PORTLAND — What a difference a month makes.
Oregon snowpack was averaging just 73% of normal at the beginning of February, setting the stage for low spring and summer stream flows, particularly west of the Cascade Range.
The story has been much different in March, after weeks of record-breaking snowfall and precipitation from Crater Lake to Baker City. Every basin in the state is now measuring above normal for snow, except for the Hood, Sandy and Lower Deschutes basins, which were at 93% as of March 11.
The USDA Natural Resources Conservation Service has released its latest monthly Oregon Water Supply Report, which calls for vastly improved conditions based on the sudden surge of winter weather.
“A remarkable and unexpected recovery in snowpack occurred during the shortest month of the year, dramatically improving the water supply outlook across Oregon,” the report states. “February storm cycles more than doubled the amount of snow on the ground in most locations, breaking many records along the way.”
According to the NRCS, seven of Oregon’s long-term snow monitoring sites broke records for highest snowpack on March 1, with data going back 35 years. Between Feb. 20-26, almost every snow measurement site from Crater Lake to Mount Jefferson set records with 2 to 3 feet of fresh powder.
As a result, most basins went from a snowpack deficit to a surplus, including:
• Willamette Basin, 51% of normal to 109%.
• Rogue and Umpqua basins, 60% to 115%.
• Klamath Basin, 69% to 119%.
• Upper Deschutes and Crooked basins, 66% to 112%.
Eastern Oregon is also piling up the snow, with the Umatilla, Walla Walla, Willow, John Day, Malheur and Goose Lake basins all topping 150% of normal. Precipitation at lower elevations also set records in places like Heppner, Baker City and Malheur County.
“All of the state just dramatically improved for snowpack,” said Julie Koeberle, a hydrologist with the NRCS Oregon Snow Survey team.
More snow is, of course, good news for farms and fish. Koeberle said forecasts are looking especially promising in northeast Oregon, with stream flows predicted to be 140% of normal from April through September in the Umatilla, Walla Walla and Willow basins.
A few areas, including the Deschutes River basin and Mount Hood, are still lagging behind at 80 to 95% of normal stream flows. But based on the current trajectory, Koeberle said most of the state is going to have normal to above normal stream flows heading into spring.
The one caveat, Koeberle said, is avoiding sustained periods of warm weather that can melt snow too quickly — as it did last May, diminishing what was an already sparse snowpack and leading to water shortages and drought statewide.
The U.S. Drought Monitor still shows more than 60% of Oregon in moderate to severe drought.
“You can’t really get rid of drought with just one good wet month. It takes a little more than that,” Koeberle said.
The federal Climate Prediction Center, meanwhile, continues to call for a better chance of higher temperatures over the next three months, and a roughly equal chance of dry or wet weather. If warmer weather does melt away snow quickly again, Koeberle said the impacts could be mitigated if Mother Nature comes through with enough spring rain.
“It’s really just kind of a wait and see,” she said.
Reservoir levels are a bit more hit and miss across the state, storing anywhere from 65 to 97% of capacity, though most can expect significant inflows in the coming months as snow begins to melt.