Mountain snowpacks across the Pacific Northwest got a welcome boost from February storms, though most levels remain well below average, and California’s water outlook improved slightly despite the drought that grips the state.
In Oregon, the statewide average snowpack increased from about 37 percent of average to 57 percent of average during February, said Melissa Webb, a hydrologist with USDA’s Natural Resources Conservation Service.
While Oregon got a lot of snow and rain this month, precipitation would need to stay at an elevated level through spring to make up for the earlier dry months, she said.
Temperatures in southern Oregon didn’t drop as low as other areas of the state, which means the region got more rain than snow, Webb said.
“They saw a lot of moisture but their snowpack is still at about a third of normal,” she said.
For irrigators with access to reservoirs, rainfall is still good news, but growers in some areas rely mostly on snowpack for water storage, Webb said.
Washington got an even bigger reprieve courtesy of the February storms. The statewide snowpack increased from 55 percent of average to 78 percent of average, said Scott Pattee, a water supply specialist with NRCS.
“We’ve seen some major increases,” he said. “It definitely has improved.”
Even so, snowfall would have to stay 50 percent higher than normal to bring Washington up to average by April 1, the typical peak for mountain snowpacks, he said.
In areas with snowpacks hovering above 80-90 percent of average, like the Upper and Lower Yakima basins, the water supply outlook is decent, Pattee said.
In Idaho, the state Department of Water Resources intends to notify Eastern Snake Plain Aquifer groundwater users of a significant improvement in the state’s water outlook.
On Jan. 28, the outlook was so dry that the department mailed a warning letter to the 1,700 stakeholders outlining potential groundwater curtailment scenarios. By Feb. 15, the change in weather patterns had improved snowpack in the Upper Snake from 97 percent of median to 115 percent of median.
Snowpack also increased from 46 to 76 percent of median in the Big Wood Basin, 50 to 78 percent of median in the Boise Basin and 53 to 73 percent of median in the Payette Basin.
“The ones that we’re still looking at a shortage but are significantly better than a month ago are the Weiser, Owyhee and Bruneau basins,” said Rick Raymondi, the department’s bureau chief of technical services. “Those improved but are still enough below the percent of median that there’s still a concern for them.”
Raymondi emphasized water may still be a bit short in the Magic Reservoir, despite the improved snowpack in the Big Wood Basin, because much of the reservoir was drained last season for dam repairs.
In California, an early February storm “minimally” helped snowpack levels and the state continues to face drought, said Frank Gehrke, chief of the state’s Cooperative Snow Surveys Program.
“It made a dent in the storage but overall there has been no big change,” Gehrke said.
At this point, the statewide snowpack level is at 25 percent of average, with the northern portion of the state seeing the greatest shortage.
A ridge of high pressure air over California, and to a lesser extent Oregon, has been deflecting storms toward Canada and the Eastern U.S., he said.
The water shortage has already resulted in mandatory conservation measures and landscaping irrigation restrictions in some areas, Gehrke said.
Unless the high pressure ridge dissipates soon, the irrigation outlook is dire, he said.
“The reservoir storage is about three-fourths of average and dropping,” Gehrke said. “I think it’s going to be very significant.”