Oregon water supply outlook remains strong
All basins in Oregon are experiencing near normal to well above normal snowpack conditions, with a statewide average of 126 percent as of April 1 , according to the latest water supply outlook report released Thursday by the USDA Natural Resources Conservation Service in Oregon.
Warm temperatures and rain-on-snow during mid-March caused widespread snowmelt throughout the state. The most notable amounts of snowmelt occurred in eastern Oregon, where some sites lost more than twice the normal amount during the month. However, the previous three months of cold winter storms built sizeable snowpacks across the state, which remain near normal to above normal despite recent melt losses.
The last time the state had a well above normal snowpack on April 1 was in 2012, when the snowpack was 120 percent of normal. Last year, Oregon’s snowpack was 101 percent of normal on April 1 . Current conditions are favorable for abundant spring and summer surface water supply.
“This winter has seen consistent snow accumulation, while the beginning of the snowmelt season has resulted in variable snowpack in each basin,” said Scott Oviatt, NRCS snow survey supervisory hydrologist. “Snow at many lower elevation sites has melted, or is actively melting, while higher elevations sites have yet to fully enter their seasonal melt phase. The return of colder temperatures late in March helped preserve the snowpack following the mid-month warm and wet periods.”
Before recent snowmelt, most Oregon snow telemetry (SNOTEL) sites had surpassed their normal annual peak snow amounts and were recording a well above normal snowpack. The surplus of snow from the cooler winter months resulted in an above normal statewide snowpack as of April 1 , despite the accelerated snowmelt in mid-March.
Precipitation for the month was well above average and brought twice the normal amount at some locations. Eleven SNOTEL sites broke records for the highest or second highest March precipitation. The lowest amounts of monthly precipitation fell in southeastern Oregon at 136 percent of average in the Owyhee and Malheur basins, and in the Lake County region. The wettest region in March was in the Hood, Sandy, and Lower Deschutes, which recorded 186 percent of average precipitation.
“The snowpack that remains in the mountains is significant, so our summer streamflow forecasts continue to show promise for the spring and summer,” Oviatt said. “As of April 1 , the streamflow volume forecasts are calling for above average to well above average summer streamflows during the water supply season throughout the state.”
As of the end of March, many reservoirs across the state are near or above normal levels for this time of year. For the first time since 2012, the largest reservoir in the state, Lake Owyhee, is storing above average amounts of water (136 percent of average).
The latest information on Oregon’s streamflow forecasts can be found in the April Water Supply Outlook Report available on the NRCS Oregon website.
The NRCS Snow Survey is the federal program that measures snow and provides streamflow forecasts and snowpack data for communities, water managers and recreationalists across the West. In Oregon, snow measurements are collected from 81 SNOTEL sites, 42 manually measured snow courses, and 26 aerial markers. Water and snowpack information for all SNOTEL sites nationwide is available on the Snow Survey website in a variety of formats. The reports are updated every hour and are available at: www.or.nrcs.usda.gov/snow
NRCS publishes six monthly Oregon Water Supply Outlook Reports between Jan. 1 and June 1 every year. To regularly receive this information as an email announcement, visit the Oregon NRCS Snow Survey website and click the “email updates” icon to subscribe.
