Water-level monitoring and a groundwater model in the Big Wood River Valley

Presented by Mike McVay November 5, 2012

IDWR Data Logger Network

• 13 wells have been instrumented; 5 candidates for future deployment.

• Data loggers are collecting water level readings two times per day.

• Downloaded every six months.

Water level trends 1980’s - current

Upper Wood River WMD Well Network

•36 wells have been identified as monitoring locations.

•Semi-annual measurements are proposed for the monitoring frequency.

USGS Synoptic

Network

Over 90 wells were measured in 2006 and re-measured in October 2012.

Ground Water Model of the

Big Wood Valley • Collaboration with

the USGS.• 2006 synoptic

water levels show ground water flow is from north to south.

Why a Model of the Big Wood?• Fully allocated resource– Designated GWMA in 1991

• Water rights distribution problem– Most proposed transfers involve up-basin movement of

PODs• Conjunctive administration/management on its

way– Delivery calls imminent (Big Wood Canal Company)– 2009 petition for CGWA– Measurement district created in 2011

Why a Model of the Big Wood (cont’d)

• IDWR needs unbiased, public domain groundwater flow model to evaluate transfers and mitigation requirements

• Timing good because USGS study nearing completion– Synoptic water level measurement and trend

analysis in 2006– Water Budget report in 2009– Hydrogeologic Framework report in 2012

The Model• A three-year timeframe• IDWR collaborating with USGS to develop groundwater

flow model with oversight from Technical Advisory Committee

• Water Board financing with USGS match • Used for administration of water– Evaluation of Transfers– Determine Curtailment– Evaluate Mitigation– Won’t be used to determine injury

Technical Advisory Committee• Provides transparency and is a vehicle for stakeholder

input• Likely participants:– Previous USGS Cooperators

• Cities of Bellevue, Hailey, Ketchum, Sun Valley• Nature Conservancy• Blaine Soil Conservation District• Citizens for Smart Growth• Sun Valley Water and Sewer

– Big Wood Canal Company– Water District 37?– Technical representatives for others

Summary of Work Plan• Additional data collection

– Water level synoptic in October 2012– Streamflow gain/loss surveys in August and October 2012 and

March 2013– Additional wells

• Form Technical Advisory Committee• Construct and calibrate groundwater flow model

– Update water budget– Model discretization– Initial parameterization– Calibration

• Convert Steady State model to transient model

Activities to Date• Sponsored 4 new USGS gages in 2010 (North Fork,

East Fork, Trail Creek, Warm Springs)• Expanded monitoring well network from 6 wells to

18• USGS seepage analysis to quantify reach

gains/losses• Synoptic water level measurement in 2012• Developed modeling work plan w/ budget and

schedule

Products• Numerical groundwater flow model• Final Report describing model and development• Reports describing results of scenarios– Drought– Change in land use– Climate change

• USGS Fact Sheet• Response function maps

Questions?