Amid Dry, Warm Spring, Southern Idaho May Need to Tap Into Water Reservoirs

BOISE, ID – Southern Idaho’s water reservoirs are stocked up, signaling promise for this year’s irrigation prospects.

But Idaho might need to rely on reservoirs more than usual this year, amid drier and warmer early spring months that have prompted faster snow melts with less streamflow runoff than expected, the Idaho Water Supply Committee heard from state water officials at its Tuesday meeting.

“My prediction is it’s gonna be a summer where we really dip into our reservoir system,” said Idaho Department of Water Resources Hydrologist David Hoekema, who chairs the committee.

About a quarter of the state is in moderate drought currently, he said, but officials might be underestimating drought conditions in some places.

Here’s how Idaho reservoir systems are fairing:

  • The Owyhee River reservoir system is full.
  • Two other reservoir systems – along the Boise and Payette rivers – are expected to fill to 100%.
  • Officials expect the Upper Snake reservoir system to fill, or nearly fill, and it is now 88% full.
  • In eastern Idaho, the Henrys Fork system is 99% full, the Island Park Reservoir is 100% full, the Ririe Reservoir is 100% full and the American Falls Reservoir is 96% full.

Erin Whorton, a water supply specialist with the National Resources Conservation Service, said North Idaho’s mountain snowpack and runoff is in better shape than this time last year, when the region had one of its lowest snowpacks on record, the Idaho Capital Sun previously reported.

The Idaho Water Supply Committee is planning to meet again in early November.

Idaho’s Upper Snake River reservoir system is at 88% of capacity as of May 19, 2025. Average daily streamflows are indicated in cubic feet per second. (Courtesy of the Bureau of Land Management)
Idaho’s Upper Snake River reservoir system is at 88% of capacity as of May 19, 2025. Average daily streamflows are indicated in cubic feet per second. (Courtesy of the Bureau of Land Management)

 

Idaho Capital Sun is part of States Newsroom, a nonprofit news network supported by grants and a coalition of donors as a 501c(3) public charity. Idaho Capital Sun maintains editorial independence. Contact Editor Christina Lords for questions: info@idahocapitalsun.com.

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