Snowpack levels across Washington remain far below normal as the state approaches the critical statewide median peak snowpack date, raising concerns about water supply heading into the warmer, drier months.
According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service, statewide snow water equivalent — a key measure of how much water is stored in the mountain snowpack — stood at just 54% of normal entering the month of March. The historical median peak snowpack date of April 5 is now just a couple of weeks away.
“It will take a significant change in weather patterns to make up ground,” the March 1 Washington water supply outlook report by the USDA stated.
As of March 1, data collected through the SNOTEL network, which is a system of remote monitoring stations tracking snowpack conditions, highlighted just how severe the snowpack shortfall has become entering the final days leading up to the median peak. Five stations recorded their lowest snow water equivalent levels on record, while nine others reported their second lowest, the report stated.
The Calamity SNOTEL station, just outside of Clark County in Skamania County forestland, has a 1991-2020 snow water equivalent median of 2.4 inches. By the end of day on Wednesday, March 18, it measured at zero inches. The Swift Creek SNOTEL station, which is located near the southern flank of Mount St. Helens, is measuring at 30.2 inches of snow water equivalent, in comparison to the 1991-2020 median of 62 inches.
While conditions vary by region, not a single basin in the state entering March was at snow water equivalent normal levels. The North Puget Sound basin was the closest to 100%, which would match the 1991-2020 median level, at 72% of normal snowpack.
In Southwest Washington, the Lower Columbia basin sat at just 49% snowpack entering March.
Six basins in total reported less than 50% of their median snowpack for this time of year. Among the hardest hit are the Upper Yakima Basin at 35%, the Central Puget Sound basin at 39% and the South Puget Sound basin at 36%.
Despite the snowpack deficits, precipitation totals for the current water year — which runs from Oct. 1 through Sept. 30 — have been near or above normal. However, the majority of that precipitation has been falling as rain, not snow, which the report labeled as a “snow drought.”
“If the current snowpack deficit persists through spring, most basins in Washington can expect to see below normal to slightly below normal runoff,” the report stated.
The snow drought distinction is significant as mountain snowpack serves as a natural reservoir, gradually releasing water into rivers and streams as warmer weather hits certain elevations. Without sufficient snow accumulation, water supply will not be able to keep up with normal demand, which will likely lead to water shortages and the need to conserve and tightly manage water usage across the state.
According to the U.S. Drought Monitor, the vast majority of Clark County and Skamania County land in the first degree of drought intensity entering this month, labeled “abnormally dry.”
“With only a couple of months in the snow accumulation season ahead, the March 1 forecasts are beginning to show more certainty in the relationship between current conditions and expected streamflow in late spring to early summer,” the report states. “Snowmelt in spring and early summer provide much of the water supply statewide for many different users and purposes. Forecasts of expected runoff assist water users and managers plan for conditions they may expect during peak summer usage.”
