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 Jennifer.L.Woody@oregon.gov

Water use reporting questions: wateruse@wrd.state.or.us 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