Late winter, early spring snow brought Idaho water supply to normal levels

Idaho’s water supply is sufficient, with parts of North Idaho being the exception, according to state water experts. 

In an Idaho Water Supply Committee meeting Friday, water experts discussed Idaho’s water supply levels, highlighting that while most parts of Idaho started out the winter with weak snowfall and rain, snow in March and early April across southern Idaho brought many basins closer to normal snowpack conditions. 

With the snow melting and rivers rising, irrigation supplies for farming and ranching are expected to be sufficient in southern Idaho. In places like Owyhee County, the water supply is better than average, and there is a supply for the next two years. 

Erin Whorton, a water supply specialist at the Natural Resources Conservation Service, said during the meeting that wet spring conditions helped bring up water supply levels to normal, especially in the southern part of the state.

“We have been either near normal or above normal for reservoir storage this year, so that is a really good part of the water supply picture,” Whorton said.

But exceptions to normal reservoir levels include Mackay Reservoir, Brownlee and Lake Pend Oreille, according to the Idaho Water Supply Outlook Report.

The report also shows data from the NOAA’s Climate Prediction Center, which predicts spring and summer will be warmer and drier than normal, which could impact water supply by increasing irrigation demand, changing the timing and duration of irrigation, and impacting streamflow volumes. 

Grant Bell, with the U.S. Corps of Engineers, said his team started flood risk management releases in the Boise River in late March. 

This week, he said his team will release water from Lucky Peak Reservoir at a rate of 4,000 cubic feet per second, and they might increase the water flow if conditions get really wet.

“Many places are making releases and many places are quite full this year,” Bell said. “Another thing we already mentioned is we are going to see an increased risk of flooding in unregulated sections of the Snake River Basin, especially south of the Snake River.”

North Idaho had low snowpack, faces severe drought

While snowpack in the Salmon, Weiser and Payette basins are peaking well below normal, they are not as bad as further north.

In North Idaho, the region has one of its lowest snowpacks on record. 

According to the water supply report, snowpack into the Clearwater Basin falls within the 10th to 14th percentile — a historically low range. The U.S.Drought Monitor also shows parts of North Idaho are experiencing abnormally dry to moderate and severe drought. 

Experts said the low snowpack levels have the potential to impact recreation and fisheries.