Irrigation Challenges On The Horizon For Southern Idaho Growers

Senior Snake River users in Idaho could face a significant shortfall this irrigation season.  Mathew Weaver, director of the Idaho Department of Water Resources, issued an order Friday estimating a deficit of 181,600 acre-feet for 2026.  The finding comes from the state’s annual methodology review, which evaluates river flows, aquifer conditions, and irrigation demand. 

Under Idaho’s “first in time, first in right” water law, senior surface water users take priority over junior groundwater users drawing from the Eastern Snake Plain Aquifer.  The order requires many junior groundwater users—those with rights dated after October 1900—to secure approved mitigation plans by May 1st or risk curtailment.

The largest projected impacts fall on the American Falls Reservoir District Number Two and the Twin Falls Canal Company.

State officials say the shortfall is tied to below-average river flows, forecast at just 70% of normal for the spring and early summer.

An updated order is expected in July.

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