Idaho's Eastern Snake Plain Aquifer Managed Aquifer Recharge Program

Abstract

Abstract The Eastern Snake Plain Aquifer (ESPA), Idaho's largest and most productive aquifer, has experienced substantial decline since the early 1950s due to changing climate conditions, increased demands, and evolving irrigation practices. To address this issue, the Idaho Water Resource Board (IWRB) developed the ESPA Comprehensive Aquifer Management Plan (CAMP). The CAMP outlines methods and goals for the replenishment of the aquifer, including the development of a managed aquifer recharge (MAR) program. In 2014, the State of Idaho has provided dedicated, long‐term funding for the MAR with the goal of achieving an average annual recharge rate of 0.3084 km 3 (250,000 ac/ft). Since then, the IWRB has invested over $16 million dollars in investigations and infrastructure improvements to support MAR operations and program build‐out, resulting in an addition of over 62.3 m 3 /s (2,200 cfs) of instantaneous MAR capacity and total programmatic recharge of over 2.2203 km 3 (1.8 million acre‐feet). Overall, the program has added an average of 0.3207 km 3 (260,000 ac/ft) per year to the aquifer. Utilizing existing infrastructure and the IWRB's natural flow water rights has significantly reduced programmatic costs. The program's cost for conducting MAR since 2014 is $0.01 per cubic meter or $18 per acre‐foot accounting for capital cost, conveyance fees, operation and maintenance, and monitoring cost. Future capacity increases are planned to further assist the program in capturing excess water when it is available.