Idaho Water Resources begins study to identify managed groundwater recharge sites

November 1997

U.S. Water News Online

BOISE, Idaho -- State water managers have launched a comprehensive two-year technical study to pinpoint at least five sites on the Eastern Snake Plain Aquifer (ESPA) that could be used to recharge hundreds of billions of gallons of water back into the ground to help combat declining groundwater levels and spring flows, the Idaho Department of Water Resources has announced.

The managed aquifer recharge study is designed to ascertain just how feasible large-scale managed recharge may be and evaluate its potential value in helping protect the long-term availability of water resources in the Eastern Snake River Plain, according to Idaho Department of Water Resources (IDWR) program managers.

A major goal of the study is to identify and evaluate at least five geographic locations on the ESPA that can recharge up to 500,000 acre feet of water annually back into the aquifer. Preliminary design plans will be prepared for each site.

Declines in spring flows and groundwater levels have evolved over the years as a result of increases in groundwater pumping coupled with reduced incidental recharge due to increased efficiency in irrigation practices. About 800,000 acres of land irrigated by groundwater have been brought into production on the Eastern Snake Plain since the 1950s.

Groundwater levels measured in 1996 were compared to groundwater levels measured in 1980. The results show declines of up to 10 feet or more in nearly all areas of the 10,000 square-mile aquifer.

The project is being directed by IDWR in collaboration with the U.S. Bureau of Reclamation. It is designed to evaluate managed recharge from the hydrologic, environmental, economic and institutional perspectives.

Part One of the study will look at the hydrologic feasibility of managed recharge on such a large scale. This phase will address three key points:

  • The availability of recharge water in Snake River reaches above Milner Dam.

  • The impact of managed recharge on groundwater levels and spring discharge to the Snake River.

  • The impact of managed recharge on seasonal augmentation of Snake River return flows.

  • Part Two will focus on institutional, economic, and environmental feasibility issues. Key points to be addressed include:

  • Water rights for managed recharge, including changes in points of diversion and nature of use, injury mitigation, and crediting of benefits. Winter water savings and uncertainty and risk in refilling of reservoir storage space.

  • Cost of constructing new conveyance and recharge facilities to meet targeted recharge objectives.

  • Environmental and water quality issues including NEPA, Clean Water Act, and Endangered Species Act processes.

  • A broad outcome of the study also is to determine just how managed aquifer recharge projects can be used to help control the timing, location, and quantity of recharge in the ESPA. Water managers say that approach can make managed aquifer recharge an important part of a comprehensive water resource management plan for the Eastern Snake River Plain.



    Return to the U.S. Water News Archives page

    Or

    Return to the U.S. Water News Homepage


    uswatrnews@aol.com