Low winter snowpack combined with a drier-than-usual spring and rapid snowmelt will likely translate into critically low water supplies across parts of Oregon heading into summer, according to the USDA Natural Resources Conservation Service.
The NRCS released its June basin report for Oregon, and the outlook is bleak, especially in southern and eastern Oregon. Gov. Kate Brown has already declared a drought emergency in Klamath, Grant, Harney and Lake counties, while the U.S. Drought Monitor shows nearly the entire state in some level of drought, from “abnormally dry” to “severe drought.”
Unusually warm weather in May led to rapid melting of already limited snowpack, said Scott Oviatt, snow survey supervisor and hydrologist for the NRCS. Of 81 real-time snow monitoring stations, only five still have snow as of June 1.
Snowpack is critical for water management, since it acts as a natural reservoir gradually replenishing streams into spring and summer. However, most of Oregon’s snowpack peaked around 70 percent of normal and melted away quickly over the last month.
Snow has almost completely disappeared statewide, except for basins in the far northeast corner of Oregon, which are still clinging to 27 percent of normal levels. Many sites melted out one to two weeks ahead of schedule, and several higher elevation sites had snow melting up to 2 1/2 times faster than usual.
Streams in the drought-stricken Klamath, Harney, Goose Lake and John Day basins are projected to run just 26-82 percent of normal levels through September. Forecasts improve closer to the Columbia River and west of the Cascades, which received closer to normal snowpack.
The Umatilla, Walla Walla and Grande Ronde rivers should experience near-average stream flows in northeast Oregon. The Willamette Basin, home to more than 1 million acres of farmland, should see streams flows ranging from 48 to 87 percent of normal, along with the Hood, Sandy and Upper Deschutes basins.
In southwest Oregon, forecasters anticipate the Rogue and Umpqua rivers will be slightly lower, at 47 to 81 percent of average.
Reservoirs remain a bright spot in this year’s water outlook. Most of the state’s major reservoirs are holding 70 to 110 percent volume, with the Umatilla, Walla Walla and Willow basin reservoirs faring best at 95 to 111 percent full.
The NRCS is advising irrigators to plan accordingly for water shortages, “especially in southern and southeastern Oregon where the snowpack was the lowest this season.”