Eastern and southern Idaho water users are being advised to plan and operate under conservative plans in order to stretch this year’s water supplies.
The Natural Resources Conservation Service Idaho Water Supply Outlook indicates water year precipitation is about 75 percent of average in the Henry’s Fork basin and about 85 percent of average for the Snake River above Palisades Reservoir.
According to the report, lower elevation snowpack in eastern Idaho saw a major decrease in snow water content during March, when most measuring sites should have seen increases. Snowpack in the Willow, Blackfoot and Portneuf river basins are only 30 percent of average.
Snake River streamflow near Heise is forecast at 72 percent of average. Combined with current storage levels, that amount of water will barely exceed the amount needed for adequate surface irrigation supplies.
If weather remains warm and dry, it could make water supplies even tighter. Due to early irrigation demand exceeding natural streamflow levels, NRCS warned it may be a challenge to fill some reservoirs.