IDWR Methodology Order Predicts 162,600 Acre-Foot Water Shortfall For Snake River

Junior ground water users face curtailment by May 20

Published online: May 10, 2022 Articles
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Boise, Idaho – The Director of the Idaho Department of Water Resources (IDWR) has issued a methodology order for Snake River ground water users, predicting a 162,600 acre-foot shortfall to senior priority water users in the Eastern Snake River Plain (ESPA) region in the 2022 irrigation season.

The shortfall prediction means that IDWR will curtail more than 328 ground water rights with priority dates junior to Dec. 25, 1979 in the coming weeks if the holders of those water rights do not come into compliance with an approved mitigation plan with a ground water district.

Curtailment will begin on May 20, according to the order, unless ground water users have joined an approved mitigation plan prior to that time.

Currently, there are seven approved mitigation plans for the ESPA surface water delivery call. The approved plans came from the Idaho Ground Water Appropriators, Inc. (IGWA), Southwest Irrigation District, Goose Creek Irrigation District, Coalition of Cities and Water Mitigation Coalition. Those entities will not need to show how they can mitigate for projected water shortfalls, the Director’s order said.

The Department’s injury determination will be update in July. Junior water users who could be affected by the order were sent a copy of the order this week.

“By law, we have to keep people with senior water rights whole, and we want to make the junior ground water pumpers aware that despite the settlement agreements between the Surface Water Coalition, IGWA and the Participating Cities, if junior ground water pumpers are not participating in an approved mitigation plan, they could be subject to curtailment this year,” Mathew Weaver, Deputy Director of IDWR, said.

Much water litigation has resulted over conflicts between Snake River surface water users who have senior water rights under the basic principal of Idaho water law—first in time, first in right—and ground water users with junior water rights in the ESPA. Consequently, the Director of IDWR is required to issue an order at the beginning of the irrigation season, and then again in early July, determining any shortfall in water supply to the senior surface water right holders, and determining the obligation of junior ground water pumpers to curtail water use or mitigate for depletions to the holders of senior priority water rights.

Ground water users who have joined an approved mitigation plan will avoid curtailment this year and in the future, and they will avoid future large-scale litigation issues related to water use in the ESPA area that could affect cities, commerce, industry, agriculture and the Southern Idaho economy, officials said.

If junior ground water users do not join a ground water mitigation plan or demonstrate to the Director how their water use will not cause injury to senior surface water users in the next 14 days, their water rights will be curtailed, the order said.