Mid-January storms have brought the previously lagging Idaho snowpack much closer to long-term averages.
Snowpack in many of the state’s basins ended 2019 at 50% to 79% of normal, USDA Natural Resources Conservation Service said in the Jan. 1 Idaho Water Supply Outlook Report. The accumulation season officially began Oct. 1.
By Jan. 15, river basins along the state’s southern and northern borders had above-normal snowpack, NRCS reported. Elsewhere, percentages of the long-term average ranged from 95 to 117 along the eastern border from north to south, and 69 to 99 in central, western and northern regions.
From Jan. 1 to 15, snowpack rose from 68% to 91% of normal in the Weiser River Basin. Snowpack in Boise and Payette basins gained more than 30 percentage points, to about 90%.
“January and February normally have a way of making it up,” said Sid Freeman, who farms northwest of Caldwell, Idaho. “If we are short going in, we are not too concerned.”
Danny Tappa, supervisory hydrologist with NRCS Idaho Snow Survey, said the amount of water in reservoirs carried over from 2019 is well above normal, which gives irrigators a head start on water supply for the 2020 growing season.
For example, there would be enough water to fulfill irrigation demand in the large Snake River Basin if streamflow for the year amounts to around 60% of normal, thanks to the strong carryover storage, he said.