Juvenile salmon and steelhead passage is now underway at Wanapum and Priest Rapids dams. Juvenile passage at Wanapum Dam will be accommodated through the dam’s fish
Three spillways at Priest Rapids Dam were modified to create the Priest Rapids Dam Fish Bypass Unit.
bypass unit, spillways and advanced turbines, which all remain functional under the current reservoir elevation. At Priest Rapids Dam, the newly-installed Priest Rapids Fish Bypass is operational in time for the downstream migration.
Construction on the new Priest Rapids Fish Bypass began in 2011, and is built upon the success of the Wanapum Dam fish bypass approximately 19 miles upstream. The bypass design converts three existing spillways into fish slides at Priest Rapids Dam to provide downstream passage for migrating fish in addition to the spillways and turbines. The three chutes are each more than 200 feet long and over 40 feet wide. Collectively, the fish bypass chutes are capable of passing 27,000 cubic feet per second of water and juvenile fish survival is anticipated to be 99 percent.
The bypass unit is designed to safely pass fish over the dam while saving water for generation.
The bypass provides for a better use of water resources by reducing total water spilled for juvenile salmon from 110,000 cubic feet per second (cfs) to 27,000 cfs. This efficiency allows for an increase in power generation while also improving fish passage. At a cost of $28 million, the project is anticipated to pay for itself in five to seven years with the increased potential for electric generation.
Beginning this week, Grant PUD will begin transporting and releasing approximately 3,400 tagged juvenile steelhead and yearling Chinook salmon approximately 38 miles above Wanapum Dam via helicopter as studies on juvenile fish passage commence. These studies are a component of Grant PUD’s license requirements, specifically the NOAA Fisheries Biological Opinion and the Priest Rapids Salmon and Steelhead Settlement Agreement from 2008. The studies will evaluate the survival and behavior of juveniles moving through the new Priest Rapids Dam Fish Bypass as well as fish passage throughout the Priest Rapids Project.
Results from the studies will inform Grant PUD and other agencies of potential impacts on juvenile salmon and steelhead during the low-river conditions. Results will also provide route-specific behavior and survival information through the Wanapum and Priest Rapids dam fish bypasses, spillways and turbines.
Adult fish passage continues through modified fish ladders at Wanapum Dam. As of April 23, 31 adult spring chinook adult salmon and 270 steelhead have been counted exiting the modified fish ladders at Wanapum Dam to continue their upstream migration. Grant PUD continues to trap and haul fish at Priest Rapids Dam while the ladder modifications are being evaluated under operating conditions. As of April 27, 74 spring chinook and 27 steelhead have been captured at Priest Rapids Dam and transported past Wanapum Dam.
The Wanapum reservoir shoreline will remain closed during the current low-reservoir elevations to protect culturally-sensitive areas and for public safety. Grant PUD expects that the shoreline closure will remain in effect at least through the July 4th weekend.
All of the 11 irrigators with surface-water withdrawals on the Wanapum reservoir have successfully acquired permits to modify their irrigation systems. Under the current reservoir elevation, Wanapum Dam continues to generate electricity at about 50 to 60 percent of its capacity and is passing spring runoff flows in coordination with other dam operators on the river.
For additional information, visit: http://www.grantpud.org/your-pud/media-room/wanapum-dam-spillway-response.
Established by local residents over 75 years ago, Grant PUD generates and delivers energy to millions of customers throughout the Pacific Northwest. What began as a grassroots movement of public power has evolved into one of the premiere providers of renewable energy at some of the most affordable rates in the nation. For more information visit www.grantpud.org or follow us on Facebook and Twitter.
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