SEATTLE (AP) — Warm temperatures and a lack of snowfall in February have taken a toll on winter snowpack in the Cascade Mountains and other areas in the West, the U.S. Natural Resources Conservation Service said Wednesday.
One-third of monitoring sites in the Cascades and Sierra Nevada reported the lowest snowpack ever measured as of March 1, and some sites don't even have snow, unusual for this time of year.
The March forecast also shows that snowpack in Nevada, Utah and Idaho fell farther below normal.
"Snowpack along the Continental Divide is about normal, but it drops off as you go South and West," said Cara McCarthy, a hydrologist with the service, a branch of the U.S. Department of Agriculture. "If the weather doesn't change, we're looking at low-stream flow in a lot of areas."
Snow that falls in the mountains during the winter typically melts slowly during spring and summer, providing water for much of the region. A lack of snowpack can lead to drought. Low-flowing rivers in the summer also may affect fish, wildlife, livestock, municipal water supplies and hydropower production.
"The snowpack in the Western U.S. is counted on to be an additional reservoir that holds a whole bunch of water, so that water is released slowly as the snow melts. Westerners count on that snow for spring and summer, for irrigation and other water uses," McCarthy said.
Snow surveyors in many places across the region reported seeing little or no snow at sites they visited. In Oregon, for example, about 45 percent of the snow-monitoring sites are snow-free.
Statewide in Washington, the snowpack was 29 percent of a 30-year median as of March 1. The amounts varied widely by region, from a record low 2 percent of normal in the Olympic Mountains to 85 percent of normal in the Methow basin in north-central Washington.
Still, while snowpack has been below normal in Oregon and Washington, there has been plenty of rain. Those states have seen near-normal precipitation since fall. Some reservoirs have benefited from the rainy winter.
In Montana, the lack of snowfall and rain, as well as warmer than usual temperatures, led to a decrease in snowpack. Statewide, the snowpack is at 91 percent of normal as of March 1.
In south Idaho, snowpack range from 22 percent of median in the Owyhee basin to 115 percent in several Snake River headwater drainages in Wyoming.
"If February's dry weather continues for one more month, we'll be writing a different story in the April 1 water supply report," according to the Idaho water supply outlook.