Organic Carbon and Urban Sources - Organic Carbon and Urban Sources - What Do We Know?What Do We Know?

Michael Zanoli Department of Water Resources,

Division of Environmental Services, MWQI Program

CBDA OC Conceptual Model Workgroup CBDA OC Conceptual Model Workgroup January 18, 2005January 18, 2005

What Do We Know About Urban OC Sources?

Increasing Delta-wide due to high growth rates

Difficult to monitor and evaluate impacts (NPS effect)

Potential impacts depend on hydrology, time, and proximity to intakes (as with other sources)

Basic metrics such as yields and reactivity appear comparable to current values for rivers, channels (Sac, SJR, Twitchell Is) ??

Number of Days TOC Load Contributions to theSacramento River were at or above 5%, 10%, and 20%

Load Contribution

_5% 10% 20%

NEMDC 124 36 17 __________________________________________

Daily NEMDC Contribution to Total Sacramento River TOC Load

July 2001 - June 2004

n = 1080

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

55%

60%

Min

Max

Ave

n = 1080

Yields (gC/m2/yr)

NEMDC = 3-6

Arcade Creek = 12 (USGS 2003)

Temperate zones = 1-8 (Thurman)

Reactivity (mmol THM/mol C)

NEMDC = 6 -12 (median)

Twitchell Is drains, channels = 2-16 (USGS)

Rivers = 4-16.5 (USGS)

Other OC Metrics

Lessons Learned from an Urban Drain (2001-04)

Natomas East Main Drainage Canal (NEMDC) discharge can contribute substantial TOC loads to Sacramento River during storm events, especially in late summer/initial fall storms

Data suggest cumulative discharges from urban sources in high-growth areas in the Delta and tributaries could be significant TOC loading sources for DW intakes during these storm events

With current and projected growth (>60%), potential impacts from urban runoff into the Delta will significantly increase within lifetime of CALFED program

1. Data about physical and chemical processes affecting carbon release from different land uses in urban watersheds.

2. Knowing how changing land and water management practices affect TOC and DBP concentrations and loads? Source: adapted from Deverell pers. comm. 1/6/05

3. Data on other urban sources (Stockton, Tracy, etc.), esp tributary hydrology - e.g. SacR vs SJR. (timing & flow determines potential impact).

4. How much of urban OC gets to DW intakes and what fraction forms DBPs?

What We Don’t Know About Urban OC Sources(Info Needed for Conceptual Model)

DOC Yields Sacramento River Basin

1. Yield < 5 Mg/km2

– 1 Sacramento River at Bend Bridge– 2 Sacramento River at Colusa– 9 American River at Sacramento

2. Yield 5-10 Mg/km2– 6 Colusa Basin Drain– 8 Arcade Creek– 4 Feather River (including site 3, the Yuba River)

3. Yield 10 Mg/km2– 5 Sacramento Slough– 10 Sacramento River Sites near Freeport

Source: Saleh, et al,. 2003

Summary of Highest Daily NEMDC TOC Loads to the Sacramento River

0100000200000300000400000500000600000700000800000900000

10000001100000120000013000001400000150000016000001700000180000019000002000000

Load

(lbs

/day

)

0%

5%

10%

15%

20%

25%

% o

f TO

C Lo

ad

Sac R

NEMDC

NEMDC% Load

Error Estimation!Error Estimation!(The Elephant on the Table)(The Elephant on the Table)

TOC/DOC Concentration TOC/DOC Concentration

- Drives yields - Drives yields (TOC, DOC)(TOC, DOC), reactivity , reactivity (DOC)(DOC)

- Real TOC/DOC value? Depends on:- Real TOC/DOC value? Depends on:• Rep sampling/field VariabilityRep sampling/field Variability• Lab error (commonly +Lab error (commonly +-- 30% ) 30% )• Methods = comb vs wet oxMethods = comb vs wet ox

FlowsFlows

- Stage measurements- Stage measurements

- Rating table- Rating table

- Sensor error- Sensor error

Load EstimatesLoad Estimates

Implications of Global Climate ChangeImplications of Global Climate Change More water earlier in season, More water earlier in season,

increased intensity = more runoff in increased intensity = more runoff in shorter period.shorter period.

Salinity increase from sea level rise + Salinity increase from sea level rise + levee instability = less Delta use levee instability = less Delta use possible?possible?

SacR becomes more important in SacR becomes more important in future, esp if PC built because Delta future, esp if PC built because Delta not used for conveyance (no peat not used for conveyance (no peat issues).issues).

Growth along I-5 and urban inputs to Growth along I-5 and urban inputs to SacR could increase impacts.SacR could increase impacts.

Urban OC Load NightmareUrban OC Load Nightmare Imagine 20 yrs in future – a combination drought and storm pattern Imagine 20 yrs in future – a combination drought and storm pattern

change has resulted in low river flows, low reservoir levels, and change has resulted in low river flows, low reservoir levels, and more water coming in a much shorter period.more water coming in a much shorter period.

Freak storms from above increaseFreak storms from above increase The economy is slow – less logging and construction so usual nps The economy is slow – less logging and construction so usual nps

oc loads in SacR are lower/stable.oc loads in SacR are lower/stable. But urban growth has continued, even if slowed a bitBut urban growth has continued, even if slowed a bit Ag drainage lower/stable because less water + land conversionAg drainage lower/stable because less water + land conversion RESULT ?RESULT ? Urban source dominate river oc loads during many more storms!Urban source dominate river oc loads during many more storms!

Current ChallengesCurrent Challenges

Hard to Get Data on Loading-no Hard to Get Data on Loading-no BaselineBaseline

No Regulatory Hook to Require No Regulatory Hook to Require MonitoringMonitoring

Efforts to Work With the CVRWQCB Efforts to Work With the CVRWQCB Have Been DisappointingHave Been Disappointing

Urban Discharge GrowingUrban Discharge Growing

Assess Sources and LoadsAssess Sources and Loads

Monitoring Station NeedsMonitoring Station Needs LocationLocation ParametersParameters

Regulatory PurposesRegulatory Purposes Cumulative Discharges- Basin PlanCumulative Discharges- Basin Plan EIR/EIS Impact SignificanceEIR/EIS Impact Significance

Provide Priorities for Watershed Provide Priorities for Watershed Protection ProjectsProtection Projects

Assess Sources and LoadsAssess Sources and Loads

Model Transport of Contaminants Model Transport of Contaminants From Different SourcesFrom Different Sources

Determine Priority Sources for Determine Priority Sources for Watershed Protection EffortsWatershed Protection Efforts

Apply Information to Regulatory Apply Information to Regulatory Processes or Control EffortsProcesses or Control Efforts

Assess Sources and LoadsAssess Sources and Loads

Loading Information From Loading Information From Various Land UsesVarious Land Uses

Determine Sampling Locations to Determine Sampling Locations to Fill in the GapsFill in the Gaps

Model Development for Transport Model Development for Transport and Load at Intakes.and Load at Intakes.

Future Model UsesFuture Model Uses

Early Warning (Real Time forecasting) Early Warning (Real Time forecasting) Planning Tool for Future Impacts (long term Planning Tool for Future Impacts (long term

forecasting) forecasting) Assess Sources and LoadsAssess Sources and Loads

Monitoring and station location needsMonitoring and station location needs Regulatory purposes ( TMDLs)Regulatory purposes ( TMDLs) Provide priorities for watershed protection projects Provide priorities for watershed protection projects

Contamination Scenarios for Emergency Contamination Scenarios for Emergency PreparednessPreparedness