Idaho's Eastern Snake Plain Aquifer: cooperative water policy change for Idaho's groundwater farmers

Abstract

Abstract In 2015, the state of Idaho finalized a cooperative five-year agreement between ground- and surface-water farmers in Idaho's Eastern Snake Plain Aquifer (ESPA). The agreement, which was the result of multi-decadal legal, regulatory, and policy disputes, stipulated a reduction in groundwater withdrawals for the purpose of replenishing the overdrawn aquifer. The state was constrained by its legacy water allocation doctrine called prior appropriation - a framework for water law informally referred to as ‘first-in-time, first-in-right' that prioritizes seniority when water rights are contested - becoming particularly fraught with the social-ecological balance shift over time due to in-migration, multi-year drought, and more, leading to a mismatch between supply and demand. The two primary components of the five-year water reduction agreement used a tiered system of usage reductions from 4-20%, with an average of about 13% per groundwater farmer. The requirement also required all farmers to put in water meters on all irrigable land at their own expense. These activities were administered by managers in the eight groundwater districts impacted by the agreement and were reacted to by individual farmers with everything from reluctant acceptance to threats of lawsuits. Impact-wise, our research found farmers' net yields and farm income decreased by around 8% during the first two years of the agreement, but also that by 2020, when the agreement ended, the state’s aquifer level measurements actually surpassed the initial goal of adding 2 million acre-feet (∼2.47 trillion m3) to the aquifer by about 200 000 acre-feet (∼246 696 000 m3).