Portland, Ore. --
As recent weeks have brought more precipitation to the Willamette Valley, the U.S. Army Corps of Engineers, Portland District (Corps) anticipates better water refill throughout the summer than previously forecast.
To inform the public on water conditions, forecasts and management throughout the Valley, the Corps invites the public to attend a virtual information session Thursday, May 21 from 12 to 1 p.m.
Join us online: https://usace.webex.com/meet/WillametteWaterManagement
Call: 1-877-402-9753 (US) (Call-in toll-free number)
Access Code: 932 700 4 #
Security Code: 928 37 #
A dry winter and early spring produced less than optimal water conditions throughout the Willamette Valley Project. Across most of the Willamette Basin, May precipitation has been good. The Corps anticipates most reservoirs to fill at the beginning of the conservation season, facilitating recreation through the summer. A few reservoirs may not fill completely, however.
The Corps hosted three virtual information sessions on water conditions, forecasts and management in early May. These recorded meetings can be viewed here: www.youtube.com/PortlandCorps/videos.
The Willamette Valley Project, comprised of 13 dams and reservoirs, is primarily a rain-driven system. Basin-wide, reservoirs are currently 80 percent full, sitting 20 percent below the rule curve, or the congressionally-authorized maximum reservoir water elevation for this time of year.
The National Oceanic and Atmospheric Administration (NOAA) forecast below-normal water supply and higher than average temperatures throughout Oregon over the next month. This forecast, along with the lack of precipitation received so far this year, is setting the stage for “abnormally dry” to “moderately drought” conditions to continue through summer.
Based on current conditions and forecasts, the Corps is working in collaboration with federal, state and local agencies. This collaboration helps to inform and plan water management operations that optimize the water resources available to balance the needs of up and downstream users in “drought year” conditions.
The Corps manages water across the Willamette Valley Project during the summer months to conserve reservoir water levels so that stored water can support water quality, water supplies and fish and wildlife habitat, while also benefitting reservoir-based recreation.
To meet legal requirements under the Endangered Species Act, the Corps must release specific amounts of water from each dam to maintain adequate downstream river flows for listed species.
These releases downstream also help maintain water quality and provide for contracted irrigation water. With these releases and surface evaporation during the drier summer months, many reservoirs are “drawn down” throughout the summer.
Willamette basin-wide snowpack was slightly above average earlier this spring. However, warmer temperatures have caused earlier snowmelt, dropping snowpack to less than 50 percent of average for this time of the year. Inflows benefitted early from this, but, as a consequence, there will be less benefit from snowmelt later in the summer.
To learn more about the Willamette Valley Project, visit https://www.nwp.usace.army.mil/Locations/Willamette-Valley/.