BOISE, Idaho — Cool snowy weather in Idaho’s mountains in early April has boosted snowpack level across the state, according to state and federal water managers.
The Idaho Water Supply Committee met Friday to discuss what farmers, irrigators, sportsmen and recreation users can expect in Idaho’s rivers and lakes this summer.
The group is made up of experts from NRCS Snow Survey, NOAA National Weather Service, Bureau of Reclamation, Army Corps of Engineers, Idaho Power and the Idaho Department of Water Resources.
Overall, they are seeing pretty good mountain snowpack in Idaho, and that combined with good reservoir storage, should provide solid water supplies as we head into the summer.
The two biggest areas of concern in the state are the Big Lost and Big Wood basins with snowpack only in the mid-70 percent range and reduced water supply and streamflow runoff for those areas. Cool moist weather provided a boost during the first week of April but officials says the temperatures are warming up and drying out, not much heavy precipitation is expected in the coming weeks.
April 1 streamflow runoff projections from NRCS Snow Survey and the NW River Forecast Center call for:
- 100 percent in the Clearwater River Basin and Dworshak Reservoir
- 106 percent on the Snake River at Heise, east of Idaho Falls
- 74 percent in the Boise River Basin
- 67 percent in the Big Lost
- 51 percent in the Big Wood
- 49 percent in the Little Wood
NRCS officials said the snowpack in many parts of Idaho is ripening for the spring melt. Peak snowpack is occurring at this time, and things are expected to decline as the melt begins.
Irrigation season begins on April 15 statewide.
NOAA officials said water year moisture is above-average in McCall and Lewiston.
Meanwhile, the 8-14 day forecast is calling for warmer and drier than normal weather in April.
As for the Boise River, runoff is projected to be 975,000 acre-feet, 77 percent of average. Boise River reservoirs are at 70 percent of capacity.
- Lucky Peak is 65 percent full.
- Arrowrock is 76 percent full.
- Anderson Ranch is 69 percent full.
- Lake Lowell is 80 percent full.
Ryan Hedrick with the Bureau of Reclamation says they are holding back water as much as possible right now to fill the reservoir system. No flood control needed as yet.
Hedrick said irrigators in the Treasure Valley should have a full water supply or close-to-full supply, depending if the Boise River reservoir system fills.
Payette River runoff is projected as 84 percent of normal.
Cascade and Deadwood reservoir are at 101 percent of average. 65 percent of capacity.
Owyhee River reservoir storage is 117 percent of average. It is 85 percent full.