dilution water is highly dependent onthe 100-ppm assumption. Note also that the relationbetween dilution water quality and required volume isnon-linear.

Figure 12 shows the dilution requirement for thecurrent project year WY 1998 compared to water years1985 through 1997. In this sequence of years, 1986,1995, 1996, and 1997 were classified as wet years, similarto WY 1998. In each of these years the water districtswere supplied with 100% of their contract water supply.Drought conditions prevailed between 1987 and 1992with water supplies varying from 100% supply in 1987 to25% in 1992. A comparison of the grey shaded area for

each water year in Figure 12 shows that the dilutionrequirements for salt loads from the GBP area weresimilar to those during the drought years during the firstyear of the GBP, indicating an overall reduction in saltloading to the River as a result of implementation of theProject. The blue shaded area in Figure 12 represents thedilution requirements for salt loads generated by theentire Grasslands watershed that includes agriculturalareas, wetlands, and uncontrolled runoff from the CoastRange watersheds. Though the CVP delivered a fullwater supply during the WY 1998, the volume of waterneeded to dilute the salt load from Mud and Salt sloughsthis year appears to be less than that needed in previouswet years (1986, 1993–1997).

Sources of DataEntrix, Inc. 1997. Quality Assurance Project Plan for the

Compliance Monitoring Program for the Use andOperation of the Grassland Bypass Project (FinalDraft). Prepared for the U.S. Bureau of Reclama-tion. Sacramento, CA. June 20, 1997.

Grassland Area Farmers. 1997. Storm Event Plan,August 25, 1997.


46

Grassland Area Farmers. 1998. Grassland Bypass ProjectStorm Event Operations, February 1998.

San Francisco Estuary Institute. 1997–1998. GrasslandBypass Project Monthly Data Reports October1997 through September 1998. http://www.sfei.org/grassland/reports/gbppdfs.htm

U.S. Bureau of Reclamation and the San Luis & Delta-Mendota Water Authority. 1995. Agreement forUse of the San Luis Drain. Agreement No. 6-07-20-w1319, November 3, 1995.

U.S. Bureau of Reclamation, et. al. 1996. ComplianceMonitoring Program for Use and Operation of theGrassland Bypass Project, September 1996. U.S.Bureau of Reclamation, Mid-Pacific Region,Sacramento, CA.

Data SourcesGrassland Bypass Project Homepage:

http://www.mp.usbr.gov/mp150/grassland/HomePage/Homepage.html.

47

Chapter 4: Water Quality Monitoring

Chapter 4

Water QualityMonitoring

Al VargasCentral Valley Regional Water Quality Control Board


48

The monitoring program, for the Grassland BypassProject (GBP), including water quality monitoring, isdescribed in detail in Compliance Monitoring Program forthe Use and Operation of the Grassland Bypass Project(USBR et al., 1996). This chapter provides a summary ofthe water quality monitoring program, modifications tothe plan for the second year of operation of the GBP(October 1, 1997 to September 30, 1998) and waterquality trends observed from two years of operation ofthe GBP. Detailed discussion of water quality results ofindividual monitoring sites will not be provided as theSan Francisco Estuary Institute (SFEI) has this informa-tion in another report (SFEI, 1999)

Monitoring ProgramThe Central Valley Regional Water Quality ControlBoard (CVRWQCB) has an on-going water qualitymonitoring program related to regulatory activities foragricultural subsurface drainage from the Grasslandwatershed. The water quality monitoring program for theGBP was an adaptation of the CVRWQCB’s monitor-ing program. The CVRWQCB was responsible for mostof the water quality sampling with assistance from thePanoche Water District (under contract with the SanLuis & Delta-Mendota Water Authority; SL&D-MWA) and the U.S. Geological Survey (USGS). ThePanoche Water District collected weekly grab samples atSites A, J, K, L, L2, M2, and M and the USGS collectedbimonthly samples at Sites D and E. Samples wereprocessed by the CVRWQCB and analyzed by itscontract laboratories. The CVRWQCB conductedquality assurance (QA) reviews of the data beforesubmitting them to the SFEI for reporting. However, allCVRWQCB data are provisional and subject to changeuntil the CVRWQCB approves the report on the wateryear (WY) 1998 monitoring results.

Monitoring Objectives

The water quality monitoring program was designed toprovide data for evaluating compliance with commit-ments in the Use Agreement and associated documents.The commitments included:

• Maximum monthly and annual selenium loadlimits on discharges.

• No degradation of the San Joaquin River waterquality relative to the no project condition.

• Cease discharge of agricultural subsurfacedrainage to the wetland channels.

• Manage flows in the San Luis Drain (SLD) soas to not mobilize channel sediments.

The Monitoring Program was also designed to verify thevalidity of assumptions expressed in documents associ-ated with the GBP. The assumptions included:

• The GBP is expected to result in seleniumconcentrations less than 2 mg/L in approxi-mately 93 miles of wetland water supplychannels.

• The increased frequency of exceeding seleniumwater quality objectives in Mud Slough (north)would be offset by a reduction of violations inSalt Slough.

In addition, the Monitoring Program was intended toprovide data to be used to assess spatial and temporaltrends in water quality parameters of concern and tocharacterize habitats in which biological samples werecollected.

Sampling Locations

Monitoring was to be conducted in four areas; the SLD,Mud Slough (north), the San Joaquin River, and theGrassland wetland water supply channels, including SaltSlough. Table 1 summarizes the Monitoring Program andsampling locations are depicted in Figure 1 in Chapter 1.

Frequency of Sampling

The frequency of sampling is outlined in Table 1. Dailycomposite samples were collected at Site B (dischargeform the SLD) and at Site N (San Joaquin River atCrows Landing). At Site B, daily selenium concentrationdata along with continuous flow data were used tocalculate daily selenium load discharge. At Site N, dailysamples were collected to allow the CVRWQCB toevaluate progress toward compliance with Basin Planwater quality objectives. The compliance date for theselenium water quality objective is October 1, 2005. Theobjective is based on a 4-day average concentration.Thus, consecutive daily samples were required at this site.

The frequency of sampling for Site A was in-creased from a weekly grab to a weekly composite madeup from daily auto-samples. Selenium data from this sitewill be used to improve the selenium load evaluationbetween Sites A and B.

The remaining sites were sampled on a weeklybasis, with the exception of Site E. Site E was sampled

49

Chapter 4: W

ater Quality M

onitoring

Location Site Description Purpose Analytical Parameter FrequencySamplingMethodology

San LuisDrain

A inflow to SLD water quality of drainage inflow(Se and TSS). Se mass balancein SLD

SeSe, Se (diss), B, TSS

weekly compositeweekly

auto-samplermid-channel,depth integrated

B discharge fromSLD

water quality of drainagedischarge (se load calculationsediment mobilization provisionevaluation)

SeSe, Se (diss), B, EC, TSS

daily compositeweekly

auto-samplermid-channel,depth integrated

MudSlough (N)

C upstream of SLDdischarge

Mud Slough (N) water qualityprior to receiving drainagedischarges

Se, B, EC weekly grab

D downstream ofdischarge

Mud Slough (N) water qualityas impacted by drainagedischarge

Se, B, EC weekly mid-channel,depth integrated

E at Hwy 140 selenium fate evaluation Se, B, EC bimonthly equal width,depth integrated

I back water water quality impact of MudSlough (N) flooding in KestersonRefuge

Se, B, EC annually N/A

WetlandChannels

F Salt Slough water quality of habitat and totrack improvements in formerdrainage conveyance channel


J Camp 13 verify no discharge of drainageprovision


K Agatha Canal verify no discharge of drainageprovision


L San Luis Canal water quality of wetland watersupply channel


M Santa Fe Canal water quality of wetland watersupply channel


SanJoaquinRiver

G at Fremont Ford(upstream ofdrainage inflow)

track improvements in formerdrainage conveyance channeland characterize water qualityof habitat


H at Hills Ferry(downstream ofdrainage inflow)

water quality of river mostimpacted by drainage dischargeand to characterize waterquality of habitat


N at CrowsLanding(downstream ofMerced Riverconfluence)

characterize water quality ofhabitat.comparison with Basin Planwater quality objectives.

SeSe, B, EC

dailyweekly

auto-samplergrab

Table 1. Summary of Water Quality Monitoring Plan


50

bimonthly concurrently with Site D by the USGS as partof the selenium mass balance study.

Sampling Methodology

Three types of sampling techniques were utilized depend-ing on the frequency of sampling and data needs: auto-sampler, mid-channel depth integrated, and grab samplefrom channel bank. Auto-samplers were used to collectdaily composite samples because of the remoteness of theproject site and frequency of sampling. At Sites A, B, andD, structures such as a bridge or platform over thechannels permitted the collection of mid-channel, depthintegrated samples. At other sites, a grab sample from thestream bank was collected. However, complete mixing wasexpected for dissolved constituents at all sampling sites.

Modifications to theWater QualityMonitoring ProgramDuring the first year of the GBP several issues wereresolved with respect to the water quality monitoringprogram. These modifications and clarifications to themonitoring program were discussed in the first AnnualReport (USBR, 1998). During the second year of theGBP two additional issues arose; the sampling locationfor two wetland channels (San Luis Canal—Site L andthe Santa Fe Canal—Site M) and the frequency ofsampling at the inflow to the SLD (Site A).

Wetland Channels SamplingLocations

Sites L and M were selected based on historic sampling bythe CVRWQCB. The CVRWQCB had selected thesesites for monitoring water quality when agriculturaldrainage was conveyed through these channels. The“plumbing” of the wetland channels has since been alteredas a result of the GBP along with the termination of anagreement for the use of the Porter-Blake Bypass. As aresult, Sites L and M are not appropriate locations tomonitor water quality of these two channels as thesechannels converge upstream of Sites L and M and aresubject to mixing (Figure 1). A monitoring locationupstream of the convergence would allow for betterassessment of the sources of selenium in these channels.This issue was brought before the Data Collection andReporting Team (DCRT) and Sites L2 and M2 (Figure 1)were selected. It was agreed that there would be concurrent

sampling for several months for Sites L, M, L2, and M2.After this period, Sites L and M would be deleted fromthe program and replaced with Sites L2 and M2. Table 2is a tabulation of the concurrent data. No analysis has beenperformed on these data at this time.

Frequency of Sampling at Site A

One of the objectives of the Monitoring Program was toevaluate selenium mass balances whenever the datapermitted. Initial efforts of evaluating selenium fateusing a mass balance approach between Sites D and Ewere inconclusive. One of the alternatives discussed bythe DCRT was a selenium mass balance approachbetween Sites A and B. Site B is subject to a high degreeof study as continuous flow and conductivity measure-ments are collected along with daily composite (6 sub-samples per day) water samples for evaluation of sele-nium. Additionally, the assessment of sediment accumu-lation in the SLD and selenium content of the sedimentaffords the opportunity of evaluating the fate of seleniumin the SLD. Flow is also monitored continuously at SiteA, but grab water samples are collected once per week.

It was the general opinion of DCRT members thatweekly grab samples from Site A would not provide theaccuracy necessary to evaluate selenium mass balancebetween Sites A and B. The DCRT decided on increas-ing the sampling frequency from a weekly grab to aweekly composite. The modification to the MonitoringProgram called for collection of daily samples with anauto-sampler. The auto-sampler is serviced weekly byrepresentatives for the SL&D-MWA. Labeled daily,samples are relinquished to staff of the CVRWQCB whothen prepare a weekly composite by taking equal volumesof the daily samples. The compositing of the dailysamples into a weekly composite is expected to provide abetter estimate of the mean weekly selenium concentra-tion as compared to weekly grab samples. Table 3 presents

L L2 M M2

8/12/98 2.0 1.6 1.6 2.38/19/98 3.0 3.3 1.8 1.78/26/98 1.8 1.5 1.4 2.59/2/98 1.5 1.4 1.8 2.69/9/98 1.9 1.4 1.7 2.79/16/98 1.2 1.2 1.2 1.29/23/98 1.4 1.6 1.6 1.29/30/98 1.1 1.0 1.1 1.1

Table 2. Selenium Concentrations at

Sites L, L2, M, and M2 (µg/L)

51


results for electro-conductivity (EC) measurements andselenium concentrations of the composite sample andcorresponding grab sample. No analysis of the datapresented in Table 3 was conducted to assess the accuracyof selenium load calculation using the two types of data.

Water Quality TrendsDetailed water quality data for each monitoring site werepresented in Grassland Bypass Project Annual Narrativeand Graphical Summary, October 1997 to September 1998(SFEI, 1999). Thus, this presentation will be limited tomajor water quality trends and findings for the first twoyears of operation of the GBP. Of primary interest wasthe high selenium load discharged as compared to the

Henry Miller Rd

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der

Ave

(H

igh

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is D

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is C

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M

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Figure 1. Location of Monitoring Sites on the San Luis and Santa Fe Canals

first year of the GBP and the resultant selenium concen-trations in the San Joaquin River. Also discussed is thecontinued exceedances of selenium water quality objec-tives established in the Water Quality Control Plan forthe Sacramento/San Joaquin River Basins (Basin Plan;CVRWQCB, 1996) in the wetland channels, thedistribution of selenium between solid and dissolvedphase, trends in total suspended solids (TSS) in theSLD, and water quality trends in Mud Slough (north).

San Joaquin River

Figure 2 depicts selenium concentrations in the SanJoaquin River at monitoring Sites G, H, and N forWY 1997 and 1998. A water year is defined as the


52

Table 3: Composite and Grab Electrical Conductivity (EC) and

Selenium for Site A

EC (µmhos/cm) Selenium (µg/L)

Composite Weekly Grab Composite Weekly Grab

5/12/98 5400 3740 97 62.85/20/98 5280 5930 1205/27/98 5990 5490 120 1146/2/98 5740 6000 107 92.96/10/98 5100 5370 97.8 1036/17/98 5120 4880 89.2 84.26/24/98 4520 4420 66.6 51.27/1/98 4410 4630 49.8 52.87/8/98 4480 4240 47.07/15/98 4110 4180 44.0 47.28/19/98 3930 3780 38.6 32.68/26/98 4380 4760 44.6 57.59/2/98 2800 4400 50.19/15/98 4170 3780 46.39/22/98 4100 3040 43.0 25.49/30/98 3890 4510 67.4

WY 1998WY 1997

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/98

Site G (Fremont Ford)—upstream Site H (Hills Ferry)—downstream

Site N (Crows Landing)—downstream of Merced R.

5 µg/L Se water quality objective

Figure 2. Selenium Concentrations in the San Joaquin River

WY 1997 and 1998

53


period from October 1 to September 30 of the followingyear. Site G is located at Fremont Ford, upstream ofMud Slough (north) inflow to the San Joaquin River.Because this site is located upstream of drainage dis-charges (except during storm events when drainage isrouted to Salt Slough), selenium concentrations are thelowest of the three monitoring sites. Site H at Hills Ferryis downstream of Mud Slough (north) inflow to the SanJoaquin River and upstream of tributary inflows to theSan Joaquin River which dilute selenium concentrations.Consequently, this site represents the location in theRiver most impacted by the GBP. Selenium concentra-tions were the highest at this monitoring site. Site N isthe farthest downstream monitoring site on the river andis downstream of the Merced River inflow to the SanJoaquin River. Merced River inflows contain lowconcentrations of selenium which dilute the seleniumintroduced into the river as a result of the GBP. Sele-nium concentrations at this monitoring site wereintermediate between the background Site G and Site H.

The Water Quality Control Plan for the Sacra-mento River and San Joaquin River Basins (Basin Plan)has a schedule for compliance with the 5 µg/L (4-dayaverage) selenium water quality objective. The compli-ance date is either October 1, 2005 or October 1, 2010,depending on location and type of water year (wet, dry,

etc.). The water quality objective is depicted in Figure 2for comparison purposes. The selenium objective wasfrequently exceeded during WY 1997 for the two sitesdownstream of drainage discharges (H and N; Figure 2).This was especially true for the period between Februarythrough July when the selenium objective was exceededall the time at Site H. In contrast, the selenium objectivewas never exceeded during this period in WY 1998 forany of the San Joaquin monitoring sites.

Figure 3 depicts the monthly selenium loadsdischarged at Site B. This figure also shows the monthlyselenium load values specified in the Use Agreement.These monthly load values were exceeded from Februarythrough June of both WYs. However, the exceedanceswere greater in WY 1998 and in fact there was a 40 per-cent greater selenium load discharged in WY 1998 ascompared to WY 1997 for the period between Februarythrough August (7,762 pounds in WY 1998 versus 5,561for WY 1997). Despite the greater selenium loaddischarged in WY 1998, selenium concentrations weregenerally lower in WY 1998, as previously noted. Theselenium water quality objective for the San JoaquinRiver, for which compliance is required by October 1,2005 (5 µg/L based on a 4-day average), was rarelyexceeded in WY 1998 even at the monitoring site mostimpacted by the GBP.

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Figure 3. Monthly Selenium Load Discharged from Site B


54

The better water quality in the San Joaquin River,with respect to selenium, in WY 1998 as compared toWY 1997, can be attributed to the assimilative capacityof the River. Both WY 1997 and 1998 were classified aswet years according to the San Joaquin River Basin 60-20-20 Index. However, in WY 1997 rainfall occurredprimarily early in the season while in WY 1998 therainfall was more evenly distributed and extendedunusually late into the spring. This resulted in runoffpatterns as seen in Figure 4 for discharge at the SanJoaquin River at Newman. The USGS gauging site forthe San Joaquin River at Newman is located 0.1 miledownstream of the Merced River inflow. The cumulativedischarge from February through August was 2.5 timesgreater in WY 1998 than in WY 1997 (4 million acre-feet versus 1.6 million acre-feet).

Wetland Channels

Selenium concentrations in the wetland channels (SitesL and M) are depicted on Figure 5 for WY 1997 and1998. In the first annual report of the GBP (USBR,1998), it was noted that the selenium water qualityobjective of 2 µg/L for wetland water supply channels

was frequently exceeded at Sites J, K, L, and M. This wasalso observed in WY 98. Exceedances which occurredduring February 1998 are attributable to releases ofcommingled storm water and GBP agricultural subsur-face drainage to the Agatha Canal. The Agatha Canal isa supply canal of the Grassland Water District and priorto the GBP, agricultural subsurface drainage was dis-charged to this channel. Water discharged to the AgathaCanal makes its way to the San Luis and Santa Fe canals.The Grassland Area Farmers (GAF) have prepared areport addressing the management of storm flows andagricultural drainage during the February 1998 stormevent (GAF, 1998).

As a result of the observations in WY 1997, theCVRWQCB conducted an investigation to identifysources and initiate action to achieve compliance withthe water quality objectives for the wetland channels. Inaddition to commingled drainage and storm runoffduring major storm events, other potential sources ofselenium in wetland channels include supply water, otheragricultural subsurface drainage from outside of the GBParea, and groundwater seepage. Results of this investiga-tion are discussed in a CVRWQCB draft report(CVRWQCB, 1999).

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Figure 4. Monthly Water Discharge in the San Joaquin River at Newman

55


Total Versus Dissolved Selenium

During the development of the Monitoring Plan, it wassuggested that both total and dissolved selenium concen-trations be evaluated at the SLD. This was proposed inorder to gain an understanding of the partitioning ofselenium between the solid and dissolved phases. Toaccomplish this, paired samples were collected at Sites Aand B. One of the paired samples was prepared fordissolved selenium analysis by filtering a small volume(25 to 50 ml) in the field with a syringe-filter (0.45 µm)cartridge mechanism while the second sample wassubmitted for total selenium analysis.

A time-series plot of the difference between totaland dissolved selenium is depicted in Figures 6A and 6Bfor Sites A and B, respectively. If selenium is in thedissolved phase exclusively, there is an equal probabilitythat the difference between total and dissolved seleniumwould fall above and below zero. In other words themedian of the difference between total and dissolvedselenium would be zero. The magnitude of the deviation

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from zero is an indication of the sampling and analyticalerror. Inspection of Figure 6A (Site A) appears to showthat most of the differences are greater than zero, whilefor Site B the differences appear to be equally distributedabove and below zero. The distribution of the data isbetter summarized in the box-wisker plots of thedifference of total and dissolved selenium (Figure 7). ForSite A, 75% of the data are greater than zero, suggestingthat some of the selenium is associated with the sus-pended solid phase. For Site B, the median is zeroindicating that half of the data are above and half belowzero, or all of the selenium is in the dissolved phase.

Statistical analysis of the data was then conducted totest the hypothesis that there is no difference between totaland dissolved selenium; in other words, all of the seleniumis in the dissolved phase. First the data were tested fornormality using the probability plot correlation coefficientmethod (Helsel and Hirsch, 1992) in order to determinethe appropriate statistical procedure (parametric or non-parametric). Figures 8A and 8B show the probability plotsfor Sites A and B, respectively. Normally distributed data


56

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Figure 6B. Site B—Time Series Plot of Total Minus Dissolved Selenium

57


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will fit a linear relationship and thus have correlationcoefficients close to 1. The correlation coefficient for thedistribution is evaluated for its deviations from linearity.Results of the test are summarized on Figures 8A and 8B.The null hypothesis was rejected at α equal 0.05 (the dataare not normally distributed). The nonparametricWilcoxon signed-rank test was then used to test thehypothesis that the there is no difference between total ordissolved selenium (selenium is exclusively in the dissolvedphase). The null hypothesis was rejected for Site A andnot rejected for Site B at α equal 0.05.

At the inflow to the SLD a small amount of thetotal selenium is associated with the solid phase and atthe outflow it is exclusively in the dissolved phase. Thelack of solid phase associated selenium at the outflowfrom the SLD is probably due to settling out of the solidphase and associated selenium. It is not readily apparentfrom Figure 6A if solid phase associated selenium iscontinuously present or associated with storm events orother seasonal factors. Assuming that solid phaseassociated selenium is present continuously, then themedian of 0.9 gives an indication of the amount of solidphase associated selenium entering the SLD.

In view of these findings, the DCRT will need toassess the significance of the small amount of solid phaseassociated selenium flowing into the SLD, the lack ofsolid phase associated selenium in the discharge in termsof the GBP objectives and commitments, and the needto continue collecting these data.

Total Suspended Solids

One of the commitments for the use of the SLD is tomanage drainage so as not to mobilize sediments in theSLD. In order to verify compliance with this commit-ment, center-of-channel depth-integrated samples arecollected weekly at the inflow to the SLD (Site A) and atthe discharge (Site B). Some of these samples arecollected concurrently (on the same day) but for the mostpart samplings are conducted on different days for thetwo sites. A monitoring program for the evaluation ofcompliance with this commitment would require takinginto consideration travel times between these two sites.An effort of this level is beyond the resources of theGBP. Trends in TSS concentrations at both sites over thelong-term, however, can provide information regarding


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Figure 8B. Probablility Plot for Site B—Total Minus Dissolved Selenium

59


compliance. The TSS data depicted in Figure 9 show thegeneral trend that TSS is lower in the discharge than inthe inflow. This suggests that water velocities are suchthat sediments are being deposited in the SLD andscouring and mobilization of SLD sediments are notoccurring. Data presented in the previous section (totalversus dissolved selenium) also support that the SLD isbeing operated so as to cause sediments to be depositedrather than to mobilize drain sediments.

From Figure 9, it is also apparent that TSSconcentrations were generally higher in WY 1998 thanin WY 1997. Due to the high frequency of stormsgenerating high volume of runoff in WY 1998 and themanagement of these flows by the GAF to minimizedischarges to the wetland channels, high discharge ratesapproaching the capacity of the Grassland Bypasschannel occurred in WY 1998. These flows were routedthrough the SLD and contained high concentrations ofsediments which contribute to the TSS measured in theSLD. High levels of runoff were recorded in WY 1998from February through June.

Mud Slough (North)

Results of weekly grab sampling for selenium in MudSlough (north) are depicted in Figure 10. Selenium

concentration distributions as a function of time weresimilar for both WYs. Selenium concentrations are lowestfrom the fall through early winter (non-irrigation period)and highest during the irrigation period which com-mences in the mid winter (pre-plant irrigation) and laststhrough the summer. This observation is consistent withthe monthly selenium load discharges depicted on Figure3 and the volume of drainage discharged as a function oftime depicted on Figure 3 in Chapter 3. Water quality ofMud Slough (north) downstream of the SLD is domi-nated by the drainage discharge. Upstream of thedrainage discharge, the concentration of selenium wasalways below 2 µg/L (SFEI, 1999). For comparisonpurposes, the 5 µg/L selenium water quality objectivewhich applies October 1, 2010 for Mud Slough (north) isnoted on Figure 10. The selenium water quality objectivewas rarely met.

ConclusionsTwo years of GBP monitoring have shown that seleniumconcentrations in the San Joaquin River are a function oflocation in the River with respect to discharge points andtributary inflows and of the assimilative capacity of theRiver. The lowest selenium concentrations in the SanJoaquin River are upstream of Mud Slough (north)

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60

Figure 10. Weekly Grab Selenium Concentration in Mud Slough (north) for WY 1997 and 1998

inflows. The highest selenium concentrations are down-stream of Mud Slough (north) inflow and upstream oftributary inflows to the San Joaquin River. The data alsoshowed that selenium load limits may be exceeded andyet selenium water quality objectives achieved in the SanJoaquin River. Whether or not selenium water qualityobjectives are met in the San Joaquin River depends onthe assimilative capacity of the River.

A number of sources contributed to the violation ofselenium water quality objectives in the wetland channels.These include agricultural drainage outside the GBP andcommingled storm water and agricultural drainage fromthe GBP. The CVRWQCB is developing control actionsto reduce selenium concentrations in the wetland channels.

Drainage entering the SLD contains a smallamount of selenium associated with the solid phase. Thissolid phase associated selenium appears to settle out intothe SLD before reaching the outflow. Selenium at theoutflow of the SLD is exclusively in the dissolved phase.The TSS data suggest that sediment and other solids areaccumulating in the SLD and the commitment not tomobilize sediments is being complied with.

The water quality of Mud Slough (north) down-stream of the SLD inflow is governed by the drainagedischarge and fluctuates widely.

ReferencesCVRWQCB. January 1999. Draft, Review of Selenium

Concentrations in Wetland Water Supply Chan-nels in the Grassland Watershed (Draft).

Grassland Area Farmers (GAF). 1998. Grassland BypassProject Storm Event Operations, February, 1998.April 10, 1998.

Grassland Area Farmers (GAF). 1999. Memorandum—Draft Storm Event Plan. January 15, 1999.

Helsel, D.R. and R.M. Hirsch. 1992. Statistical Methodsin Water Resources. Studies in EnvironmentalScience 49. Elsevier Publishers

San Francisco Estuary Institute (SFEI). 1999. GrasslandBypass Project Annual Narrative and GraphicalSummary, October 1997 to September 1998.Richmond, CA.

U.S. Bureau of Reclamation et al. 1996. ComplianceMonitoring Program for the Use and Operation ofthe Grassland Bypass Project, September 1996.U.S. Bureau of Reclamation, Mid-Pacific Region,Sacramento, CA.

U.S. Bureau of Reclamation. 1998. Grassland BypassProject Annual Report. October 1, 1996 throughSeptember 30, 1997. U.S. Bureau of Reclamation,Mid-Pacific Region, Sacramento, CA.

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61

Chapter 5: Toxicity Studies

Chapter 5

BiomonitoringProgram for theSan Luis Drain

Discharge: ToxicityStudies

Ronald M. Block, Josh Gravenmier, and Jeffery KaneBlock Environmental Services


62

IntroductionThe Grassland Bypass Project (GBP) toxicity monitoringprogram was implemented to evaluate potential adverseeffects to test organisms from agricultural drain waterwhen conveyed through the San Luis Drain (SLD; SiteB) to Mud Slough (Site D) and removed from SaltSlough (Site F). An evaluation was also made for MudSlough (Site C) above the influence of the SLD. Eachsite was compared with responses produced from ambientcontrol water (Delta Mendota Canal). The data can thenbe used to integrate potential contaminant exposuresboth temporally and spatially within the Project area.

The toxicity monitoring program combinedmonthly controlled laboratory testing with a single directexposure (in situ) field test. These tests were conductedby Block Environmental Services (BES) BioassayLaboratory Division, under the guidance of the San Luis& Delta Mendota Water Authority and with directquality assurance/quality control (QA/QC) assistancefrom the U.S. Environmental Protection Agency(USEPA). Selenium and sulfate concentrations were alsodetermined from water samples collected during eachtoxicity testing sampling event. These chemical analyseswere performed by the U.S. Bureau of Reclamation(USBR). Each of the toxicity tests was performed usingthree separate grab samples collected on Day 0, Day 3,and Day 5 of the 7-day testing period. The 1997–1998annual data are also compared with the 1996–1997annual data, where possible.

Materials and MethodsThe laboratory toxicity tests evaluated three differentspecies using short term chronic testing procedures(USEPA, 1987; 1994). Grab samples were taken fromSites B, C, D, F, and the Delta Mendota Canal (DMC)for each monthly testing period. The test speciesincluded the freshwater alga (Selenastrum capricornutum),the fathead minnow (Pimephales promelas), and thedaphnid invertebrate (Daphnia magna). Each test wasperformed under screening conditions (100% sampleversus the DMC ambient control). All toxicity testingresults were analyzed using the EcoAnalysis, Inc.software program Toxicity Information ManagementSystem (TOXIS, Version 2.5) which utilized the flow-chart for statistical analysis outlined by USEPA for thesetests (USEPA, 1994). TOXIS was used to determine ifthere was a statistically significant reduction (p<0.05) inthe site test response versus the ambient control responseduring each monthly testing period.

In order to assess the health of the test organismsand laboratory performance, a concurrent referencetoxicant test was conducted for each of the test speciesduring each testing period. The reference toxicant testwas conducted using a dilution series of the toxicant inlaboratory control water. For a given test method,successive tests were performed with the same referencetoxicant, at the same concentrations, in the same dilutionwater, and using the same data analysis methods. Thetoxicity endpoints from the reference toxicant tests ofeach test method were subsequently plotted on a runningcontrol chart from the last 20 tests. The mean and upperand lower control limits (± 2 standard deviations) wererecalculated with each successive test result. The outliers,which were values falling outside the upper and lowercontrol limits, and trends of increasing or decreasingsensitivity, were readily identified. At the p= 0.05probability level, one in 20 tests (5%) would be expectedto fall outside of the control limits by chance alone.

The USEPA conducted toxicity tests concurrentwith the BES laboratory during the April 1998 samplingevent for the fathead minnow and daphnid test speciesand during the May 1998 sampling event for the alga.

The in situ toxicity test used a field testing protocolto evaluate the response of fathead minnow larvae todirect and continuous site-water exposure. Ten day-oldfathead minnow larvae were deployed in test chambers atSites B, D, F and at the Windmill Site (in situ testcontrol) on a single test. After seven days, the testchambers were recovered and evaluated in the field.Survival of the larvae was used as the endpoint to deter-mine potential impact during the 7-day exposure period.

During the February, March, and April samplingevents, definitive toxicity tests were performed with algaeusing Site B water. The methods used for the definitivealgae tests are described in detail in Short-term Methodsfor Estimating the Chronic Toxicity of Effluents andReceiving Water to Freshwater Organisms (USEPA,1994).

Water samples for chemical analysis were alsocollected during each toxicity testing sampling event.Samples for selenium and sulfate were analyzed by theUSBR. Other water chemistry (performed by BES)included temperature, dissolved oxygen (DO), pH,conductivity, salinity, ammonia, total chlorine, hardness,alkalinity, and total suspended solids. Samples were alsoanalyzed for DO, pH, conductivity and salinity in thefield. Water chemistry data measured in the laboratorycomparing each of the sites may be found in Figures 21–30. Tables 9–12 summarize the field chemistry data.

Except as noted above, specific sampling andtesting protocols for each procedure may be found in

63


Compliance Monitoring Program for Use and Operation ofthe Grassland Bypass Project (USBR et al., 1996) and theQuality Assurance Project Plan (Entrix, Inc., 1997).

ResultsThe results from the second year of the toxicity monitor-ing program are presented below. Toxicity testing, asdescribed in Compliance Monitoring Program for Use andOperation of the Grassland Bypass Project (USBR et al.,1996) began in October 1996. Data compared to 1996-97may be found in the first Annual Report (USBR, 1998).

Laboratory Toxicity Testing

There were twelve monthly laboratory toxicity screeningtest periods between October 1997 and September 1998using water collected from Sites B, C, D, and F with theDMC ambient control water. The USEPA Region IXlaboratory performed concurrent toxicity tests with theBES laboratory from split samples collected during theApril (fathead minnow and daphnid) and May 1998 (alga)sampling events. The USEPA split sample results arefound in Table 14. The results of these split sample testsare discussed below in each respective toxicity test section.Results for the definitive alga test may be found in Tables7 and 8, which are discussed under the alga test section.

Chronic 7 Day Fathead Minnow

(Pimephales promelas) Larval Survival

The fathead minnow toxicity test survival results arepresented in Table 3 and in Figures 5, 10, 15, and 20.Seven sampling events produced statistically significantly(p<0.05) reduced fathead minnow larval survival. Thereduced survival was observed during the October (SiteF), November (Site C), and December 1997 (Sites C andD; and January (Sites C and D), February (Sites C, D,and F), March (Sites C, D, and F), and June 1998 (SiteF) testing periods.

April 1998 split sample comparisons with theUSEPA Region IX laboratory showed similar results.However, no statistically significant (p<0.05) difference,as revealed in the USEPA data, was indicated for Site Fby the BES laboratory. The USEPA fathead minnowtoxicity test results are presented in Table 14.

Each concurrent P. promelas reference toxicantsurvival endpoint was within the control chart limits.

All data for the DMC ambient control and thelaboratory control met the 80% minimum survivalacceptability criterion as shown in Table 3.

The survival data for the fathead minnow larvaeindicate an adverse effect for Site C, Site D, and poten-tially Site F during the winter months. Site C exhibitedthe greatest effects, both in total number of occurrences(5 months) and in intensity (only 40% survival in January1998). This is in contrast to the first year of the studywhen no specific trends were observed for any site. Anunusually wet winter may have contributed to thiscondition. It should be noted that Sites C and F are outof the influence of Sites B. Site D is influenced by bothsite C and B water.

Chronic 7 Day Fathead Minnow

(Pimephales promelas) Larval Growth

The fathead minnow toxicity test growth results arepresented in Table 4 and in Figures 2, 7, 12, and 17.Statistically significant (p<0.05) reduced growth rateswere observed during the October (Sites B, C, D, and F),November (Sites B, C, and F), and December 1997 (SiteC), and January (Sites C and D), February (Sites C, D,and F), March (Sites C, D, and F), June (Site F), andAugust 1998 (Site C) testing periods.

April 1998 split sample comparisons with theUSEPA Region IX laboratory showed similar results.No statistical difference was indicated for Site C larvalfish growth by the BES laboratory even though theresponse for growth was similar to the USEPA data forthis site.

Each concurrent P. promelas reference toxicantgrowth endpoint was within the control chart limits.

All data for the DMC ambient control and thelaboratory control met the 0.25mg/surviving adultminimum growth acceptability criterion as shown inTable 14.

The growth data for the fathead minnow larvaeindicate an adverse effect for Site C, Site D, and poten-tially Site F during the winter months. Site C exhibitedthe greatest effects, both in total number of occurrences(7 months) and in intensity (52% reduction in growth ascompared to the DMC in January 1998). This is incontrast to the first year of the study when no specifictrends were observed for any site. The fish growth datafollow the same trends as the fish survivability data forwater year (WY) 1998. That is, there was significantlyreduced growth for fathead minnows tested with waterfrom Sites C and D and sometimes Site F during thewinter months, with the greatest effect seen in fish testedwith Site C water. Again, this was in contrast to the fishgrowth data for WY 1997 in which little effect wasobserved on fish growth at these sites.


64

Daphnia magna Short-Term Chronic

Survival

The D. magna toxicity test survival results are presentedin Table 1 and in Figures 4, 9, 14, and 19. None of thesampling events detected statistically significant (p<0.05)reduced survival of D. magna survival during any of thetesting events.

April 1998 split sample comparisons with theUSEPA Region IX laboratory indicated that the resultswere similar. Both laboratories indicated no statisticallysignificant results for any of the sites. However, it shouldbe noted that the USEPA laboratory made its compari-sons with the laboratory control water as ambient waterrather than the DMC water. The USEPA D. magnatoxicity test results are presented in Table 14.

Seven of the twelve concurrent D. magna referencetoxicant survival endpoints were within the control chartlimitations. The remaining five reference toxicant testsproduced nearly complete mortality in all exposureconcentrations and as a result did not meet the 80%control survival acceptability criterion.

The DMC ambient control data met the 80%minimum survival acceptability criterion in all but onetest period (February 1998). The laboratory control metthe survival acceptability criterion in four out of twelvetest periods, failing to reach the required levels in eightsampling events (November 1997; January, February,March, April, May, June, and July 1998) as shown inTable 1. An alternative organism source, procured inAugust 1998, appears to have remedied the laboratorycontrol survival problems.

No adverse effects or specific trends were noted onD. magna survival during the second year of the GBPstudy, which is similar to the results from the first year ofthe GBP.

Daphnia magna Short-Term Chronic

Reproduction

The D. magna toxicity test reproduction results arepresented in Table 2 and in Figures 1, 6, 11, and 16. Twosampling events detected statistically significant (p<0.05)reduced reproduction. The reduced reproduction wasobserved during the December 1997 (Site F) andJanuary 1998 (Sites B, D, and F) testing periods.

April 1998 split sample comparisons with theUSEPA Region IX laboratory results (Table 14) weresimilar. Neither the BES nor the USEPA laboratoriesreported adverse effects for any of the sites studied.

Only six of the concurrent D. magna referencetoxicant reproduction endpoints were within the controlchart limitations. The remaining six reference toxicanttests produced nearly complete mortality in all exposureconcentrations and as a result did not meet the meanreproduction (≥10 neonates/surviving female) acceptabil-ity criterion.

The DMC ambient control data met the ≥10neonates/surviving female minimum reproductionacceptability criterion in all but two test periods ( June1998 and July 1998). The laboratory control met thereproduction acceptability criterion in six of the twelve testperiods, failing to reach the required levels for six samplingevents ( January, February, March, April, June, and July1998) as shown in Table 2. As noted above in the D.magna survival studies, test organisms from an alternativesource were procured in August 1998. This seems to haveresolved the laboratory control reproduction problem.

No adverse effects or specific trends to the sitewaters were noted on D. magna reproduction during thesecond year of the GBP, which was similar to the resultsfrom the first year of the GBP.

Selenastrum capricornutum 96-Hour

Growth Test

The algal toxicity test growth results are presented inTable 5 and in Figures 3, 8, 13, and 18. Seven samplingevents produced statistically significant (p<0.05) reducedgrowth. These reduced growth rates were observedduring the October 1997 (Site B), and January (Site B),February (Site B), March (Site B), May (Sites B and F),June (Site B), and September 1998 (Sites B and D)testing periods.

The February, March, and April 1998 samplingevents included a definitive evaluation of Site B water todetermine the extent of algal growth reduction (Tables 7and 8). Site B water was diluted with laboratory controlwater for the February definitive test and with DMCambient water for the March and April definitive tests tocreate a concentration series of 6.25, 12.5, 25, 50, and100% Site B. The no observed effect concentrations(NOECs) for the definitive tests for these samplingevents were 50, 50, and 25% respectively for February,March, and April sampling events. For February, theNOEC was the same as the laboratory control water,while for March the 50% NOEC was the same as theDMC ambient control. In April the NOEC was lessthan the DMC ambient control water indicating asignificant reduction in algal growth.

65


May 1998 split sample comparisons with theUSEPA Region IX laboratory indicated similar results(Table 14). Both the USEPA and BES laboratoriesindicated reduced algae growth for Site B. The BESlaboratory showed a statistically significant (p<0.05)reduced growth response for Site F. The USEPAlaboratory response was reduced, but not low enough toproduce a statistically significant difference. Again,statistical comparisons with the USEPA laboratory weremade with the laboratory control water.

Each concurrent S. capricornutum referencetoxicant growth endpoint was within the control chartlimitations. However, the variability exceeded thesuggested 20% acceptability criterion in seven out of thetwelve tests. In addition, the reference toxicant controlfailed to meet the minimum algal cell density (≥ 1 x 106

cells/ml) on one occasion (August 1998).The laboratory exceeded the suggested 20%

acceptability criterion in four of twelve tests ( January,April, May, and September 1998). The laboratory controlfailed to meet the minimum algal cell density on twooccasions ( January and August 1998). The DMCambient control did not meet the density acceptabilitycriterion in four of the twelve tests (December 1997,January, February, and August 1998). The DMCambient control did not meet the variability criterion ineight of the twelve test periods. These results aresummarized in Table 5.

Overall, Site B had seven statistically significant(p<0.05) growth reductions when compared to the DMCambient control water. Site D and Site F each had onestatistically significant growth reduction. This is thesecond year that S. capricornutum tests have shown reducedgrowth in Site B water. However, based on definitivetoxicity testing for two of the three months in whichdefinitive testing with algae was completed, the NOECfor Site B was similar to the NOEC for the DMC water.

These data suggest that additional definitive testingshould be initiated to better evaluate the significance ofthe reduced algal growth in Site B test water. It is recom-mended that the Toxicity Steering Committee developtrigger points to determine the initiation for definitivetesting and the trigger for initiating a toxicity identifica-tion evaluation (TIE) based on definitive testing results.

In situ Toxicity Testing

One in situ toxicity testing event was conducted in May1998 using 10 day-old fathead minnow larvae. Fourstations were established at Sites B, D, F and the

Windmill Site (control). During these in situ tests,variations were made in the test apparatus from theprevious year. The fish cages were made more secureduring the exposure period so that there would beminimal change of the cage direction during the expo-sure period. This was accomplished by anchoring thecages to secure structures at each of the sites and byadding an additional anchor point (cinder block) to eachsample array. In addition, the fish were older than usedthe previous year: 10 days versus 4 days in 1997. Asshown in Table 6, the results were similar to the datacollected during the previous year, that is, there was anaccumulation of silt and small red worms in most of thetest chambers which probably caused either mortality ordisintegration of most of the test fish. Therefore, noconclusions could be drawn from the in situ study. The insitu studies as designed have been eliminated from thetoxicity program after concurrence with the DataCollection and Reporting Team.

No statistical difference (p<0.05) in survival wasdetected between the Windmill Site and the site watersduring the May 1998 testing period.

No conclusions may be drawn from the in situstudies at this time.

Water ChemistrySelenium

The selenium data are presented in Figure 21. Thehighest selenium concentrations (>100 mg/L) weredetected at Site B during the March, April, and May1998 sampling events. It is interesting to note that algalcell counts were significantly reduced in tests conductedduring these months. However, the October 1997 andFebruary and September 1998 sampling events had lowerselenium concentrations (58, 56, and 43 µg/L respec-tively), as well as reduced algae cell counts. Therefore, nospecific correlation can be made between algal cell countsand selenium concentrations at this time.

The selenium concentrations for each site weresimilar to those measured by the Central Valley RegionalWater Quality Control Board (see Chapter 4 of thisreport).

Sulfate

The sulfate results are presented in Figure 22. Sulfateconcentrations correlated with selenium concentrationsat the same site. Site B had the highest concentrations of


66

sulfate with peaks >1500 mg/L at Site B in October andNovember 1997, and January, March, April, May, andJune 1998. These elevated sulfate concentrations couldnot be correlated with increased toxicity in any of theorganisms studied.

Other Water Chemistry

The laboratory water chemistry data are presented inFigures 21–30. All analysis were performed at the BESLaboratory, except for selenium and sulfate. Tables 9–13provide water chemistry data collected in the field forconductivity, DO, pH, and temperature.

The conductivity was higher for Site B water.Site B water was also on average higher in DO, pH, andhardness, while these parameters were lowest in Site Fwater. Total suspended solids were generally higher inSite F water and lowest in Site B water. No trend inalkalinity was observed. The highest ammonia nitrogenconcentration was observed in September 1998 at Site F(4.27 mg/L). The highest total chlorine concentrationobserved was 0.5 mg/L, measured at various times inSite B, Site D, and Site F waters. No correlation betweenthe water chemistry data and the toxicity testing data isapparent.

ConclusionsA total of one hundred and forty-four laboratory toxicityscreening tests comparing the site waters (B, C, D, andF) with the ambient control (Delta Mendota Canal)were conducted between October 1997 and September1998 using three species short-term chronic tests. Ofthese tests, 44 endpoints of the 240 possible (18.3%)exhibited statistically significant (P<0.05) resultscompared to the ambient control tests (Site B = 10,Site C = 12, Site D = 10, and Site F = 12). This levelrepresents an increase from the previous year of 24significantly reduced endpoints (10%). The Daphniamagna was the least sensitive of the species testedaccounting for four of the significant responses usingboth survival and reproduction as the end point. Theseresponses were during December 1997 and January 1998(Site F = 2, Site D = 1, and Site B = 1).

For the second year the algae exposed to Site Bwater exhibited reduced growth when compared toDMC ambient control water in seven out of twelve

months. Definitive algal tests conducted for threeconsecutive months indicate that reduced algae growthis manifested at an average of 50% Site B water whencompared to DMC water. Additional definitive testingshould be conducted to evaluate the No ObservedEffect Concentration (NOEC) for Site B test water.Based on the outcome of the definitive results, a toxicityinvestigation evaluation (TIE) should be considered toidentify the possible chemicals causing the reduced algalgrowth.

The larval fathead minnow accounted for 29 of thesignificant responses using survival and growth as theendpoint. The majority of these responses were duringthe wet-weather months (October 1997 through March1998) at Site C, D, and F. BES was authorized toconduct a TIE for Site C water in April 1998 if surviv-ability was 50% or less for fathead minnows. The TIEmight have indicated the identity of possible chemicalscausing toxicity for Sites C and F. However, there was noreduced fish survivability in the site waters for theremainder of the year.



U.S. Bureau of Reclamation et al. 1996. ComplianceMonitoring Program for Use and Operation of theGrassland Bypass Project, September 1996. U.S.Bureau of Reclamation, Mid-Pacific Region,Sacramento, CA.

U.S. Bureau of Reclamation. 1998. Grassland BypassProject Annual Report. October 1, 1996 throughSeptember 30, 1997. U.S. Bureau of Reclamation,Mid-Pacific Region, Sacramento, CA.

U.S. Environmental Protection Agency. 1994. Short-term Methods for Estimating the Chronic Toxicityof Effluents and Receiving Water to FreshwaterOrganisms. EPA-600-4-91-002. July 1994, ThirdEdition. Office of Research and Development.

U.S. Environmental Protection Agency. 1987. A Short-term Chronic Toxicity Test Using Daphnia magna.EPA/600/D-87/080. March, 1987. Office ofResearch and Development.

67

Chapter 5: T

oxicity Studies

Figure 1

Site B Compared to Delta Mendota Canal—Chronic Endpoints

Figure 2


Daphnia magna Reproduction

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Fathead Minnow Growth

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Site B

Results statistically different from control

Laboratory Control

Minimum test acceptability for control

*

Grassland B

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68

Figure 3


Figure 4

Site B Compared to Delta Mendota Canal—Acute Endpoints


Site B


Laboratory Control


*

Selenastrum capricornutum Growth

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Daphnia magna Survival

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69

Chapter 5: T

oxicity Studies

Figure 5

Site B Compared to Delta Mendota Canal—Acute Endpoints

Fathead Minnow Survival

40

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100

Oct

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*

Grassland B

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70

Figure 6

Site C Compared to Delta Mendota Canal—Chronic Endpoints

Figure 7



0

10

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*

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Site B


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*

71

Chapter 5: T

oxicity Studies

Figure 8


Figure 9

Site C Compared to Delta Mendota Canal—Acute Endpoints


0102030405060708090

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Oct

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Grassland B

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72

Figure 10

Site C Compared to Delta Mendota Canal—Acute Endpoints


40

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73

Chapter 5: T

oxicity Studies

Figure 11

Site D Compared to Delta Mendota Canal—Chronic Endpoints

Figure 12



Site B


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*


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Grassland B

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74

Figure 13


Figure 14

Site D Compared to Delta Mendota Canal—Acute Endpoints


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75

Chapter 5: T

oxicity Studies

Figure 15

Site D Compared to Delta Mendota Canal—Acute Endpoints


Site B


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*


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Grassland B

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76

Figure 16

Site F Compared to Delta Mendota Canal—Chronic Endpoints

Figure 17



0

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77

Chapter 5: T

oxicity Studies

Figure 18


Figure 19

Site F Compared to Delta Mendota Canal—Acute Endpoints


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78

Figure 20

Site F Compared to Delta Mendota Canal—Acute Endpoints


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*

79


Figure 21

Selenium of Site Waters as Measured by USBR

Detection limit was 2 µg/L for all tests through May, 1998. Thereafter, detection limit was 0.40 µg/L

Figure 22

Sulfate of Site Waters as Measured by USBR

0

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80

Figure 23

Conductivity of Site Waters as Measured at BES Laboratory

Figure 24

Total Suspended Solids of Site Waters as Measured at BES Laboratory

0

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ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

17-F

eb-9

8

10-M

ar-9

8

7-A

pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

B

C

D

F

DMC

B

C

D

F

DMC

81


Figure 25Dissolved Oxygen of Site Waters as Measured at the BES Laboratory

Figure 26

pH of Site Waters as Measured at the BES Laboratory

4

6

8

10

12

14

16

Date

Dis

so

lve

d O

xy

ge

n (

mg

/L)

6.5

7.0

7.5

8.0

8.5

9.0

Date

pH

14-O

ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

17-F

eb-9

8

10-M

ar-9

8

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pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

14-O

ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

17-F

eb-9

8

10-M

ar-9

8

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pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

B

C

D

F

DMC

B

C

D

F

DMC


82

Figure 27Alkalinity of Site Waters as Measured at the BES Laboratory

* Measurement Not Available (NA) for Site B

Figure 28

Hardness of Site Waters as Measured at the BES Laboratory

0

50

100

150

200

250

300

350

Date

Alk

ali

nit

y (

mg

/L a

s C

aC

O3)

0

200

400

600

800

1,000

1,200

1,400

1,600

Date

Ha

rdn

ess (

mg

/L a

s C

aC

O3)

14-O

ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

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l-98

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ov-

97

2-D

ec-9

7

20-J

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17-F

eb-9

8

10-M

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pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

B

C

D

F

DMC

B

C

D

F

DMC

83


Figure 29

Ammonia of Site Waters as Measured at the BES Laboratory

Figure 30

Total Chlorine of Site Waters as Measured at the BES Laboratory

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Date

Am

mo

nia

(p

pm

as n

itro

gen

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Date

To

tal C

hlo

rin

e (

mg

/L)

14-O

ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

17-F

eb-9

8

10-M

ar-9

8

7-A

pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

14-O

ct-9

7

4-N

ov-

97

2-D

ec-9

7

20-J

an-9

8

17-F

eb-9

8

10-M

ar-9

8

7-A

pr-

98

12-M

ay-9

8

9-Ju

n-9

8

6-Ju

l-98

10-A

ug

-98

8-S

ep-9

8

B

C

D

F

DMC

B

C

D

F

DMC


84

Table 1. Daphnia magna Survival (Percent)

Site Location

Ambient Laboratory

Date B C D F (DMC) Control

Oct-97 80 90 100 90 100 90Nov-97 100 80 100 100 100 0Dec-97 100 100 90 80 100 80Jan-98 80 90 100 100 100 0Feb-98 80 80 100 90 50** 0Mar-98 100 90 100 100 100 0Apr-98 100 100 90 100 100 0May-98 100 100 90 100 100 40Jun-98 90 100 75 100 90 0Jul-98 70 90 100 90 90 70Aug-98 100 100 100 90 90 100Sep-98 80 100 90 100 80 100

* Statistically significant event (P<0.05). Statistics were computed between all site means and the DMC ambient watersample.

No statistics were computed between sampling dates.** DMC water failed to meet the survival (> 80%) acceptability criteria.

Site Location

Ambient Laboratory


Oct-97 42.2 + 9.7 37.9 + 11.2 41.7 + 3.3 34.8 + 13.5 34.9 + 8.5 32.0 + 10.4Nov-97 37.3 + 2.7 28.6 + 5.1 34.0 + 3.6 30.3 + 3.9 22.0 + 10.2 21.5 + 9.4Dec-97 46.0 + 11.9 44.5 + 3.9 41.2 + 12.7 32.7 + 12.4* 43.6 + 9.2 21.1 + 11.0Jan-98 13.7 + 6.4* 21.8 + 11.3 18.5 + 8.1* 14.5 + 4.4* 27.4 + 10.6 0Feb-98 67.0 + 8.5 70.5 + 13.4 69.9 + 5.4 61.3 + 23.5 39.3 + 22.9** 0Mar-98 32.0 + 9.6 28.9 + 13.5 28.0 + 6.4 29.1 + 6.4 28.5 + 11.9 0Apr-98 18.7 + 8.1 25.2 + 7.0 19.6 + 7.5 20.2 + 4.9 10.2 + 2.3 0May-98 34.9 + 6.6 34.6 + 6.3 31.6 + 13.5 21.1 + 4.8 20.1 + 2.2 18.4 + 4.8Jun-98 30.8 + 17.1 5.70 + 18.0 7.88 + 17.3 2.30 + 7.3 9.00 + 10.7*** 0Jul-98 10.8 + 6.6 11.9 + 5.2 12.6 + 5.3 8.20 + 3.0 6.60 + 3.5*** 5.90 + 4.3Aug-98 57.5 + 25.6 71.3 + 34.0 49.1 + 27.4 29.9 + 22.9 32.7 + 24.1 28.2 + 11.5Sep-98 46.4 + 18.7 56.2 + 5.9 50.7 + 10.6 45.8 + 12.6 40.5 + 16.7 50.2 + 11.7


No statistics were computed between sampling dates.** DMC water failed to meet the survival (> 80%) acceptability criteria.***DMC water failed to meet the reproduction (> 10%) acceptability criteria.

Table 2. Daphnia magna Mean Reproduction

(Number of Neonates per Female + Standard Deviation)

85


Table 3. Pimephales promelas (Fathead Minnow)

Larval Survival (Percent + Standard Deviation)

Site Location

Ambient Laboratory


Oct-97 88 + 5.0 88 + 9.6 85 + 12.9 60 + 8.2* 95 + 10.0 98 + 5.0Nov-97 85 +19.1 75 + 19.1* 88 + 9.6 88 + 9.6 98 + 5.0 98 + 5.0Dec-97 90 + 8.2 50 + 21.6* 58 + 15.0* 83 + 20.6 88 + 15.0 85 + 12.9Jan-98 100 + 0 40 + 18.3* 50 + 18.3* 90 + 0.08 90 + 14.1 95 + 5.8Feb-98 93 + 5.0 43 + 17.1* 73 + 15.0* 80 + 8.2* 93 + 9.6 93 + 9.6Mar-98 95 + 5.8 60 + 18.3* 68 + 26.3* 53 + 9.6* 95 + 10.0 84 + 21.1Apr-98 100 + 0 95 + 5.8 95 + 5.8 100 + 0 85 + 19.1 100 + 0May-98 100 + 0 98 + 5.0 98 + 5.0 58 + 26.3 81 + 27.1 100 + 0Jun-98 88 + 15.0 98 + 5.0 98 + 5.0 65 + 12.9* 98 + 5.0 95 + 5.8Jul-98 98 + 5.0 93 + 5.0 100 + 0 78 + 26.3 93 + 9.6 100 + 0Aug-98 88 + 5.0 100 + 0 95 + 5.8 95 + 5.8 95 + 5.8 100 + 0Sep-98 98 + 5.0 93 + 9.6 100 + 0 100 + 0 100 + 0 100 + 0


No statistics were computed between sampling dates.

Site Location

Ambient Laboratory


Oct-97 0.48 + 0.06* 0.44 + 0.06* 0.40 + 0.14* 0.34 + 0.08 0.58 + 0.08 0.50 + 0.05Nov-97 0.55 + 0.17* 0.57 + 0.13* 0.72 + 0.11 0.65 + 0.02 0.76 + 0.11 0.71 + 0.11Dec-97 0.60 + 0.07 0.38 + 0.21* 0.52 + 0.07 0.63 + 0.10 0.63 + 0.08 0.57 + 0.05Jan-98 0.65 + 0.04 0.26 + 0.14* 0.30 + 0.14* 0.58 + 0.10 0.54 + 0.10 0.57 + 0.07Feb-98 0.74 + 0.03 0.35 + 0.15* 0.53 + 0.09* 0.56 + 0.10 0.70 + 0.06 0.59 + 0.14Mar-98 0.67 + 0.05 0.31 + 0.13* 0.39 + 0.17* 0.30 + 0.07 0.54 + 0.08 0.53 + 0.08Apr-98 0.67 + 0.05 0.53 + 0.04 0.59 + 0.04 0.58 + 0.08 0.47 + 0.09 0.54 + 0.09May-98 0.62 + 0.05 0.50 + 0.06 0.54 + 0.02 0.32 + 0.12 0.41 + 0.10 0.51 + 0.01Jun-98 0.64+0.05 0.56+0.03 0.59+0.06* 0.38+0.09 0.57+0.05 0.64+0.02Jul-98 0.69 + 0.09 0.52 + 0.08 0.68 + 0.09 0.45 + 0.19 0.53 + 0.04 0.68 + 0.04Aug-98 0.65 + 0.03 0.59 + 0.03* 0.64 + 0.06 0.65 + 0.03 0.65 + 0.03 0.63 + 0.06Sep-98 0.57 + 0.03 0.56 + 0.06 0.60 + 0.05 0.51 + 0.04 0.53 + 0.03 0.66 + 0.03


No statistics were computed between sampling dates.

Table 4. Pimephales promelas (Fathead Minnow) Mean Growth

(in Milligrams + Standard Deviation)


86

5/12/98 5/19/98 Percent Survival

No. No. Found No. Found No. Alive/ No. Alive/

Sample ID Deployed Dead Alive No. Depolyed No. Total Bodies

Windmill Site 80 5 24 30.0 82.8Site B 80 3 23 28.8 88.5Site D 80 2 21 26.3 91.3Site F 80 1 21 26.3 95.5

Very light silt accumulation occurred in the Windmill Site cages. Heavy to moderate silt accumulation occurredin the Site B, Site D, and Site F cages.Some small red worms were found in the Site B, Site D, and Site F cages. Little or no red worms were found inthe Windmill Site cages. Worm presence seems to correlate with silt accumulation.

Table 6. BES In Situ Toxicity Study:

Pimephales promelas (Fathead Minnow) Larval Survival

Site Location

Date Var. Var. Var. Var. Ambient Var. Lab Var.

B (%) C (%) D (%) F (%) (DMC) (%) Control (%)

Oct-97 3.0* 15.1 42.3 19.2 47.4 13.1 43.9 15.8 50.4 13.4 50.3 10.9Nov-97 23.8 31.1 19.6 22.9 23.8 21.4 29.0 35.7 15.8 24.8 31.3 3.6Dec-97 14.8 44.8 14.2 35.3 24.2 6.0 19.2 15.4 6.25** 47.0 25.0 11.1Jan-98 1.04* 64.4 11.9 35.3 14.5 22.1 6.83 27.8 9.1** 25.3 9.14 20.7Feb-98 4.21* 26.5 7.93 37.2 10.9 23.3 11.8 47.7 8.33** 34.7 17.1 15.6Mar-98 5.42* 8.9 20.3 10.7 16.8 22.5 16.5 49.3 13.4 46.2 25.5 14.3Apr-98 19.0 27.3 36.1 36.6 25.8 34.5 34.8 23.1 23.7 18.2 32.5 26.3May-98 8.71* 9.6 26.6 38.9 17.8 23.0 9.92* 55.7 22.2 32.8 19.3 21.5Jun-98 15.8* 15.6 25.4 21.0 21.3 16.3 20.1 34.2 22.7 8.8 32.1 11.8Jul-98 23.4 19.6 20.5 34.1 23.7 25.8 23.2 18.0 22.2 26.3 27.6 4.2Aug-98 5.55 13.3 6.41 17.0 6.00 35.4 7.54 11.0 4.16** 22.4 7.45 16.2Sep-98 21.6* 7.2 27.4 14.3 27.7* 6.0 29.8 20.7 32.3 13.6 28.0 22.6


No statistics were computed between sampling dates.** DMC water failed to meet the survival (> 80%) acceptability criteria.

Table 5. Selenastrum capricornutum Cell Counts (cells/mL) with Variance (%)

Cell Count Values Expressed as the Exponent 105 (Selenate Added)

87


96 hour Growth

February 1998* Mar-98 Apr-98

Sample ID Count (cells/mL) Variance (%) Count (cells/mL)Variance (%) Count (cells/mL)Variance (%)

Ambient Control 8.33 x 105 34.7 1.34 x 106 46.2 2.37 x 106 18.2Lab Control 1.41 x 106 28.2 NA NA NA NA6.25% 1.72 x 106 21.1 1.89 x 106 28.9 1.67 x 106 36.512.5 1.29 x 106 25.5 1.44 x 106 13.2 2.38 x 106 14.525 1.05 x 106 47.8 1.77 x 106 29.4 1.83 x 106 33.950 1.04 x 106 33.6 1.36 x 106 26 1.38 x 106 21.3100 4.21 x 105 26.5 5.42 x 105 8.9 1.90 x 106 27.3

*The 2/98 sample dilutions were made with lab control water.NA—Not applicable

Table 7. Definitive Site B Selenastrum capricornutum Results

Test Month IC 50 IC 25 NOEC LOEC Toxic Units

2/98 (v. Ambient) 79.157 46.854 >100 >100 <12/98 (v. Lab) 65.498 18.587 50 100 2Mar-98 83.621 58.826 50 100 2Apr-98 >100 31.672 25 50 4

Data Analysis—All toxicity testing results were analyzed using EcoAnalysis, Inc. software program TOXIS (Version 2.5). Thisprogram determines if there is a statistically significant reduction in response at the p = 0.05 level and utilizes the flowchartfor statistical analysis outlined in EPA/600/4-91/002. The parameters of interest for the definitive tests are the No ObservedEffect Concentration (NOEC), the Lowest Observed Effect Concentration (LOEC), the resultant Toxic Units (TU) as well as the(25 and 50%) Inhibition Concentrations (IC). The IC values will show the point estimate of the sample concentration thatcauses a given percent reduction.

Table 8. Statistical Analysis of Growth Endpoint


88

Table 9. Conductivity (µS) of Site Waters Measured in the Field

Site Location

B C D F Windmill Site Ambient

Month Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7

Oct-97 3990 NT 909 NT 1590 NT 1034 NT NT NT 361 NTNov-97 5080 NT 1439 NT 2440 NT 1526 NT NT NT 640 NTDec-97 4140 NT 1236 NT 1710 NT 1678 NT NT NT 474 NTJan-98 4140 NT 945 NT 1108 NT 2000 NT NT NT 604 NTFeb-98 2870 NT 722 NT 1071 NT 1686 NT NT NT 437 NTMar-98 4980 NT 1142 NT 1865 NT 1725 NT NT NT 500 NTApr-98 4570 NT 1944 NT 3180 NT 1866 NT NT NT 373 NTMay-98 5680 5400 2350 NT 5680 4170 1210 1572 1751 1413 256 NTJun-98 4850 NT 1270 NT 3770 NT 863 NT NT NT 219 NTJul-98 5030 NT 910 NT 3190 NT 940 NT NT NT 287 NTAug-98 2860 NT 1969 NT 3240 NT 548 NT NT NT 337 NTSep-98 4130 NT 491 NT 2730 NT 829 NT NT NT 367 NT

NT = Not TestedNA = Not Available

Table 10. Dissolved Oxygen (in mg/L) of Site Waters Measured in the Field

Site Location



Oct-97 13.1 NT 6.1 NT 7.1 NT 7.9 NT NT NT 8.9 NTNov-97 13.4 NT 6.8 NT 7.8 NT 8.2 NT NT NT 9.5 NTDec-97 11.4 NT 8.1 NT 8.4 NT 7.8 NT NT NT 9.3 NTJan-98 10.0 NT 7.8 NT 7.9 NT 7.5 NT NT NT 8.3 NTFeb-98 10.7 NT 9.3 NT 9.2 NT 7.6 NT NT NT 9.5 NTMar-98 10.1 NT 9.3 NT 9.2 NT 7.9 NT NT NT 9.6 NTApr-98 10.2 NT 8.1 NT 9.1 NT 7.0 NT NT NT 9.4 NTMay-98 11.8 10.0 9.7 NT 10.9 10.2 8.3 9.2 6.2 8.6 8.8 NTJun-98 10.8 NT 7.3 NT 9.5 NT 7.5 NT NT NT 9.4 NTJul-98 9.7 NT 6.9 NT 8.8 NT 5.6 NT NT NT 8.9 NTAug-98 7.6 NT 7.9 NT 8.0 NT 8.0 NT NT NT 6.9 NTSep-98 11.0 NT 9.1 NT 9.2 NT 3.6 NT NT NT 10.2 NT


Site Location



Oct-97 8.4 NT 8.3 NT 8.4 NT 8.3 NT NT NT 8.7 NTNov-97 8.7 NT 8.4 NT 8.4 NT 8.4 NT NT NT 8.4 NTDec-97 8.2 NT 8.2 NT 7.9 NT 8.2 NT NT NT 8.7 NTJan-98 8.1 NT 8.0 NT 8.3 NT 8.1 NT NT NT 8.0 NTFeb-98 8.1 NT 8.5 NT 8.5 NT 8.4 NT NT NT 8.6 NTMar-98 8.1 NT 8.8 NT 8.4 NT 7.8 NT NT NT 8.8 NTApr-98 8.1 NT 8.0 NT 8.0 NT 7.7 NT NT NT 7.7 NTMay-98 8.4 8.0 8.1 NT 8.2 8.0 7.9 7.9 7.8 7.5 7.7 NTJun-98 NA NT NA NT NA NT NA NT NT NT NA NTJul-98 8.2 NT 7.8 NT 8.2 NT 7.1 NT NT NT 7.1 NTAug-98 8.6 NT 8.5 NT 8.5 NT 7.8 NT NT NT 7.0 NTSep-98 8.7 NT 8.4 NT 8.7 NT 8.1 NT NT NT 8.1 NT

Table 11. pH of Site Waters Measured in the Field


89


Site Location



Oct-97 7.0 NT 3.0 NT 4.0 NT 5.0 NT NT NT 12 NTNov-97 NA NT NA NT NA NT NA NT NT NT NA NTDec-97 6.5 NT 8.0 NT 8.0 NT 5.0 NT NT NT 17 NTJan-98 6.5 NT 7.0 NT 7.0 NT 6.0 NT NT NT 15 NTFeb-98 8.0 NT 5.0 NT 11 NT 3.0 NT NT NT 12 NTMar-98 7.5 NT 2.0 NT 10 NT 6.0 NT NT NT 15 NTApr-98 7.8 NT 7.0 NT 10 NT 3.5 NT NT NT 26 NTMay-98 6.8 NA 3.0 NT 6.0 NA 4.5 NA 3.5 NA 16 NTJun-98 7.5 NT 4.5 NT 6.0 NT 3.0 NT NT NT 15 NTJul-98 7.2 NT 3.0 NT 5.0 NT 3.5 NT NT NT NA NTAug-98 7.0 NT 4.0 NT 5.8 NT 5.5 NT NT NT 16.6 NTSep-98 6.9 NT 3.5 NT 5.5 NT 4.0 NT NT NT 15 NT


Table 13. Depth of Sample Point (in feet)

Table 12. Temperature (deg. Celsius) of Site Waters Measured in the Field

Site Location

Month B C D F Windmill Site Ambient

Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7 Day 1 Day 7

Oct-97 17.5 NT 17.6 NT 17.3 NT 16.2 NT NT NT 17.1 NTNov-97 19.8 NT 19.8 NT 19.8 NT 18.5 NT NT NT 18.8 NTDec-97 11.8 NT 11.0 NT 11.0 NT 11.0 NT NT NT 12.8 NTJan-98 12.7 NT 12.1 NT 11.3 NT 12.2 NT NT NT 13.1 NTFeb-98 12.3 NT 11.8 NT 12.5 NT 11.6 NT NT NT 13.2 NTMar-98 14.8 NT 15.0 NT 14.5 NT 14.0 NT NT NT 16.8 NTApr-98 15.5 NT 14.7 NT 14.5 NT 15.0 NT NT NT 14.6 NTMay-98 15.7 19.5 15.6 NT 16.2 19.6 15.5 19.5 16.0 22.5 16.2 NTJun-98 21.2 NT 22.7 NT 21.9 NT 20.7 NT NT NT 21.7 NTJul-98 25.0 NT 25.1 NT 25.3 NT 24.2 NT NT NT 25.0 NTAug-98 26.0 NT 25.0 NT 25.5 NT 24.7 NT NT NT 24.0 NTSep-98 28.0 NT 27.2 NT 27.5 NT 27.0 NT NT NT 25.0 NT


Laboratory

Organism Test Site B Site C Site D Site F DMC Control

Fathead minnow 7day % survival 100% 98% 95% 80 %* 100% 100%Fathead minnow 7 day growth (mg/fish) 0.95 0.74* 0.89 0.78 0.83 0.84Daphnia magna 7day % survival 80% 100% 100% 90% 100% 100%Daphnia magna 7 day growth (mg/fish) 44.1 46.3 60.7 53.6 47.7 32.9Selenastrum capriconatum** Growth (10^5 cells/mL) 25.98 33.45 32.95 30.88 36.58 38.72

* Statistically significant** Data is from test conducted in May 1998.Source: U.S. EPA Region IX Laboratory, Grasslands Bypass Project Toxicty Testing Report. April and May 1998

Table 14. U.S. EPA Toxicity Testing Data Summary—April/May, 1998


90

91

Chapter 6: Biological Effects

Chapter 6

Biological Effects ofthe Reopening of the

San Luis Drain toCarry Subsurface

Irrigation Drainwater

William N. Beckon*, Mary Dunne†, John D. Henderson*, Joseph P.Skorupa*, Steven E. Schwarzbach*, and Thomas C. Maurer

*U.S. Fish and Wildlife Service, Division of Environmental Contaminants†California Department of Fish and Game, Central Valley/Bay-Delta Branch


92

AbstractIn the second year of operation of the Grassland BypassProject (GBP), the biological effects of contaminantsimproved in some geographic areas and taxa but wors-ened in others. In Mud Slough below the San LuisDrain (SLD) outfall, selenium concentrations in fishtrended downward (still at levels of concern), whileselenium concentrations rose in some macroinvertebrates(waterboatmen). The release of drainwater into thewetlands channels feeding Salt Slough evidently wassufficiently prolonged (February 3–28, 1998) to adverselyaffect contaminant concentrations in the Salt Sloughecosystem, temporarily reversing the improvement thatoccurred during the first year of the GBP. An assessmentof selenium hazard to the aquatic ecosystems (Lemlyindex) in the Mud and Salt Slough areas indicates thatthe ecosystem hazard became more severe in both areas.This assessment is strongly influenced by transientmaxima in water and sediment concentrations. Improve-ments continue to be seen with respect to selenium levelsin both fish and invertebrates from the San JoaquinRiver sites. Continued biological monitoring is needed todistinguish long term trends from the temporary effectsof an unusually wet winter and spring in the second yearof the GBP.

IntroductionProject History

In 1985 the SLD was closed due to deaths and develop-mental abnormalities of waterbirds at a reservoir in theKesterson National Wildlife Refuge at the terminus ofthe SLD. The SLD, constructed by the U.S. Bureau ofReclamation (USBR), had been conceived as the solutionto valley-wide problems of disposal of agriculturaldrainwater. However, due to environmental concerns andbudget constraints, the SLD had never been completedas originally planned. The constructed portion of theSLD had been used only to convey subsurface agricul-tural drainwater from the Westland Water District in thewestern San Joaquin Valley. Farms in the adjacentGrassland area never used the SLD, but discharged toxicsubsurface drainwater through wetland channels in theSan Luis National Wildlife Refuge Complex and theChina Island Unit of the North Grasslands WildlifeArea (Refuges) to the San Joaquin River. This drainwatercontains extraordinarily elevated concentrations ofselenium, boron, chromium, and molybdenum, andextremely high concentrations of various salts that

disrupt the normal ionic balance of the aquatic system. Inaddition, unknown concentrations of agriculturalchemical residues (fertilizers and pesticides) maycontaminate this drainwater.

Discharge from Grassland area farms was unaf-fected by the closure of the SLD, and drainage continuedto contaminate Refuge water delivery channels after theclosure of Kesterson Reservoir. To address this problem, aproposal to reopen the SLD and extend it to MudSlough, a natural waterway in the Refuges, was imple-mented by the USBR in September 1996 with supportfrom other federal and state agencies (USBR, 1995;USBR and SL&D-MWA 1995; USBR et al., 1995).This project, known as the Grassland Bypass Project(GBP), diverts agricultural drainwater from Grasslandarea farms into the lower 28 miles of the SLD and thenceinto the lower portion of Mud Slough (about six miles).The GBP is intended to remove drainwater from morethan 90 miles of wetland water supply channels, includ-ing Salt Slough, and allow the Refuges full use of waterrights to create and restore wetlands on the Refuges. TheGBP, as currently implemented, is expected to continue,and even increase, the degradation of the northernmostsix miles of Mud Slough and the San Joaquin River untilphased-in load reduction goals can be achieved by waterdistricts. An essential component of the GBP is amonitoring program that tracks contaminant levels andeffects in water, sediment, and biota to ensure that theoverall effect of the GBP is not a net deterioration of theecosystems in the area affected by the GBP.

Contaminants of Concern

In the aftermath of the deaths and developmentalabnormalities of birds at Kesterson Reservoir in the early1980s, studies definitively traced the cause to selenium inthe agricultural subsurface drainwater in the reservoir(Suter, 1993). Because of this, and because of the well-known history of death, teratogenesis, and reproductiveimpairment caused by selenium in agriculturaldrainwater elsewhere (reviewed in Skorupa, 1998), theprimary contaminant of concern in this monitoringprogram is selenium. However, also of potential toxico-logical interest are nearly a dozen other inorganicconstituents in drainage water, especially boron.

Selenium

A set of ecological risk guidelines (Engberg et al., 1998)has been developed that provides benchmarks forinterpreting selenium concentrations in various biologi-

93


cally relevant matrices sampled in this study (Table 1).These guidelines are based on a large number of labora-tory studies and confirmatory field studies, most ofwhich are summarized in Skorupa et al. (1996) andLemly (1993). For water, sediment, and various bioticcompartments, the guidelines identify ranges of seleniumconcentrations associated with no known risk, uncertainrisk but of concern, and known toxicity.

The National Irrigation Water Quality Program(NIWQP), a U.S. Department of Interior program thatincludes the U.S. Fish and Wildlife Service (USFWS),the USBR, and the U.S. Geological Survey (USGS),recently reviewed the literature on selenium effects(NIWQP, 1998). This review suggests that some of thethresholds in Table 1 may need to be lowered to reflectnew information on the adverse effects of selenium onfish and wildlife. These interpretive guidelines are notregulatory standards. They represent a consensus ofindependent scientific reviewers regarding the ecologicaland toxicological relevance of selenium residues.

Boron

The toxic effects of boron on the wildlife taxa sampled inthis study are not yet sufficiently known to provide a setof ecological risk guidelines such as have been developedfor selenium effects.

MethodsThe role of the California Department of Fish andGame (CDFG) and the USFWS in this interagencyprogram is to execute the biomonitoring portion of the

Compliance Monitoring Program. The methods used bythe CDFG and USFWS are described in the QualityAssurance Project Plan for Use and Operation GrasslandBypass Project (QAPP; Entrix, Inc., 1997). Thesemethods are also based on standard operating proceduresdescribed in Standard Operation Procedures for Environ-mental Contaminant Operations (USFWS, 1995) andstandards used by the other agencies participating in thecompliance monitoring program. Deviations from theQAPP that have occurred since 1996 will be discussedlater in this section.

To obtain baseline data for this Project, theUSFWS began sampling in March 1992, after the reuseof the SLD was initially proposed by the USBR in 1991.The CDFG began sampling in August of 1993. USFWSand CDFG sampling plans before the reopening of theSLD and the early drafts of the monitoring plan weremutually influencing. Therefore, methods used by bothagencies before the final approval of the QAPP are,except a few minor differences, identical to the methodsultimately approved by the Data Collection and Report-ing Team. The sampling schedule, though, as discussedbelow, now follows a regular timetable.

Matrices Sampled

Samples of the biota were collected at each site andanalyzed for selenium and boron. Aquatic specimenswere collected with hand nets, seine nets and byelectrofishing. Mosquitofish (Gambusia affinis), inlandsilversides (Menidia beryllina), red shiners (Cyprinellalutrensis), fathead minnows (Pimephales promelas), carp(Cyprinus carpio), white catfish (Ameiurus catus), and

Matrix Units No Effect Level of Concern Toxicity

Threshold

Fish (whole-body) mg/kg (dry weight) < 4 4–12 > 12Vegetation (as diet) mg/kg (dry weight) < 2 3–7 > 7Animal food chain (invertebrates) mg/kg (dry weight) < 3 3–7 > 7Sediment mg/kg (dry weight) < 2 2–4 > 4Water (total recoverable Se) µg/L < 2 2–5 > 5Avian Egg (pop. hatchability) mg/kg (dry weight) < 3 3–8 > 8

Notes• These guidelines are intended to be population based. Thus, trends in means over time should be evaluated.• A tiered approach is suggested with water being the least meaningful measure and whole-body fish being the most

meaningful in assessment of ecological risk in a flowing system.• The toxic effect is reproductive impairment in fish and birds.• The whole-body (WB) fish guideline is for warm water fish.• The animal food chain guideline refers to hazards to birds. If food chain residues exceed 6 mg/kg then avian eggs should

be monitored.• Vegetation as diet is based on poultry literature.

Table 1. Recommended Ecological Risk Guidelines Based Upon Selenium Residues


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green sunfish (Lepomis cyanellus) were the principalspecies of fish collected. Waterboatmen (family:Corixidae), backswimmers (family: Notonectidae), and redcrayfish (Procambarus clarkii) were the principal inverte-brates collected. Separation of biological samples fromunwanted material also collected in the nets was accom-plished by using stainless steel or teflon sieves, and glass(or enamel) pans pre-rinsed with deionized water thennative water. To the extent possible, three replicate,composite samples (minimum 5 individuals totaling atleast 2 grams for each composite) of each primary specieslisted above were collected, but other species were alsocollected. Composite samples of skin-less muscle (fillets)from the larger gamefish species were submitted foranalysis; smaller forage fish and medium-size fish specieswere analyzed as composite whole-body samples exceptas noted below. Estimates of a conversion factor forrelating selenium concentration in skeletal muscle (M) towhole-body concentrations (WB) range from M=0.6WBfor many freshwater fish (Lemly and Smith, 1987) toM=0.045+1.23M for bluegills and M=-0.39+1.32WB forlargemouth bass (Saiki et al., 1991). Selenium concentra-tions discussed in text and displayed in figures below areaverages of composite sample concentrations except forbird eggs and except where otherwise stated.

The seed heads of wetland plants that provide foodfor waterfowl were collected in the late summer of 1996,1997, and 1998. Waterfowl and/or shorebird eggs,depending on availability, were collected from areasadjacent to Mud Slough and the SLD in the spring of1996, 1997, and 1998. In addition, in 1992 snowy egretand black-crowned night heron eggs were collected atEast Big Lake, which has served as a reference samplingsite for the USFWS. Bird eggs were analyzed individu-ally, and the results are discussed and displayed below asindividual concentrations and geometric means.

Graphs of whole-body and avian egg seleniumconcentrations presented in this report include indica-tions of the threshold concentrations delimiting the riskranges listed above (Table 1). The threshold between theNo Effect Zone and the Level of Concern Zone isindicated by a horizontal line of short dashes; theToxicity Threshold is marked on each graph by ahorizontal line of long dashes.

All biota samples were kept on ice while in thefield then kept frozen to 0°C during storage and ship-ment. For all samples, after freeze drying, homogeniza-tion, and nitric-perchloric digestion, total selenium wasdetermined by hydride generation atomic absorption

spectrophotometry and boron was determined byinductively coupled (argon) plasma spectroscopy.

Sampling Sites

Between 1992 and 1998 biological samples have beencollected from two sites on Salt Slough, five sites onMud Slough, two sites in the SLD, two sites on the SanJoaquin River, and one reference site that does notreceive selenium-contaminated drainwater. Beginning in1995, sampling efforts were concentrated on the sevensites identified in the Compliance Monitoring Plan: foursites on Mud Slough (C, D, E, and I), one on SaltSlough (F) and two San Joaquin River sites (G and H;Figure 1). Site C is located upstream of where theGrassland Bypass discharges into Mud Slough. Site D islocated immediately downstream of the discharge point.Site I is a small, seasonally flooded backwater area fed byMud Slough and is located approximately 1 miledownstream from Site D. Site E is located furtherdownstream where Mud Slough crosses State Highway140. To assess the mitigative effects of drainwaterremoval from Salt Slough one sample point, Site F, islocated on the San Luis National Wildlife Refugeapproximately 2 miles upstream of where State Highway165 crosses Salt Slough. Site G is located on the SanJoaquin River at Fremont Ford, upstream of the MudSlough confluence, while Site H is located on the SanJoaquin River 200 meters upstream of the Merced Riverconfluence, downstream of the Mud Slough confluence.Sites C, D, F, and I are monitored by the USFWS whileCDFG monitors Sites E, G, and H.

Sampling Times

Baseline sampling conducted by the USFWS occurredmonthly during the spring and summer of 1992 and thenbecame irregular during 1993 and 1994. Baselinesampling by CDFG occurred during the summer and fallof 1993 and then resumed in the spring of 1996. Be-tween 1992 and 1995 sampling by either the CDFG andthe USFWS occurred at least once every season. Experi-ence and interagency discussions led to the identificationof four sampling times based on historic water use anddrainage practices and on seasonal use of wetlandresources by fish and wildlife. Biota sampling since 1995has been synchronized quarterly during the months ofNovember, March, June, and August. Since 1996, avianeggs have been collected in May and June.

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Figure 1. Grassland Bypass Project Biota Monitoring Sites


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Deviations from the ComplianceMonitoring Plan and QualityAssurance Project Plan

In Appendix A, Section 7 of the QAPP, the use ofexternal quality assurance samples is discussed. Thisquality assurance technique was not employed by theCDFG or the USFWS on any samples submitted foranalysis before January of 1998.

In Appendix A, Section 4.7.3 teflon instrumentsare indicated for sample processing. The USFWS usedstainless steel instruments for all applications.

In Appendix A, Section 4.5 minimum numbers ofindividuals and material mass per sample are discussed.A number of composite samples analyzed since 1992have consisted of less than the minimum number ofindividuals and/or mass.

In Appendix A, Section 6.1 egg samples collectedin 1996 and 1997 as part of the GBP and reported in theresults section of this report were analyzed at TraceElement Research Laboratory (TERL) at Texas A & MUniversity, a USFWS contract laboratory. All biotasamples collected in 1998 were analyzed at TERL.TERL is subject to the same performance standards asEnvironmental Trace Substance Laboratory, therefore,the quality assurance objectives in Table 1 apply toanalytical results from TERL.

In Appendix A, Section 4.6 of the QAPP, seine netmesh size was increased from 3/16" to 1/4" after the firsttwo pre-Project collections 1993 from sampling Sites E,G, and H. This change in sampling gear resulted insignificant declines in catch abundance of smaller foragefish without altering diversity of representative assem-blages. Data collected from 1993 sampling efforts atthese sites were not included in making quantitativespatial or temporal comparisons between sites unlessotherwise noted.

ResultsMud Slough Near SLD Outfall(Sites C, D, and I)

Fish (Whole-Body)

During the second year of operation of the GBP, sele-nium concentrations in fish just above and below the SLDoutfall were generally lower than in the previous year(Figures 2–7). Above the SLD outfall (Site C) the averageselenium concentration in fathead minnows exceeded theLevel of Concern Threshold (see Table 1) in November1997, but averages for that species and other small fishdropped to No-Effect Levels during the remainder ofWater Year 1998 (WY; Figure 2). Below the SLD outfall(Sites D and I) mean selenium concentrations in fish

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mosquitofish silverside fathead minnow red shiner

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Figure 2. Selenium in Small Fish in Mud Slough Above the San Luis Drain Discharge (Site C).

Each bar represents an average of composite samples, the line of long dash marks theToxicity Threshold, and the line of short dash marks the Level of Concern Threshold (Table 1)

in this and subseqent graphs.

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remained at or very near levels of concern (4–12 mg/kgdry weight) throughout the second year of operation ofthe GBP (Figures 4–7). Nevertheless, the mean ofcomposite selenium concentrations for all fish from SitesD and I in the second year of the GBP (6.4 mg/kg, n=33)was significantly less than the mean for the first year(16.4 mg/kg, n=51; p<0.01, Student’s 2-tail t-test).

In June 1998 the splittail, a species federally listed asthreatened, was found in Mud and Salt sloughs for thefirst time since the current monitoring effort began in1992. One composite sample of splittails from each ofSites C, D, I, and F was analyzed. Selenium concentrationsin splittails were at levels of concern at all Mud Sloughsites and were highest (composite=7.1 mg/kg, 7 individu-als) at Site D, just below the SLD outfall (Figures 3, 5, 7,8, and 17). The selenium concentration in splittails at SiteC (composite=4.95 mg/kg, 4 individuals) was higher thanthe composite concentrations in other species sampled atthe same time at that site (mosquitofish 2.42 mg/kg, 30individuals; red shiner 2.59 mg/kg, 10 individuals). Thismay be due to greater migration of splittails into this areafrom waters downstream of the SLD outfall.

Invertebrates

In the second year of operation of the GBP, seleniumconcentrations in invertebrates in Mud Slough below theSLD outfall (Sites D and I) reached higher levels thanany found since the last drought year of 1992 whendrainwater stagnated and evapoconcentrated in MudSlough (Figures 9 and 10). Selenium in crayfish at Sites Dand I reached levels of concern (3–7 mg/kg) and in twocomposite samples exceeded the toxicity threshold of7 mg/kg (November 1998: 11.0 and 8.8 mg/kg incomposites of 7 individuals and 6 individuals respectively).During the spring and early summer of 1998, concentra-tions in waterboatmen also reached levels of concernbelow the drain (Figures 9 and 10). Upstream of the drainoutfall (Site C) selenium concentrations in invertebratesremained about the same as in previous years (Figure 11).

Mud Slough at Highway 140 (Site E)

Fish

Pre-Project selenium concentrations in whole-bodymosquitofish and inland silversides were consistentlywithin the range of selenium concentrations associatedwith no known ecological risk (<4 mg/kg whole-body).After the reopening of the SLD, selenium concentrations

immediately increased in whole-body fish and fishmuscle collected from Site E. Throughout the first andsecond year of the GBP operation, selenium concentra-tions in mosquitofish generally remained within therange of selenium concentrations associated withuncertain ecological risk (4–12 mg/kg whole-body),increasing to a peak concentration of 9.63 mg/kg in latesummer of 1997 (Figure 12). Sacramento blackfish andgreen sunfish, collected only in the summer of 1998, hadselenium concentrations of 4.96 mg/kg and 2.57 mg/kgrespectively. Similar to whole-body mosquitofish, pre-Project selenium concentrations in muscle tissue of carpwere consistently lower than the 8 mg/kg dry wt concen-tration of selenium in muscle identified as a level ofconcern that can trigger toxicity in warm water fishes(Lemly, 1993); however, since-Project selenium concen-trations in carp increased to a peak concentration of13.34 mg/kg, remaining consistently above the thresholdof concern during WY 1998 (Figure 13). The markeddecrease in selenium body burdens observed in bothforage fish and gamefish during the early summer of1998 was attributed to local effects of a prolonged springflood event within the region.

Invertebrates

Pre-Project selenium concentrations in crayfish (1.51 to2.13 mg/kg) and waterboatmen (1.64 mg/kg) wereconsistently within the range of selenium concentrationsassociated with no ecological risk (<3 mg/kg). Since thereopening of the SLD, selenium concentrations incrayfish from Site E increased to levels associated withuncertain ecological risk (3–7 mg/kg) peaking at3.85 mg/kg during the spring of the second year of GBPoperation, then decreased to levels similar to pre-Projectlevels (Figure 14). Selenium concentrations inwaterboatmen were below 3 mg/kg in both periods inwhich waterboatmen (Corixid sp.) were sampled after thereopening of the SLD (March 1997 and March 1998).The higher concentration in waterboatmen (2.71 mg/kg)occurred in the spring of 1997.

Salt Slough (Site F)

Fish

Salt Slough is a principal wetland water supply channelfrom which drainwater was to be removed by the GBP.As expected, concentrations of selenium in Salt Sloughfish had dropped substantially in 1997 to No-Effect


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Figure 3. Selenium in Medium-size Fish in Mud Slough Above the San Luis Drain Discharge (Site C)

Figure 4. Selenium in Small Fish in Mud Slough Below the San Luis Drain Discharge (Site D)

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Figure 5. Selenium in Medium-size Fish in Mud Slough Below the San Luis Drain Discharge (Site D)

Figure 6. Selenium in Small Fish in Mud Slough Backwater Below the San Luis Drain Discharge (Site I)


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Figure 7. Selenium in Medium-size Fish in Mud Slough Below the San Luis Drain Discharge (Site I)

Figure 8. Selenium in Splittails in GBP Sloughs, June 1998

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Figure 9. Selenium in Invertebrates in Mud Slough Below the San Luis Drain Discharge (Site D)

Figure 10. Selenium in Invertebrates in Mud Slough Backwater

Below the San Luis Drain Discharge (Site I)


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Figure 11. Selenium in Invertebrates in Mud Slough Above the San Luis Drain Discharge (Site C)

Figure 12. Selenium Concentrations in Whole-Body Fish Tissue from Mud Slough

at Highway 140 (Site E)

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Figure 13. Selenium Concentrations in Fish Muscle Tissue from Mud Slough


Figure 14. Selenium Concentrations in Invertebrates from Mud Slough


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Levels. However, in the aftermath of substantial releasesof drainwater into Salt Slough in February 1998,selenium concentrations in some fish rose close to orabove the threshold of concern (4 mg/kg) in March(mosquitofish: composite=3.91 mg/kg, 7 individuals;inland silverside: composite=3.86 mg/kg, 2 individuals;carp: mean composite muscle=4.3 mg/kg, 2 samples of 5individuals each; Figures 15 and 16).

Invertebrates

In Salt Slough, selenium concentrations rose above thethreshold of concern (3 mg/kg) in crayfish (compos-ite=3.15 mg/kg, 10 individuals) in March 1998 followingthe release of drainwater into Salt Slough during most ofFebruary. Otherwise, selenium concentrations in inverte-brates during the second year of the GBP remained inthe No-Effect Zone, confirming the generally improvingtrend that began to be apparent in the first year of theGBP (Figure 17). The mean concentration of selenium inall analyzed invertebrate samples collected since the GBPbegan (n=9) is significantly lower than that for all pre-Project samples (n=30) (pre-Project mean=4.23 mg/kg,since-Project mean=2.12 mg/kg, p<0.01 Student’s t-test).

San Joaquin River at FremontFord (Site G)

Fish

Site G represents the San Joaquin River site that hasbeen largely precluded from receiving Grassland areasubsurface drainage water as a result of the GBP. Pre-Project selenium concentrations in whole-bodymosquitofish, inland silversides, and fathead minnowswere highest in 1993, ranging from 6.77 to 8.65 mg/kg,consistently within the range (4–12 mg/kg) of seleniumconcentrations associated with uncertain ecological risk(Figure 18). Throughout the first and second year ofGBP operation, selenium concentrations in fish collectedfrom site G on the San Joaquin River continue to reflectremoval of local inputs of selenium-laden drainage water.Selenium concentrations in mosquitofish have trendeddownward from 4.00 mg/kg in November of 1996 to1.35 mg/kg in September of 1998, remaining within thezone of no known ecological risk. Similar results wereevident for early 1993 pre-Project selenium concentra-tions in muscle tissue of carp (11.27 mg/kg dry wt),


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Figure 15. Selenium in Small Fish in Salt Slough (Site F)

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Figure 16. Selenium in Medium-Size Fish in Salt Slough (Site F)


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Figure 17. Selenium in Invertebrates in Salt Slough (Site F)


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Figure 18. Selenium Concentrations in Whole-Body Fish Tissue from the San Joaquin River

Upstream of the Mud Slough Confluence (Site G)

Figure 19. Selenium Concentrations in Fish Muscle Tissue from the San Joaquin River


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which continued to decrease to a concentration of1.38 mg/kg (dry wt) for the last quarter reported(Figure 19). Selenium concentrations in white catfishand largemouth bass muscle collected before the GBPwere not significantly different from since-Projectconcentrations, remaining below the 8 mg/kg thresholdassociated with uncertain risk.

Invertebrates

Since the 1993 pre-Project sampling, selenium concen-trations in crayfish continued to decrease from concen-trations ranging from 1.52 to 4.70 mg/kg to a since-Project level of 0.83 mg/kg for the last quarter reported.Similar to crayfish, selenium concentrations inwaterboatmen collected since the re-opening of the SLDwere within the zone of no known ecological risk(<3 mg/kg; Figure 20).

San Joaquin River Below MudSlough (Site H)Fish

Site H represents the River site downstream of the MudSlough confluence not expected to realize any risks or

benefits as a result of GBP operation. Pre-Projectselenium concentrations in whole-body mosquitofish,fathead minnows, and red shiners were highest insummer 1993, ranging from 4.54 mg/kg to 5.79 mg/kg,then fell consistently below the 4 mg/kg uncertainecological risk zone for the remainder of pre-Projectsampling. Throughout the first and second year of GBPoperation, with the exception of mosquitofish during latefall 1997 sampling, selenium concentrations in all foragefish species, including mosquitofish, green sunfish, andbluegill fell below the threshold level of concern,remaining within the zone of no known ecological risk(Figure 21). Similarly, selenium concentrations in muscletissue of all fish species collected generally decreasedwith each sampling quarter, remaining below 8 mg/kgdry wt throughout the first and second year of GBPoperation (Figure 22). Body burdens of selenium in fishcollected from this site appear to be remaining consis-tently below levels of concern.

Invertebrates

Pre-Project selenium concentrations in crayfish andwaterboatmen from Site H ranged from 1.13 to2.42 mg/kg, within the zone of no ecological risk to

Figure 20. Selenium Concentrations in Invertebrates from the San Joaquin River


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Figure 21. Selenium Concentrations in Whole-Body Fish from the San Joaquin River

Downstreamstream of the Mud Slough Confluence (Site H)

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Figure 22. Selenium Concentrations in Fish Muscle Tissue from the San Joaquin River

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higher order consumers (<3 mg/kg; Figure 23).Throughout the first and second year of GBP operation,selenium concentrations in all invertebrate speciescollected have remained consistently below 3 mg/kg,confirming no localized impacts to date as a result ofGBP operations.

Assessment of Selenium Risk toFish

To assess overall risk to fish from selenium levels at thevarious sites affected by the GBP, the percent of compos-ite whole-body fish samples falling within each of thethree risk categories recognized in Table 1 (no effect,level of concern, and hazard) was tabulated for each siteand time period (Figures 24–26). In Mud Slough justabove the SLD outfall (Figure 24), selenium risk to fishhas remained about the same as pre-Project levels withthe exception of the first two monitoring periodsimmediately following the opening of the SLD whensome highly contaminated fish from the previouslystagnant SLD may have moved upstream in Mud Sloughand temporarily elevated the selenium concentrations ofcomposite samples taken at the upstream monitoring

location (Site C). Below the SLD outfall in Mud Sloughthe risk to fish rose sharply after the SLD was reopenedbut the risk situation then improved until March of 1998,after which the risk again increased (Figure 25). In SaltSlough, the risk to fish declined during the first year ofthe GBP, and has remained at no-risk levels throughoutthe second year of the GBP (Figure 26).

Assessment of Risk to PublicHealth from Consumption of Fish

Public health advisories warning against the consump-tion of fish from Mud and Salt sloughs are currentlyposted at property perimeter fences of KestersonReservoir and within San Luis Wildlife Refuge near SaltSlough. Popular local gamefish were collected from MudSlough (Sites D and E), Salt Slough (Site F), and theSan Joaquin River (Sites G and H) to assess currentpublic health risks. The Office of Environmental HealthHazard Assessment (OEHHA) has established a 2 mg/kg wet wt interim internal guidance and screening levelfor selenium that limits the consumption of fish byhealthy adults, and advises against any consumption bychildren or pregnant women.

Figure 23. Selenium Concentrations in Invertebrates from the San Joaquin River

Downstream of the Mud Slough Confluence (Site H)

0

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Figure 24. Risk to Fish Due to Selenium in Mud Slough Above the San Luis Drain Outfall

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Figure 25. Risk to Fish Due to Selenium in Mud Slough Below the San Luis Drain Outfall

111


During the late summer sampling quarter of boththe first and second year of GBP operation, gamefishcollected from Mud Slough at Site E exceeded the2 mg/kg wet wt selenium health screening level, peakingat 2.64 mg/kg wet wt in September of 1997. During allother sample periods throughout the first and secondyear of GBP operation, those same gamefish haveremained below the 2 mg/kg health screening level.Gamefish from Sites G and H on the San Joaquin Riverhave remained consistently below the 2 mg/kg healthscreening level throughout the first and second year ofGBP operations, rarely exceeding a selenium concentra-tion of 1 mg/kg wet wt.

Selenium in Bird Eggs

In duck eggs collected in the Mud Slough area (Figure28), the mean selenium concentration increased some-what (1996 mean 2.6 mg/kg; 1997 mean 2.9 mg/kg;1998 mean 3.8 mg/kg), exceeding the threshold ofconcern for bird populations (3 mg/kg) in 1998. How-ever, the increase was not statistically significant (1996versus 1998 p=0.12; 1997 versus 1998 p=0.18 Student’s1-tail t-test). The variation in selenium concentrations induck eggs increased to a much greater extent (Figure 27).The maximum selenium concentration in duck eggs rose

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Figure 26. Risk to Fish Due to Selenium in Salt Slough

Figure 27. Selenium in Duck Eggs Near Mud Slough


112

Figure 28

Selenium Concentrations in Duck Eggs

Gun Club Road

San Luis Drain

M e r c e d R i v e r

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Figure 29

Selenium Concentrations in Shorebird Eggs

1996 1997 1998

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No Effect (< 3)

Gun Club Road

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Figure 30. Selenium in Killdeer EggsNear Mud Slough and San Luis Drain

Figure 31. Selenium in Duck EggsNear Salt Slough

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from 3.3 mg/kg in 1998 (pre-Project) to 4.2 mg/kg in1997 and to 6.6 mg/kg in 1998.

In 1998, as in 1997, the maximum concentration inkilldeer eggs collected along the SLD (Figure 29)reached a very high level (35 mg/kg in 1997; 28 mg/kgin 1998), far exceeding the toxic threshold (8 mg/kg)(Figure 30).

In the Salt Slough area in the first year of theGBP (1997), mean selenium concentration in duck eggshad declined from the pre-Project (1996); the mean roseagain somewhat in 1998 (geometric mean=2.9 mg/kg in1996, 1.8 mg/kg in 1997, 2.4 mg/kg in 1998; Figure 31).However, none of these changes were statisticallysignificant.

In killdeer eggs, as in duck eggs, selenium concen-trations near Salt Slough (Figure 29) had dropped in thefirst year of the GBP, but rose again in 1998 (Figure 32).Sample sizes of two and three eggs were too small forstatistical significance. In 1998, eggs were collected inJune, four months after substantial amounts ofdrainwater were released into Salt Slough duringFebruary storms.

Aquatic Hazard Assessment ofSelenium

To provide an estimate of ecosystem-level effects ofselenium, Lemly (1995, 1996) developed an aquatichazard assessment procedure that sums the effects ofselenium on various ecosystem components to yield asingle characterization of overall hazard to aquatic life.

Lemly’s procedure applied to Salt Slough indicated areduction in selenium hazard from “high” before theGBP, to “moderate” in WY 1997, the first year ofoperation of the GBP. But in the second year of the GBP(WY 1998) Lemly’s hazard index for Salt Slough roseagain to “high” (Table 2). The increase in the overallindex was driven mainly by increases in maximumselenium concentrations in sediment and in aquaticmacroinvertebrates in the aftermath of substantialreleases of drainwater mixed with sediment-ladenstormwater runoff through most of the month ofFebruary 1998.

In the wetland area most adversely affected by thereopening of the SLD (Mud Slough below the SLDoutfall), Lemly’s hazard assessment procedure indicatesthat in the second year of the GBP the selenium hazardfurther increased well into the “high” range after previ-ously increasing from “moderate” before the GBP to thelow end of “high” in the first year of the GBP (Table 2).The increased hazard in 1998 is mainly due to highermaximum concentrations of selenium in water at Site D(just below the SLD outfall) in late May 1998 and insediment at Site E in November 1997. Seleniumelevation in aquatic macroinvertebrates at Site I inNovember 1997 also contributed to the increase in thehazard index.

The above assessments incorporate data for waterfrom Central Valley Regional Water Quality ControlBoard and data for sediment from the USBR in additionto biological data collected by the USFWS. In accor-dance with Lemly’s protocol, the assessments use the

Figure 32. Selenium in Killdeer Eggs

Near Salt Slough


116

highest (rather than the mean) concentrations ofselenium found in each of the ecosystem components.Data from the biological sampling in November 1996,shortly after GBP initiation, were excluded from the WY1997 hazard assessments because temporarily extremelyhigh concentrations of selenium in some fish may havebeen due to those fish having been flushed out of thepreviously stagnant, evapoconcentrated SLD. Very highlevels of selenium in the water associated with stormflows were not excluded because elevated concentrationspersisted long enough (especially in February 1998) topotentially adversely affect the ecosystem. Data fromkilldeer eggs collected along the SLD were excludedbecause these birds probably ingested selenium mainlyfrom feeding in the Kesterson area rather than from thearea influenced by the GBP. Nevertheless, invertebratesfrom the SLD itself may contribute to their diet (GarySantolo, pers. com.). Concentrations of selenium in fisheggs were estimated from whole-body concentrationsusing the conversion factor (fish egg selenium = fishwhole-body selenium X 3.3) recommended in Lemly(1995, 1996).

Boron in fish

Boron concentrations in mosquitofish in Mud Sloughbelow the SLD discharge dropped in 1998 (mean=4.6mg/kg) to within the range of pre-Project compositeconcentrations (mean 6.4 mg/kg, range 2–13, S.D.=3.6)after reaching a substantially higher level (16 mg/kg) inSeptember 1997 (Figure 33). In Salt Slough, which was

BEFORE PROJECT SINCE PROJECT

1995–Sept. 1996 WY 1997 WY 1998

concentration score hazard concentration score hazard concentration score hazard

Mud Slough below Drain outfall

Water 19.4 µg/L 5 high 79.6 µg/L 5 high 104.0 µg/L 5 highSediment 0.4 µg/g 1 none 0.76 µg/g 1 none 2.0 µg/g 3 lowInvertebrates 1.6 µg/g 1 none 3.3 µg/g 3 low 11 µg/g 5 high*Fish eggs 14.2 µg/g 4 moderate 56.1 µg/g 5 high 34.2 µg/g 5 highBird eggs 3.12 µg/g 2 minimal 4.38 µg/g 2 minimal 6.64 µg/g 4 lowTOTAL 13 moderate 16 high 22 high

Salt Slough

Water 37.8 µg/L 5 high 3.4 µg/L 4 moderate 5.1 µg/L 5 highSediment 0.8 µg/g 1 none 0.94 µg/g 1 none 2.1 µg/g 3 lowInvertebrates 4.7 µg/g 4 moderate 2.6 µg/g 2 minimal 3.15 µg/g 3 low*Fish eggs 28.1 µg/g 5 high 17.8 µg/g 4 moderate 12.9 µg/g 4 moderateBird eggs 5.2 µg/g 3 low 3.58 µg/g 2 minimal 3.72 µg/g 2 minimalTOTAL 18 high 13 moderate 17 high

Hazard scale for total score: 5, no hazard; 6–8, minimal hazard; 9–11, low hazard; 12–15, moderate hazard; 16–25, high hazard.•Fish egg concentrations calculated from whole-body, see text.

Table 2. Aquatic Hazard Assessment of Selenium in Mud and Salt Slough Areas.

expected to benefit from the GBP, boron concentrationsin mosquitofish rose in March 1998 (3.17 mg/kg) aftersubstantial release of drainwater into Salt Slough inFebruary 1998 (Figure 34). Concentrations remainedelevated above WY 1997 levels for the remainder ofWY 1998. Nonetheless the mean WY 1998 concentra-tion (2.3 mg/kg) remained below the pre-Project mean(6.4 mg/kg, p=0.066 Student’s 1-tail t-test). Insufficientinformation is available at this time to evaluate thehazard of these concentrations of boron to fish or toanimals that consume fish.

ConclusionsIn the second year of operation of the GBP, contaminanteffects on wildlife evidently improved in some geo-graphic areas and taxa but worsened in others. In MudSlough below the SLD outfall, selenium concentrationsin fish trended downward (still at levels of concern),while selenium concentrations rose in somemacroinvertebrates (waterboatmen). The release ofdrainwater into the wetlands channels feeding SaltSlough was sufficiently prolonged (February 3–28, 1998)to adversely affect contaminant concentrations in theSalt Slough ecosystem, temporarily reversing theimprovement that occurred during the first year of theGBP. Throughout the second year of GBP operation,selenium concentrations in biota from the San JoaquinRiver continued to remain within zones of no knownecological risk.

117



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Figure 33. Boron in Mosquitofish in Mud Slough Below the San Luis Drain Discharge (Site D)


118

AcknowledgmentsWe greatly appreciate the assistance provided in the fieldby Carmen Thomas, Joy Winckel, Jerry Bielfeldt, RuthElbert, Kyle Merriam, Jason Davis, Meri Moore, PatrickLeonard, Mike Morse and Larry Thompson from theSacramento Fish and Wildlife Service Office (SFWSO),and by Karine Sande, Ivette Loredo, Victor Lyon, JasonRoss, Mark Fisher, Scott Stevens, Bruce Barbour, SheriMelanson, Leann Tripson, Dennis Woolington, ScottFrazer, Mike Peters, and Gary Zahm from the San LuisNational Wildlife Refuge Complex. We are also gratefulfor the field assistance provided by Curtis Hagen, ToddNewhouse, Robert Vincik, Brad Burkholder, Jim Starr,Steve Cordes, and Keith Whitener from the CentralValley Bay-Delta Branch of the California Departmentof Fish and Game. We thank Don Stevens of theCentral Valley Bay-Delta Branch for generously provid-ing us with the use of his hunting dogs, and we thankJohn Beam, Chantelle Carroll, Jennifer Isola, and LeslieHoward, California Department of Fish and Game, forhelping us collect avian eggs on the Los Banos WildlifeManagement Area. Carmen Thomas from the SFWSOgenerously assisted us in preparing samples.


Compliance Monitoring Program for Use andOperation of the Grassland Bypass Project (FinalDraft). Prepared for the U.S. Bureau of Reclama-tion, Sacramento, CA.

Engberg, A., D.W. Westcot, M. Delamore, and D.D.Holz. 1998. Federal and State Perspectives onRegulation and Remediation of Irrigation-Induced Selenium Problems. In EnvironmentalChemistry of Selenium. W.T. Frankenberger, Jr.and R.A. Engberg, eds. Marcel Dekker, Inc., NY.

Lemly, A.D. 1993. Guidelines for Evaluating SeleniumData from Aquatic Monitoring and AssessmentStudies. Environ. Monitor. Assess., 28:83–100.

Lemly, A.D. 1995. A Protocol for Aquatic HazardAssessment of Selenium. Ecotoxicology Environ.Safety., 32:280–288

Lemly, A.D. 1996. Assessing the toxic threat of seleniumto fish and aquatic birds. Environ. Monitor. Assess.,43:19–35.

Lemly, A.D. and G.J. Smith. 1987. Aquatic Cycling ofSelenium: Implications for Fish and Wildlife. Fishand Wildlife Leaflet 12, U.S. Department of theInterior, Fish and Wildlife Service, Washington, DC.

NIWQP (U.S. Department of Interior, National IrrigationWater Quality Program). 1998. Guidelines for DataInterpretation for Selected Constituents in Biota,Water, and Sediment. National Irrigation WaterQuality Program Report No. 3, November 1998.

Saiki, K., M.R. Jennings and S.J. Hamilton. 1991.Preliminary Assessment of the Effects of Seleniumin Agricultural Drainage on Fish in the SanJoaquin Valley. In The Economics and Manage-ment of Water and Drainage in Agriculture, A.Dinar and D. Ziberman, eds. Kluwer AcademicPublishers, Boston, MA.

Skorupa, P. 1998. Selenium Poisoning of Fish andWildlife in Nature: Lessons from Twelve Real-World Examples. In Environmental Chemistry ofSelenium. W.T. Frankenberger, Jr. and R.A.Engberg, eds. Marcel Dekker, Inc., NY.

Skorupa, P., S.P. Morman, and J.S. Sefchick-Edwards.1996. Guidelines for Interpreting SeleniumExposures of Biota Associated with NonmarineAquatic Habitats. Prepared for the Department ofInterior, National Irrigation Water QualityProgram by the Sacramento Field Office of theU.S. Fish and Wildlife Service. March 1996. 74 pp.

Suter, G.W. 1993. Retrospective Risk Assessment.Chapter 10 in Ecological Risk Assessment. G.Suter, ed. Lewis Publishers, Boca Raton, FL.

U.S. Bureau of Reclamation. 1995. Finding of NoSignificant Impact and Supplemental Environ-mental Assessment. Grassland Bypass ChannelProject. Interim Use of a Portion of the San LuisDrain for Conveyance of Drainage Water Throughthe Grassland Water District and AdjacentGrassland Areas. November 1995. U.S. Bureau ofReclamation, Mid-Pacific Region, Sacramento CA.

U.S. Bureau of Reclamation and the San Luis and Delta-Mendota Water Authority. 1995. Agreement forUse of the San Luis Drain. Agreement No. 6-07-20-W1319. November 3, 1995.

U.S. Bureau of Reclamation, U.S. Fish and WildlifeService, San Luis & Delta-Mendota WaterAuthority, and U.S. Environmental ProtectionAgency. 1995. Consensus Letter to Karl Longley,Chairman, Central Valley Regional Water QualityControl Board. Subject: Basin Plan Amendmentfor the San Joaquin River. November 3, 1995.

U.S. Fish and Wildlife Service. 1995. Standard Opera-tion Procedures for Environmental ContaminantOperations, Vols. I - IX. Quality Assurance andControl Program, U.S. Fish and Wildlife Service,Division of Environmental Contaminants, QualityAssurance Task Force. Washington DC.

119

Chapter 7: Selenium in Sediment

Chapter 7

Selenium inSediment

Tim McLaughlinU.S. Bureau of Reclamation


120

PurposeSediment monitoring focuses on annual and quarterlymeasurements in San Luis Drain (SLD) and sloughsediments. Quarterly monitoring is intended to provide amore continuous characterization of sediment seleniumadsorption/desorption rates as they relate to seleniumloading in the water column. The annual measurementsprovide an intensive once-yearly sampling of SLDsediments for comparison with California Department ofHealth Services’ hazardous waste criterion for selenium.

MethodsSan Luis Drain sediment samples are collected using anacrylic coring device. After extracting the sediment, eachof the two layers is slowly extruded using a non-metallicinternal pushing device. Two layers of sediment (0–3 cmand 3–8 cm) from each of the three sampling pointsalong a transect and an entire column sample are placedin separate three-quart mixing bowls for compositing.The sediment is composited by hand mixing in a mannersimilar to kneading bread. Composited samples are thenplaced in a wide-mouth polyethylene container andstored in an ice chest at 4°C.

Sediment samples were collected in March, June,September, and November from Sites A through F asidentified in the Quality Assurance Project Plan (Entrix,Inc., 1997. These sampling periods correspond with thebiota sampling events of the U.S. Fish and WildlifeService (USFWS).

All sites were sampled for the year with theexception of Sites C, D, and E during the Marchcollection period due to high storm runoff, and Site Eduring the June sampling period due to high water fromthe San Joaquin River. In June 1997, permanent siteswere agreed upon for the annual in-drain sedimentsampling. These are sites in addition to SLD Sites A andB and are located between checks 1 and 2, 10 and 11, 14and 15, and 17 and 18. At the request of the USFWS,sediment sampling for Site F was moved in September1997 from Salt Slough at Lander Avenue to a locationupstream on the San Luis National Wildlife Refuge usedby USFWS for biota monitoring.

ResultsAs in previous years, a review of the data (Table 1,Figures 1–6) illustrates how difficult it can be to identifytrends in selenium concentrations in SLD sediments in

the short term. Site A (Figure 1) had noticeably elevatedlevels of selenium in March 1998, but lower concentra-tions in June 1998. Site B (Figure 2) has shown a gradualdecrease during the 1998 sampling period after severalyears of gradually increasing values. Site D (Figure 4),Mud Slough below the SLD terminus, has shown similarfluctuations with elevated results in June, and lowervalues in November and September. Site E (Figure 5)which has shown a gradual rise in selenium levels duringthe 1996 and 1997 sampling periods, showed a signifi-cant drop in September 1998. Data for the March andJune periods at this site were not collected due to highwater conditions. These abnormally high water periodsmay account for lower selenium levels in September dueto changes in bottom sediments either through scour ordeposition. Site F (Figure 6) showed unusually highlevels of selenium through most of the sampling periods,but returned to a lower level during the last quarter. Asin previous annual sampling periods, selenium values atSite I for 1998 remained at low levels (Table 4).

Following three years of data collection with theGrassland Bypass Monitoring Program, the mostrelevant quality assurance issue relative to the sedimentsampling effort appears to continue to be data compara-bility. The heterogeneity of selenium levels present in thebottom sediments of the SLD makes it difficult to assesswhether changes in selenium concentrations are trulyoccurring (Table 5).

Both replicate and duplicate samples of SLDbottom sediments were collected in an effort to demon-strate the heterogeneity of this material. Replicatesamples, as described by the U.S. Bureau of Reclamation(USBR), are co-located samples collected at the same site.In this effort, three sediment cores were collected at eachsite, composited, and homogenized (thoroughly mixed)into a single sample for analysis. Immediately followingcollection of the first sample, this procedure was repeatedwith three new cores collected within a foot of where the

Site A 0–3 cm 3–8 cm Whole Core

November 18, 1997 NT NT NTMarch 3, 1998 18 150 98June 4, 1998 2.8 12 7.0September 28, 1998 8.5 23 52

Table 1. Grassland Bypass Program

San Luis Drain Sediment Monitoring

Selenium Levels (µg/g dry weight)

121


original cores were sampled. The two samples were thensubmitted to the laboratory to measure the relativepercent difference (RPD) of selenium between the two.Duplicate samples, as described by USBR, are two ormore samples or aliquots taken from the same homog-enized parent material and submitted to the laboratory astwo discrete samples. In this effort, three sediment coreswere collected at a site and composited and homogenizedinto a single mixture. Following the homogenization step,the sediment was transferred into two sample containersand sent to the laboratory as two discrete samples.

As evident in Table 2, the replicate sedimentsamples show RPDs ranging from 53% to 76%. Thesesignificant RPDs can be attributed to three plausiblefactors including, sample handling error (the sampleswere not well mixed prior to sample analysis), error wasintroduced at the laboratory (poor sample preparation,bias, or contamination introduced), or the bottomsediments are very heterogeneous. The precision in thesix duplicate sample results as presented in Table 3 areindicative that the field homogenization process isacceptable and should not be considered the source ofthe imprecision. Both internal and external qualitycontrol (QC) check sample results appear to eliminatethe laboratory as the source of the problem. It wouldappear that selenium concentrations are variable in theSLD sediments.

Again since all the internal QC and nearly all theexternal QC check samples met the acceptance criteriafor data validity, the problem does not appear to belaboratory related, but rather it lies with comparability ofdata from one sampling period to the next. The composi-tion of the sediment material is such that both recent andpast studies have shown samples collected very short

distances from one another can have selenium levelsdiffering by more than an order of magnitude.

Heterogeneity in the bottom sediments of theSLD makes assessment of temporal changes in seleniumlevels difficult, if not impossible, until a statistically validtrend can be established. Gross characterization of themean selenium level as it relates to the hazardous wastelevel can be made, but detecting any small changes as aresult of the chemical and biological processes willcontinue to be difficult. This concern has been broughtto the attention of the Data Collection and ReportingTeam and is currently under review.

Even with the difficulty of assessing a non-homogeneous mixture such as the SLD bottom sedi-ments, at no time during the 1998 sampling period didselenium levels exceed the 100 µg/g wet weight hazard-ous material criterion established by the CaliforniaDepartment of Health Services.

The conversion from dry wet weight to wet weightis made by the following formula:

wet weight = (dry weight) * (1.0 - percent moisture/100.0)

Using the value of 150 dry weight from Table 5, March3, 1998, 3–8 cm, and a percent moisture value of 63.3, acomputed selenium wet weight is 55 µg/g. The nextquarterly data summary report will provide percentmoisture values for the entire sediment database.



Site 14/15C Se Results Rep. Se Results % RPD

(µg/g dry weight) (µg/g dry weight)

0–3 cm 31 14 76%3–8 cm 11 19 53%Whole Core 42 24 55%

Table 2. Annual Sediment Monitoring—June 1998


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Site Location Selenium Level Relative Percent Difference (RPD)

(µg/g dry weight) (%)

SLD 17/18A (whole) 75/79 µg/g 5.2Site A (whole) 7.0/6.6 µg/g 5.1SLD 1/2 B (3-8) 68/76 µg/g 11Site D (3-8) 1.2/1.1 µg/g 8.7SLD 10/11C (3-8) 39/39 µg/g 0.0SLD 10/11A (0-3) 18/22 µg/g 20

Table 3. Quality Assurance Results

GBP Sediment Monitoring Program Conducted June 3–4, 1998.

Duplicates To Measure Laboratory Precision

Table 4. Site I: Selenium in Sediment

Sampling Date Selenium Concentration

0–3 cm 3–8 cm Whole Core

µg/g, dry weight µg/g, dry weight µg/g, dry weight

Jun 13, 1996 0.4 0.4 0.3Mar 13, 1997 1.5 0.8 0.4Jun 03, 1998 0.3 0.2 0.2

NT = Not Tested

123


Sampling Date Selenium Concentration

0–3 cm 3–8 cm Whole Core

µg/g, dry weight µg/g, dry weight µg/g, dry weight

Site BMar 12,1996 NT NT NTJun 27,1996 19 12 30Sep 4,1996 11 18 20Nov 12,1996 24 41 40Mar 13,1997 26 48 42Jun 10,1997 14 27 0.11Sep 11,1997 21 61 48Nov 18,1997 15 28 41Mar 3,1998 18 41 45Jun 3,1998 11 21 26Sep 29,1998 13 15 NT

Midpoint of Checks 1 & 2Mar 13,1996 20 43 26Jun 10,1997 39 96 51Jun 3,1998 64 68 8.3

30' South of Check 1Feb 13,1996 11 30 14Jun 10,1997 9.6 47 26Jun 3,1998 22 9.7 29

50' South of Check 10Feb 13,1996 12 18 26Jun 10,1997 7.2 15 31Jun 4,1998 21 39 17

Midpoint of Checks 10 & 11Mar 13,1996 4.3 4.1 9.0Jun 10,1997 11 12 NTJun 4,1998 7.5 8.7 17

50' North of Check 11Mar 13,1996 7.0 14 23Jun 10,1997 24 43 39Jun 4,1998 18 55 50

50' South of Check 14Jun 11,1997 7.1 34 8.0Jun 4,1998 31 11 42

Midpoint of Checks 14 & 15Jun 11,1997 2.9 22 10Jun 4,1998 3.4 3.4 5.7

50' North of Check 15Jun 11,1997 40 48 3.8Jun 4,1998 29 47 59

50' South of Check 17 (Site A)Mar 13,1996 2.0 16 10Jun 27,1996 8.0 20 29Sep 4,1996 3.4 24 7.7Nov 12,1996 22 62 55Mar 12,1997 NT NT NTJun 10,1997 2.9 4.2 5.4Sep 11,1997 38 56 50Nov 18,1997 NT NT NTMar 3,1998 18 150 98Jun 4,1998 2.8 12 7.0Sep 28,1998 8.5 23 52

Midpoint of Checks 17 & 18Jun 10,1997 2.7 3.5 3.8Jun 3,1998 2.0 2.8 2.7

50' North of Check 18Mar 13,1996 13 17 35Jun 10,1997 48 66 100Jun 3,1998 35 65 75

NT = Not Tested

Table 5. San Luis Drain: Selenium in Sediment, March 1996–September 1998


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Sampling Date 0–3 cm 3–8 cm Whole Core

Mar 13,1996 2.0 16 10Jun 27,1996 8.0 20 29Sep 4,1996 3.4 24 7.7Nov 12,1996 22 62 55Mar 12,1997 NT NT NTJun 10,1997 2.9 4.2 5.4Sep 11,1997 38 56 50Nov 18,1997 NT NT NTMar 3,1998 18 150 98Jun 4,1998 2.8 12 7.0Sep 28,1998 8.5 23 52

NT = Not Tested

Site A


Mar 12,1996 NT NT NTJun 27,1996 19 12 30Sep 4,1996 11 18 20Nov 12,1996 24 41 40Mar 13,1997 26 48 42Jun 10,1997 14 27 0.11Sep 11,1997 21 61 48Nov 18,1997 15 28 41Mar 3,1998 18 41 45Jun 3,1998 11 21 26Sep 29,1998 13 15 NT

NT = Not Tested

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Figure 2. Site B: Selenium in Sediment

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Figure 3. Site C: Selenium in Sediment

Figure 4. Site D: Selenium in Sediment


Mar 12,1996 NT NT NTMay 20,1996 0.2 0.2 0.1Jun 27,1996 0.1 <0.1 0.1Sep 4,1996 0.3 0.1 <0.1Nov 12,1996 0.16 0.17 0.31Mar 12,1997 0.15 <0.10 0.11Jun 9,1997 0.11 0.20 <0.10Sep 11,1997 0.23 0.12 0.44Nov 17,1997 0.10 0.10 0.10Mar 3,1998 NT NT NTJun 4,1998 0.26 0.31 0.10Sep 28,1998 0.40 0.35 0.31

NT = Not Tested

Site C


Mar 12,1996 NT NT NTApr 3,1996 <0.1 0.1 <0.1Jun 27,1996 0.4 0.4 0.2Sep 4,1996 0.2 0.2 0.2Nov 13,1996 0.14 0.25 0.17Mar 12,1997 0.46 0.27 0.76Jun 9,1997 0.12 <0.10 0.16Sep 11,1997 0.53 0.29 0.33Nov 17,1997 0.72 0.24 0.24Mar 3,1998 NT NT NTJun 3,1998 0.63 1.20 1.30Sep 29,1998 0.64 0.47 0.50

NT = Not Tested

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Figure 5. Site E: Selenium in Sediment

Figure 6. Site F: Selenium in Sediment


Mar 12,1996 NT NT NTMay 20,1996 0.1 0.1 0.1Jun 27,1996 0.1 0.1 <0.1Sep 4,1996 NT NT NTNov 13,1996 0.72 0.71 0.70Mar 13,1997 0.82 1.00 1.00Jun 9,1997 1.50 1.60 1.50Sep 11,1997 1.60 1.30 1.90Nov 17,1997 0.83 2.00 1.20Mar 3,1998 NT NT NTJun 3,1998 NT NT NTSep 29,1998 0.24 0.18 0.25

NT = Not Tested

Site E


Mar 12,1996 NT NT NTJun 27,1996 0.6 0.5 0.2Sep 5,1996 0.4 0.8 0.4Nov 13,1996 0.24 0.40 0.25Mar 13,1997 0.94 0.36 0.57Jun 9,1997 0.12 0.14 0.35Sep 12,1997 0.59 0.73 0.74Nov 18,1997 1.30 1.90 1.40Mar 4,1998 2.10 1.80 1.60Jun 4,1998 0.66 1.00 1.30Sep 29,1998 0.33 0.48 0.59

NT = Not Tested

Site F

127

Chapter 8: Sediment in Drain

Chapter 8

Sediment in Drain

Joseph C. McGahan, Drainage CoordinatorGrassland Area Farmers


128

The purpose of this aspect of the Grassland BypassMonitoring Program (Monitoring Program) is to deter-mine the changes in quantity and movement of sedimentin the San Luis Drain (SLD). This is accomplished byactual measurement of the sediment and using totalsuspended solids measurements at the inlet and outlet ofthe SLD.

Sediment QuantityMonitoring Performedby the San Luis andDelta-Mendota WaterAuthoritySection 4.4.1 of the Compliance Monitoring Program(USBR et al., 1996) describes the procedure to measurethe quantity of sediment in SLD. The MonitoringProgram calls for the measurement of sediment in fourreaches of the SLD (Reaches 1, 11, 15, and 18). Mea-surements of sediment depths were to be made using aprescribed method at locations measured in March of1987 during a previous survey. The Monitoring Programcalls for measurements to be made once per year.

The sediment in SLD was measured in all 19reaches of the Grassland Bypass Project (GBP) whichincluded the four required reaches. Measurements weremade in accordance with the Monitoring Program. Theresults were reported by reach in comparison to theMarch 1987 survey.

Table 1 summarizes the results. The results are alsoshown graphically in Figure 1. They indicate that thereappears to be an increase of 21,812 cubic yards from 1997to 1998, compared to an increase of 2,500 cubic yards from1987 to 1997. This increase can likely be attributed to thesevere February 1998 storm events in which high sedimentconcentration flood waters were conveyed in the SLD.Additional sediment associated with wind and mainte-nance activities may have also contributed.

Total Suspended SolidsMeasurementsThe Monitoring Program calls for total suspended solids(TSS) measurements as part of the water quality monitor-ing. These measurements were to be taken just down-stream of the inlet to SLD (Site A) and just upstream ofthe outlet (Site B). Measurements were taken on a weekly

March 1987 June–Sept. 1997 July 1998

Pool Checks Distance Volume Vol / mile Volume Vol / mile Volume Vol / mile

(miles) (cu yd) (cu yd/mi) (cu yd) (cu yd/mi) (cu yd) (cu yd/mi)

End End to 1 2.64 3,176 1,203 1,697 643 2,795 1,0591 * 1 to 2 1.82 2,567 1,410 1,840 1,011 3,375 1,8542 2 to 3 0.28 1,059 3,781 531 1,896 955 3,4113 3 to 4 2.57 4,909 1,910 3,350 1,304 4,839 1,8834 4 to 5 1.8 4,440 2,467 6,521 3,623 9,049 5,0275 5 to 6 2.06 4,242 2,059 4,370 2,121 4,596 2,2316 6 to 7 0.83 2,160 2,602 2,584 3,113 2,432 2,9307 7 to 8 0.45 3,935 8,744 3,278 7,285 3,135 6,9678 8 to 9 0.47 907 1,931 816 1,736 778 1,6559 9 to 10 3.2 6,963 2,176 6,390 1,997 8,571 2,678

10 * 10 to 11 1.46 2,647 1,813 2,708 1,855 2,781 1,90511 11 to 12 2.5 4,835 1,934 4,947 1,979 7,620 3,04812 12 to 13 0.46 784 1,705 909 1,977 1,504 3,27013 13 to 14 0.91 2,038 2,240 1,771 1,946 2,657 2,92014 * 14 to 15 1.34 2,304 1,719 3,803 2,838 5,427 4,05015 15 to 16 0.96 1,822 1,898 2,700 2,813 6,456 6,72516 16 to 17 1.68 5,863 3,490 7,605 4,527 10,482 6,23917 * 17 to 18 0.68 1,885 2,772 3,006 4,420 2,435 3,58118 18 to 19 0.97 1,558 1,607 1,768 1,822 2,519 2,597

Total to Ck. 19 27.08 58,094 2,145 60,594 2,238 82,406 3,370

* Required by Grassland Bypass Monitoring Program

Table 1. 1998 San Luis Drain Sediment Survey

Survey Summary and Comparison

129

Chapter 8: Sediment in Drain

0

1,000

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1987 Survey (Summers Eng.) 1997 Survey (SLDMWA) 1998 Survey (SLDMWA)

Figure 1. San Luis Drain Sediment Survey Comparison

basis at these sites. The data are shown in Table 2. Thedata show that TSS concentrations at Site A are higherthan at Site B, by a factor of 1.1 to 4.6 based on monthlyaverages. One commitment of the GBP was to minimizeflows so as to not cause sediment movement or suspen-sion of sediments from the bottom of SLD. The datasuggest that the sediments are settling in SLD and thatthere is no net movement or suspension of sediments.

ReferencesU.S. Bureau of Reclamation et al. 1996. Compliance

Monitoring Program for Use and Operation of theGrassland Bypass Project, September 1996. U.S.Bureau of Reclamation, Mid-Pacific Region,Sacramento, CA.


130

Table 2. Total Suspended Solids

Site A Site B

Date TSS Date TSS

(mg/L) (mg/L)

02-Oct-97 NA08-Oct-97 89 09-Oct-97 2615-Oct-97 34 16-Oct-97 3222-Oct-97 12 24-Oct-97 1329-Oct-97 70 30-Oct-97 2505-Nov-97 77 06-Nov-97 2812-Nov-97 62 14-Nov-97 1119-Nov-97 74 19-Nov-97 NA25-Nov-97 130 25-Nov-97 1703-Dec-97 61 05-Dec-97 3310-Dec-97 28 11-Dec-97 3817-Dec-97 NP 18-Dec-97 NP23-Dec-97 NP 26-Dec-97 1730-Dec-97 45 02-Jan-98 2807-Jan-98 42 08-Jan-98 1114-Jan-98 NA 15-Jan-98 3421-Jan-98 67 22-Jan-98 1728-Jan-98 79 29-Jan-98 2804-Feb-98 260 05-Feb-98 11011-Feb-98 NP 11-Feb-98 NP18-Feb-98 240 19-Feb-98 7925-Feb-98 230 26-Feb-98 24004-Mar-98 180 05-Mar-98 13011-Mar-98 180 12-Mar-98 6618-Mar-98 340 19-Mar-98 12025-Mar-98 460 26-Mar-98 14001-Apr-98 230 02-Apr-98 8708-Apr-98 170 09-Apr-98 7515-Apr-98 170 16-Apr-98 6022-Apr-98 150 23-Apr-98 5629-Apr-98 249 30-Apr-98 6706-May-98 320 07-May-98 7513-May-98 1100 14-May-98 NP20-May-98 320 21-May-98 12027-May-98 170 28-May-98 6403-Jun-98 62 04-Jun-98 4410-Jun-98 150 11-Jun-98 4617-Jun-98 140 18-Jun-98 3224-Jun-98 140 25-Jun-98 4601-Jul-98 140 02-Jul-98 4708-Jul-98 220 09-Jul-98 5115-Jul-98 280 16-Jul-98 P22-Jul-98 110 23-Jul-98 7729-Jul-98 104 30-Jul-98 1905-Aug-98 81 06-Aug-98 3112-Aug-98 160 12-Aug-98 5219-Aug-98 150 20-Aug-98 4826-Aug-98 41 27-Aug-98 4402-Sep-98 26 03-Sep-98 NP09-Sep-98 46 10-Sep-98 1116-Sep-98 50 17-Sep-98 NP23-Sep-98 39 24-Sep-98 5530-Sep-98 17

Source of data: Grassland Bypass Monitoring ProgramNA Not analyzed—data not availableNP Not provided—future unknownP Pending, data will be available in the future.

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Chapter 9: Quality Control

Chapter 9

Quality Control

Victor StokmanisU.S. Bureau of Reclamation


132

Data Quality ObjectivesThe generated data for the Grassland Bypass MonitoringProgram (Monitoring Program) must be of a high degreeof reliability. Sample collection from different environ-mental media and analytical work conducted by severallaboratories must be performed in a manner that ensureshigh data quality. This level of quality is necessary toaccurately assess compliance with selenium load dis-charge to Mud Slough and the San Joaquin River,changes to the ecosystems of the local waterways, andchanges to selenium levels in the bottom sediments of theSan Luis Drain (SLD). A quality assurance project plan(QAPP) was developed in conjunction with the monitor-ing plan to assist the investigator in evaluating the data.

Quality AssuranceProject PlanData quality objectives (DQOs) for the MonitoringProgram are defined in the QAPP, and each agency hasestablished DQOs for all environmental measurements.Both quantitative quality goals, including precision,accuracy, and completeness, along with qualitative qualitygoals, including representativeness and comparability,have been addressed in the QAPP.

The QAPP is inclusive of all the requirementsidentified in the August 1994 Draft Interim Final, U.S.EPA Requirements for Quality Assurance Project Plans forEnvironmental Data Operations, EPA QA/R-5. Itdescribes quality assurance/quality control (QA/QC)protocol associated with each agency’s sample collectionand laboratory activities, provides acceptance criteria fordata validation purposes, and describes corrective actionsto be taken when data fail to meet such criteria. TheQAPP is specifically tailored to provide the necessaryprotocol for the documentation of QA/QC activities.

Quality AssuranceOversight

The U.S. Bureau of Reclamation (USBR) isresponsible for QA/QC oversight for the MonitoringProgram. A QA/QC oversight manager (QAQCOM)serves in a cooperative capacity to ensure that thecommitments, guidelines, and protocols outlined in the

QAPP are implemented in compliance with the goalsand objectives of the GBP. This oversight role is carriedout by the QA staff of USBR’s Mid-Pacific Regionlocated in Sacramento, California. USBR staff monitorand validate data collected by USBR personnel andassess the data collection and validation processes usedby the other participating agencies. When a noncompli-ance QA issue is identified, agency QA officers arenotified, and the agency implements corrective actions toresolve the problem. Any unresolved issues between theQAQCOM and a participating agency QA officer isbrought to the attention of the Data Collection andReporting Team (DCRT) for resolution.

As part of the QA oversight responsibility, USBRQA staff have conducted audits of all participatingenvironmental laboratories. In addition, most of the datacollection activities have also been reviewed for adher-ence to protocol.

Sampling groups participating in the MonitoringProgram conduct system audits of the sampling effortsmade by other agencies in the program.

Quality AssuranceAccomplishmentsLaboratory Performance andSystem Audits

USBR’s QA staff have performed system audits of thefollowing laboratories:

Laboratory + Location Date(s) Analysis TypeSouth Dakota State University July 7 & 8, 1997 Water AnalysisLaboratory in Sioux Falls,South Dakota

Twining Laboratory in Fresno January 24 & 25, 1995 Water Analysis

Trace Substances Laboratory April 30 & May 1, 1996 Tissue Analysisin Rollo, Missouri

U.S. Geological Survey’s August 22 & 23, 1995 Sediment AnalysisGeologic Division Laboratoryin Denver, Colorado

Block Environmental Services May 20, 1997 Toxicity AnalysisLaboratory in Walnut Creek,California

Quanterra Environmental October 10, 1996 Water AnalysisServices Laboratoryin West Sacramento, California

133


Type of data & field logbooks Validation GroupSediment data from USBR USBR QA staff

Water data from CVRWQCB USBR QA staff

Biota data from USFWS USBR QA staff

Toxicity data from BES USBR QA staff

Field logbooks from USBR’s sampling group USBR QA staff

Sample Collection System Audits

Various groups listed below performed system audits ofvarious sample collection groups:

All of the sampling protocols reviewed were satisfactoryexcept the sampling group from Panoche Water District.The system audit revealed the sampling personnel haddeviated from the sampling protocol specified in theGrassland Bypass Project Sampling Plan. TheCVRWQCB followed up this audit by demonstratingproper sampling procedures and reinforcing the need toadhere to protocols.

Data Validation Activities

Routine data validation was performed to ensure dataquality as stated in the QAPP and activities listed below:

These audits and reviews were conducted to confirm thatparticipating agencies are following their protocols andmeeting the data quality objectives as define in the QAPP.

Sample Collection Group Date(s) Auditing Group(s)USBR sediment sampling June 10–11, 1997 & USFWS, QAQCOM,group June 3–4, 1998 and USBR QA staff

BES’s water sampling group May 13, 1997 USBR QA staff

USBR’s flow measurement January 31, QAQCOMmethodology February 5,6,19,20

& March 4,5,13,14, 1997

CVRWQCB’s water April 9, 1998 QAQCOM &sampling group USBR QA staff

Panoche Water District August 12, 1998 CVRWQCBsampling group

USFWS’s biota sampling June 18, 1998 CDFGgroup

CDFG’s biota sampling June 18, 1998 USFWSgroup

Data Validation MethodsOne of the QAQCOM’s roles is to ensure that theanalytical results have been properly validated and whereproblems have been identified, that the agency and itsrespective laboratory have taken appropriate correctiveactions. Data validation protocols were reviewed byUSBR QA staff.

The validity of the analytical results was assessedby comparing the QC results to the acceptance criteriaidentified in Table 9 of the QAPP. The guidelinesaddress both internal and external QC check sampleresults. Internal QC samples are defined by USBR asthose check samples incorporated by the laboratoriesperforming the work. External QC check samples arethose QC check samples submitted to the laboratories bythe contracting agency.

Numbers and types of external QC check samples,incorporated into each batch of field samples before theyare submitted to the laboratory, were examined. The QCcheck samples were assessed in terms of frequency ofincorporation and appropriateness of the concentrationsof the various chemical parameters of interest. Theresults of the external and internal check samples wereevaluated in terms of their acceptance to meet accuracy,precision, and level of contamination criteria.

Reviewing data packages to identify outliers wasanother step in the validation process performed byUSBR QA staff. Once a data point was identified as apossible outlier, the sample was promptly submitted tothe laboratory for re-analysis. For example, two sedimentselenium results for monitoring Site A collected onMarch 3, 1998 were determined to be outliers. This sitehad been sampled six times from November 1996through September 1998 with the following results: 62,4.2, 56, 150, 12, and 23 µg/g respectively for the 3–8 cmdepth and 55, 5.4, 50, 98, 7.0, and 52 µg/g for the wholecore as shown in the Table 1. After the data results 150

Site A 0–3 cm 3–8 cm Whole Core

November 12, 1996 22 62 55June 10, 1997 2.9 4.2 5.4September 11, 1997 38 56 50March 3, 1998 18 150 98

June 4, 1998 2.8 12 7.0September 28, 1998 8.5 23 52

Table 1. Grassland Bypass Program

San Luis Drain Sediment Monitoring

Selenium Levels (µg/g, dry weight)


134

QA staff reviewed all field calibration sheetssubmitted by each agency. Special attention was paid toinstrument calibration procedures to determine whetherfield measurement data quality objectives were achieved.

QA Issues of ConcernFor the most part, all the agencies did adhere to theprotocols outlined in the QAPP. The only exceptioninvolved the lack of any externally certified biologicalreference material accompanying the samples at a rate of5%, or at least once per batch, whichever is morefrequent. Upon discussing this issue with the U.S. Fishand Wildlife Service (USFWS) and the CaliforniaDepartment of Fish and Game (CDFG), both agenciesagreed to incorporate the certified reference tissue withthe samples (Table 9, QAPP).

There were some minor problems related to theUSGS GDL testing of sediment samples for seleniumand total organic carbon (TOC). These problems causeda delay in reporting results for the annual sedimentsamples collected on June 3 and 4, 1998 to the DCRT.The problem involved the failure of the analyst to use theproper dilution factor in determining the seleniumconcentration of an external QA check sample. This wasremedied by having the laboratory re-check all theselenium sample results to make sure the dilutioncorrection error was not made for any other samples. TheTOC problem resulted from the laboratory’s failure toadequately grind one of the QA check samples to itsproper particle size. The problem was resolved by havingall the samples within that particular job reground andreanalyzed.

The most significant QA issue in the second yearof the Monitoring Program remains the data compara-bility of SLD selenium concentrations in the bottomsediments from one sampling period to the next. Asdescribed in Chapter 7, the heterogeneity of seleniumconcentrations measured in the bottom sediments makesit difficult to identify trends in the data. The issue ofsediment selenium concentration variability within theSLD has been brought to the attention of the DCRT.

Uncertainty Associatedwith EnvironmentalMeasurementsAs with all quantitative measurements, there is a degreeof uncertainty associated with the values provided. Errorsmay be introduced in the sample collection, as well as in

and 98 µg/g were identified as outliers, the correctiveaction described in the QAPP required confirmation ofthese measurements by reanalysis of the original sample.Such action was taken, and the reanalyzed resultsconfirmed the first values. Although these measurementswill remain in the database, periodically they will bereassessed as additional data points for this particular siteare collected. Once a data point can be statisticallyproven to be an outlier, it will either be flagged as aquestionable measurement or will be removed from thedatabase entirely.

In addition to the assessment of laboratoryperformance, an evaluation of sample collection practices,including sample handling and documentation, was alsoconducted to assess the integrity of samples and compli-ance with DQOs. Each agency’s sampling techniqueswere observed. Sample collection procedures wereevaluated including type of sample containers, preserva-tion of samples, filtration and other sample handlingmethods, and documentation of sample collection.USBR QA staff conducted these field audits, examinedrinseate blank results to assess any possible level ofcontamination introduced during sample collection, andmonitored sample holding times to ensure compliancewith prescribed analytical methodology.

As a means of assessing both laboratory perfor-mance and sample homogenization techniques, USBRstaff collected five duplicate SLD sediment samples andone duplicate Mud Slough (Site D) sediment samplewhich were submitted to the U.S. Geological SurveyGeologic Division Laboratory (USGS GDL) foranalyses. These duplicate sample results providedinformation on both laboratory precision and ability offield personnel to properly homogenize samples. Theresults (Table 2) show that analytical precision was metand that homogenization of the sample material wasachieved.

Site Location Selenium Levels Relative Percent

Difference (RPD)

SLD 17/18A (whole) 75 / 79 µg/g 5.2Site A (whole) 7.0 / 6.6 µg/g 5.1SLD 1/2B (3–8) 68 / 76 µg/g 11Site D (3–8) 1.2 / 1.1 µg/g 8.7SLD 10/11C (3–8) 39 / 39 µg/g 0.0SLD 10/11A (0–3) 18 / 22 µg/g 20

Table 2. Quality Assurance Results

GBP Sediment Monitoring Program

Conducted June 3–4, 1998

Duplicates to Measure Laboratory Precision

135


the laboratory analysis. The data generated by theMonitoring Program must be compared to the DQOs ofthe GBP. In addition, as the level of the parameterapproaches the limit of detection for the particularanalytical method, the level of uncertainty of the resultincreases significantly. The data user should understandthe degree of uncertainty or confidence limits associatedwith the data.

SummaryWith few exceptions, the participating agencies in theMonitoring Program complied with the QAPP byfollowing the established protocols. Adherence to the

QAPP helped ensure the reliability of the data collectedand provided the necessary documentation that supportsthe validity of the measurements. Where exceptions didoccur, USBRs QA staff were able to identify and addressthe issue, thereby ensuring all data met the qualityobjectives of this program.

Representativeness of SLD bottom sedimentsamples due to sediment heterogeneity is an issue underreview. The heterogeneous material makes assessment oftemporal changes in selenium levels difficult, if notimpossible, until a statistically valid trend can be estab-lished. A sub committee will be assembled to review thesampling design and analytical methods for sediments inthe SLD.


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