Water Supply Committee reviews mixed picture in Idaho

BOISE, Idaho (KIFI/KIDK) - The Idaho Water Supply Committee learned Friday three water basins are well below average snowpack this winter. In fact, the Big Wood Basin could set a record low for water year precipitation. One snow site north of Ketchum recorded just .3 inch of snow.

With less than an inch of measurable precipitation during February, The Big Wood, Little Wood and Big Lost basins are areas of concern, with 56-61% of normal snowpack.

Streamflow runoff predictions are currently estimated at 49% above Hailey, 60% in the Big Lost, and 42% in the Little Wood, which could leave those areas with irrigation shortages this summer.

There is some hope with forecasts calling for snow this weekend, next week and through the 30-day outlook.

The picture is much brighter in the Upper Snake region.

Reservoir storage is 3.645 million acre-feet, which is 90% of capacity and possibly a new record for reservoir storage as of March 1. Bureau of Reclamation spokesman Jeremy Dalling told the committee the reservoir storage is 900,000 acre-feet above average.

"We have very good storage levels in the Upper Snake – that's good news for water users and irrigators," he said.

The Upper Snake reservoir system is expected to fill. Dalling said streamflow runoff is projected to be 102% of normal for the South Fork at Heise, 95% in the Henry's Fork and Island Park Reservoir, 96% in the Teton basin, 90% in Ririe, and 46% in the Little Wood.

Flood control releases have already begun in the Upper Snake, with flows around 3,600 cubic feet per second (CFS) at Palisades.

American Falls Reservoir and Minidoka are running between 4,750 to 4,850 CFS. Most of that water is going to recharge of the Eastern Snake Plain Aquifer below Milner Dam.