Pocatello – Based on mountain snowpack levels, 2025 should be a pretty decent water year for Idaho irrigators.
That’s great news for farmers, and recreationists, who depend on the state’s reservoirs to provide water during Idaho’s hot, dry summer months.
As of March 20, snowpack levels in most Idaho basins were well above normal, and the amount of carryover water in Idaho reservoirs was close to normal.
“Based on the snowpack … it looks good,” Idaho Water Users Association Executive Director Paul Arrington said about the state’s 2025 water supply outlook.
“The snowpack is looking pretty good,” said Craig Chandler, the watermaster for Water District 1, Idaho’s largest and most important water district, which encompasses the upper Snake River system.
The upper Snake reservoir system can hold 4.1 million acre-feet of water, enough to supply well over 1 million acres of farmland in eastern and southern Idaho with irrigation water.
As of March 20, the upper Snake reservoir system was 81 percent full and had about 300,000 acre-feet more water than average.
“Things are shaping up to be a decent water year,” Chandler said.
Snowpack in the Boise basin was 120 percent of average on March 20.
“All of our reservoirs should fill this year,” said Bob Carter, project manager for the Boise Project Board of Control, which provides water to five irrigation districts that service a total of 165,000 acres of irrigated ground in the Treasure Valley of southwestern Idaho.
That said, he added, how the water supply year ultimately turns out could have a lot to do with how the snow melts off and how much actually makes it into the reservoirs.
“If it comes off nice and mellow … we should have a really good water season,” Carter said. “It all depends now on how that snow melts off. That’s Mother Nature’s call.”
Arrington agreed with that viewpoint.
From a snowpack standpoint, things look good, he said. But he pointed out that a few years back, snowpack levels also looked good, but snowmelt and runoff weren’t ideal and a lot of water didn’t make it to the river.
“We’re optimistic,” Arrington said. “Things look good, but that doesn’t mean we can relax. There are multiple elements to our water supply. Snowpack is one part of the story and that story looks good right now.”
Peak snowpack in Idaho basins typically occurs around the first part of April.
As of March 20, most basins in Idaho had more than 100 percent of average snowpack. The upper Snake above Palisades was sitting at 109 percent of average and the upper Snake above American Falls was also at 109 percent.
Snowpack in the Weiser basin was at 138 percent of normal and it was at 132 percent in the Payette basin and 124 percent in the Boise basin.
Other basins as of March 20: Owyhee (135 percent), Bear River (113 percent), Portneuf-Blackfoot-Willow (130 percent), Salmon (117), Big Wood (116), Little Wood (104), Big Lost (107), Little Lost (97).
The Northern Panhandle (96 percent), Coeur d’Alene (88) and Clearwater (97) basins were below 100 percent of average, but the 5-day forecast as of March 20 favored more precipitation.
“We’re coming into a wet period, especially in North Idaho,” Erin Whorton, a water supply specialist with the NRCS, said during a March 20 water supply meeting.