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Basalt Groundwater of the Walla Walla Subbasin
Jen Woody, Hydrogeologist
Oregon Water Resources Department
December 13, 2016
Welcome
• Review Basalt Management Options
• Review Columbia River Basalt Aquifers
• Meeting Goal is to discuss data gaps and how to fill them:
1. Describe upcoming water level measurements plans
2. Propose plans for aquifer testing in 2017
3. Discuss how to read flowmeters and report use
Walla Walla Sub-Basin Groundwater Management Plan
1. Prevent further allocation in alluvial and basalt aquifers in the Walla Walla Sub-Basin (Classification): currently in progress
2. Require basalt water right use measurement and reporting in area of concern (SWMPA): currently in progress
3. Stabilize water levels in basalt aquifers in area of concern (Voluntary Agreements and/or Critical Groundwater Area): decrease use by 2020
Part 1: Basalt Groundwater Review
Hydrogeology is a subset of Geology
Hydrogeologists consider:
– How geology controls groundwater flow systems
– Where water enters the ground
– Where water discharges to the surface
– How geology controls storage capacity
– How geology prevents or allows groundwater flow
– How to monitor and interpret water level data from wells
Groundwater Level Measurements
Groundwater Level Measurements
Increasing Time
2009 2016
Feet below land surface
110
150
Feet above sea level
690
650
Groundwater Level Measurements
Water Level Recorder Data
Manual Measurements
Interpreting Geologic Maps
General concepts: • Oldest rock layers are
on the bottom • Youngest layers on the
top • Erosion removes
materials to expose rocks with a range of ages
• Map represents what is exposed at the surface
Columbia River Basalt Group (CRBG) Overview
• Vents located in Northeastern Oregon, parts of Idaho and Washington
• Total thickness greater than 10,000 feet in some places
• Note Abbreviations: CRB, CRBG
Camp and Ross (2004)
Tolan and Lindsey, 2007
Types of Basalt Flows
1) Flow Top
2) Dense Interior
3) Flow Bottom
Interflow zones (flow top & flow bottoms) can host aquifers
Dense interiors separate aquifers
CRBG Flows Have a Three Part Internal Structure
Flow Top
Dense Interior
Flow Bottom
Flow Top
Dense Interior
Interflow Zone
Flow Bottom
www.cbgwma.org
Recharge depends on internal structure
• Thin, highly permeable interflow zones allow wells to pump at high rates
• Low storage capacity
• Recharge occurs many miles away
• Age of groundwater can be >10,000 years
• Long term use usually results in declines
Basalt Aquifers
CRBG Internal Structure and Water Levels
UMAT 5267
UMAT 4010
Not to Scale
Dense Flow Interior
Interflow Zone
Dense Flow Interior
CRBG Internal Structure and Well Construction
UMAT 4184
UMAT 50516
Not to Scale
Why are water levels and trends similar? Dense Flow Interior
Interflow Zone
Windblown Sediments
Ice Age Flood Sediments
Recent River Sediments
Older Sediments
Basalt Younger than 15.6 Ma
Basalt Older than 15.6 Ma
Walla Walla Subbasin Geology
Located Wells by Aquifer
Subbasin Geology
Fault zone offsets interflow zones: How does this affect groundwater flow?
Faults in Cross-Section
Hutter, 1997
www.cbgwma.org
Faults and Groundwater Flow
Basalt Wells Grouped by Groundwater Elevation
Basalt Wells Grouped by Groundwater Elevation
West Side
Central
North
Total Decline = 100 feet Decline rate = 3-4 feet/year
Groundwater Levels: West Side
Total Decline = 125 feet Decline rate = 3-4 ft/year
Groundwater Levels: Central Valley and East
Average decline = 3 ft/year
Groundwater Levels: North (Washington)
Total Decline = 100 feet Decline rate = 2-8 ft/year
Basalt Groundwater Level Declines
• Declines are occurring in the CRBG aquifers across the Walla Walla Sub-basin at rates ranging up to 4 feet per year.
• The fact that water levels are declining means use exceeds natural recharge.
• Water level data available at: http://www.oregon.gov/owrd/pages/gw/well_data.aspx
Part 2: Current and Future Data Gathering Efforts
Data Gaps and Proposed Activities
• Field location of basalt wells with water rights Presently working on, continue through the winter
• Synoptic water level measurements to assess groups Next complete round week of February 6, 2017
• Water Use Assessment Need flowmeters before this can be fully conducted, but
currently checking data on file for errors
• Which faults or fault zones act as groundwater flow paths? Which act as groundwater flow resistors? Aquifer testing and controlled spring start-up of wells
Updated 2017 Timelines
• January: 2nd Rule Advisory Committee (RAC) meeting • February: Comprehensive water level measurements
• March-April: Aquifer testing, controlled start-up to
better define groupings of hydraulically connected wells
• May: Water Resources Commission meeting: Classification and Serious Water Management Problem Area (SWMPA) Rules
Updated 2017 Timelines
• May-June: WRD Data processing, improve delineation of groups
• July: WRD reports test results back to basalt water users
• September 2017: Deadline to form a work group to develop voluntary agreements
• October 2017: Begin next round of rulemaking regarding water use reductions from basalt aquifers (Critical Groundwater Area and/or Voluntary Agreements)
Part 3: Flowmeters and Water Use Reporting
Flowmeters: Pumping Rate
725 Gallons per Minute 12,345 Gallons per Second
Flowmeters: Totalizer Reading
3255 x 100 Gallons = 325,500 Gallons
12,345,678 Gallons
Flowmeters: Calculating Total Use
325,500 Gallons minus Last reading = Use since last reading
12,345,678 Gallons minus last reading = Use since last reading
Flowmeters: Examples of Common Problems
Meter “rolled over”. If last reading was 800000 x 100 Gal. Total use = rollover value of 100,000,000 – 80,000,000 + 325,500= 20,325,500 Gallons (this is the value to report)
Misread units: should be GPS, recorded GPM
What to record from the Flowmeter
If you record these pieces of information each time you visit the flowmeter, you have what you need to fill out water use reporting forms for OWRD. Don’t forget to do the math described in the previous slide to calculate volume used since last reading.
Water Use Reporting
Stay Involved and Informed
Web page: http://www.oregon.gov/owrd/Pages/Place/Walla_Walla_SubBasin.aspx
Contact: Jen Woody 503-986-0855 or [email protected]
Water use reporting questions: [email protected] and
http://www.oregon.gov/owrd/pages/wr/water_use_report.aspx
Discussion Items for Basalt Water Right Holders
• Aquifer tests: use groups with similar water level elevation • WRD will supply the equipment and labor • Need one well to pump, multiple static wells to monitor
water level changes during and after pumping • Pumped well needs to have flowmeter that reads rate (i.e.
gpm) • Able to pump at least 24 hours • Able to move water away from the well • Pumping well needs valve where constant rate is possible • Pumping and observation wells need to be measurable with
an etape (access port and minimal obstructions between land surface and water level)
• Well ownership clarification/updates