Rangeland may dry out prematurely, but reservoirs full
By JOHN O'CONNELL
March snowpack fluctuated widely throughout Idaho, breaking moisture records at 25 meteorological monitoring sites from the Big Lost River Basin to the northern Panhandle but leaving the mountains south of the Snake River unseasonably dry.
Jeff Anderson, a Natural Resources Conservation Service hydrologist, said despite Southern Idaho snowpack levels that dipped to 40 to 60 percent of normal by the end of March, there should be plenty of water to last irrigators through the current growing season thanks to strong storage reservoir carryover.
"There was a huge increase in some basins and a huge decrease in other basins. That was a huge story in March," Anderson said.
Anderson said snow melt has been about two weeks ahead of schedule in Southern Idaho, where about 22 percent of snowpack was lost within the Bear, Blackfoot, Bruneau, Owyhee and Portneuf basins.
Absent a wet spring in Southern Idaho, Anderson said rangeland could be prematurely dry, especially from Burley west to the Oregon border.
"I've talked to a couple of people who are concerned about that," Anderson said.
The NRCS tracks records dating back 30 years. In the Schweitzer Basin, in the Selkirk Mountains of Northern Idaho, 18 inches of moisture fell during March, shattering the old record by 11 inches. Two meteorological monitoring sites in the headwaters of the Big Lost River Basin received three times the normal March precipitation. Anderson said the Big Lost drainage had a "really poor winter even up to March 1" and was brought to more usual levels.
Heavy March snowfall brought Idaho's Panhandle snowpack to 120 percent of normal and Central Idaho levels to 80-110 percent of normal.
The complete April 2012 Water Supply Outlook is available at www.id.nrcs.usda.gov/snow . Click on the 'Water Supply' link.