Statewide Aquifer Conditions Presented to The Association of Idaho Cities By Ken Neely October 25, 2016 IDWR’s Mission: • To serve the citizens of Idaho by ensuring that water is conserved and available for the sustainability of Idaho’s economy, ecosystems, and resulting quality of life. Two of IDWR’s Goals are: • Protect senior water rights. • Promote full economic development of the water resources of Idaho Three Overarching Objectives: • Conjunctive administration of SW and GW. • Additional SW and GW storage capacity. • Reduce timeframe for water rights. Idaho Ground Water Monitoring • IDWR monitors over 900 wells. • Monitoring is accomplished by Electric Tapes and Data Transducers. • Monitoring frequencies vary. • Data is stored at IDWR and is available to the public through our website. Electric tapes Data Transducers Idaho Aquifer Systems Today, we’ll look at: 1. Aquifers systems in N Idaho 2. Aquifer systems in SW Idaho 3. Aquifer systems N and S of the Eastern Snake Plain 4. Eastern Snake Plain Aquifer Hydrographs Rathdrum Prairie Aquifer Rathdrum Prairie Hydrographs 30 wells monitored, all with transducers Palouse Basin Aquifer Palouse Basin Hydrographs Wanapum 3 wells monitored Grande Ronde Lewiston Basin Lewiston Hydrographs Saddle Mountains Grande Ronde Regional Grande Ronde Upper Wanapum 39 wells monitored Lewiston Basin • 3 basalt aquifer systems with clay interbeds • Previous GWMA (1994) for Saddle Mountains • New GWMA (2013) for Wanapum • Current status: Saddle Mts is stable; Wanapum is declining; Grande Ronde is stable, but under new developments Summary for Northern Idaho • 3 major water basins: Rathdrum Prairie, Palouse, and Lewiston • Rathdrum Prairie has stable water level trends, but has surface water and ground water interaction issues •Palouse and Lewiston have declining trends • All 3 systems have interstate aspects • Idaho adjudication to protect our water rights Treasure Valley Treasure Valley Summary for Treasure Valley • Complex hydrogeology: cold H2O & geothermal • 2 management areas • Some areas are stable; some areas declining • Model development in the next couple years to understand water supply • New Area of Drilling Concern creates rules to protect water quality Mountain Home 26 wells monitored Mountain Home • Basalt and sedimentary aquifers • Cinder Cone Butte CGWA (1981) • Mountain Home GWMA(1982) • Stable water levels in NE; declining in SW Summary for Mountain Home & Bruneau-Grand View • Mountain Home Issues. Uncertainty as to ground water availability for current and future demands (Air Force Base, municipal, residential, and agriculture). • Mountain Home Efforts: Technical studies, recharge, water budgets, water district. • In Bruneau-Grand View, the average decline from 2000-2010 is 0.76 ft per year. Endangered species. Very limited water supply. Big Wood Valley Big Wood Hydrographs •35 wells monitored in Big Wood Valley Big Wood Valley • GWMA (1991) • SW/GW connection in the north – stable WLs • Ground water is confined in the south – declining WLs • Recent Model Development • Recent call on water related to declining ESPA aquifer (call has been stayed) Big Lost River Valley Big Lost Hydrographs • 23 wells monitored Big Lost • Ground water flows from NW to SE • SW/GW connection • Declining levels below Mackay • Tributary to ESPA Bear River Valley Bear River Hydrographs Summary of Bear River Alluvial aquifer system Unique multi-state flow paths GWMA (2001) Some declines; some stable Ground Water Management Areas (GWMA) Critical Ground Water Areas (CGWA) Basins in south central Idaho – south of the Snake River Raft River Valley Raft River Hydrographs 21 wells Monitored Raft River Valley • CGWA designated in 1963 • Ground water flows from south to north • GW pumping is primary source of irrigation water. • Long-term (50 yrs) declining water levels Eastern Snake Plain Aquifer (ESPA) ESPA Hydrographs Water Level Change - Spring 1980 to Spring 2008 With Well Locations with Well Locations Water Level Change (ft) 30 25 20 15 10 -5,800,000 AF 5 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 541 wells Summary of ESPA • Aquifer composed primarily of basalt • Declining ground water levels and loss of storage • Conflicts between surface water users and ground water users • Primary effort is “aquifer stabilization” through “managed recharge” efforts Conclusions • IDWR maintains a GW monitoring network. • Many basins have water level declines. • Continue analyzing data throughout the state, and use results to manage the resources. • Efforts are under way for Aquifer Stabilization. It all starts here.