Report: Idaho’s water supply forecast looks promising

Posted at 2:25 PM, Apr 08, 2020
and last updated 2020-04-08 16:28:16-04

BOISE, Idaho — Idaho runoff is expected to be approximately 80 to 120 percent of normal, according to the Natural Resources Conservation Service’s April Water Supply Outlook Report for the 2020 water year. The report was released Wednesday.

Although most of Idaho received below-normal precipitation during March, two storms at the end of the month brought one to three inches of much-needed precipitation to central Idaho, the report pointed out. Nearly all of Idaho received some precipitation from these storms, with lesser amounts in the far southwest corner of the state.

“Even with below-normal precipitation in March, slight snowpack improvements were observed across most of Idaho since March 1,” said Daniel Tappa, Supervisory Hydrologist with the Idaho Natural Resources Conservation Service. “While this seems paradoxical, it implies that little snowmelt occurred and the precipitation that we did receive came in the form of snow.”

Streamflow forecasts have changed little since last month, experts say, and for the majority of Idaho runoff is expected to be approximately 80 to 120 percent of normal. The main areas of concern continue to be centered in the Wood and Lost basins, in the in Sun Valley area, where median streamflow forecasts range from approximately 20 to 60 percent of normal.

“Reservoir storage for the Boise Basin is above normal for April 1. Boise system storage (for the Anderson Ranch, Arrowrock, and Lucky Peak Dams) is at 70 percent capacity, with streamflow forecasts ranging from 60 to 90 percent,” said Six On Your Side’s Chief Meteorologist Scott Dorval.

“With above-normal reservoir storage and slightly lower than normal streamflow forecasts, most Boise and West Central Idaho water users should expect an adequate water supply for the runoff period,” he added.

For information on specific basins, streams, and reservoirs, you can check out the full April Water Supply Outlook Report on-line at the NRCS website.