Lab Commended for Rapid Evaluation of Fish Passage
The Wanapum Dam fish ladder exit, normally under water, was exposed during the reservoir drawdown to repair the crack. This extension was constructed and added to the fish ladder to reduce the drop to the water surface from 26 to approximately 13 feet.
After 11 months of closure to accommodate repairs for a crack in a spillway pier, the Wanapum Dam shoreline on the Columbia River in central Washington reopened to the public on January 7, 2015. Fortunately for the river's fish population, upstream access was restored much earlier, with assurance of successful passage rates confirmed by researchers at PNNL. Their efforts earned a letter of recognition from the general manager of Public Utility District No. 2 of Grant County, Tony Webb. "These past few months serve as a reminder of how critical and valuable our partnership is during routine operations and especially during a crisis," Webb stated in his letter. "We operate with the recognition that we cannot fulfill our mission without partners − such as you − working with us along the way."
Acoustic Transmitters Track Fish Passage
In February 2014, the discovery of a fracture in a spillway pier at Wanapum Dam necessitated the lowering of the reservoirs behind the dam. The decreased water-surface elevation affected the operation of adult fish passage facilities at both Wanapum Dam and Rock Island Dam, about 38 miles upriver near Wenatchee, Wash. Emergency corrective actions involved modifying the exit of the adult fish ladder at Wanapum Dam, including the installation of pumps in the dam forebay to provide water flow within the fishway.
GCPUD requested that Battelle–Pacific Northwest Division evaluate passage success, timing, and behavior of adult spring Chinook salmon as they migrated through the modified fish ladders. Researchers in PNNL's Ecology and Hydrology technical groups quickly stepped up to the challenge and within two weeks had obtained the necessary approvals to start the project.
From April 26 to 29, they tagged 50 adult spring Chinook salmon with an internal micro-acoustic transmitter at the adult fish facility at Priest Rapids Dam, about 19 miles downstream from Wanapum Dam. The tagged fish were released immediately and monitored by a series of autonomous and cabled acoustic receivers as they migrated upstream to Wanapum Dam and beyond to Rock Island Dam. All 50 tagged fish successfully migrated upstream to Rock Island Dam; 47 of the 50 acoustically tagged fish made the trip in less than 14 days, which was the criterion GCPUD was being held to by the management agencies and tribes.
"The partnership that has occurred among local, state and federal agencies and tribes has been astounding and extremely helpful to Grant PUD during this difficult time," Webb further stated in his letter. "Please extend our sincere appreciation to all of your staff for their support during the response. Grant PUD values your partnership."
Overall, the fish ladder improvements implemented by GCPUD successfully facilitated the upstream migration of adult spring Chinook salmon in the spring of 2014. Information collected by PNNL staff demonstrated to GCPUD and management agencies that the upstream passage of fish was not affected by the lowering of the reservoirs behind the dam.
"Our challenges related to the Wanapum Dam spillway response would have surely been compounded had it not been for the willingness of PNNL to step up and help us in short order," Webb further stated in his letter, "…this experience demonstrates that when we work toward a common goal, we can accomplish positive things in short periods of time."
As a regional resource, the Lab continues to work with the hydropower community to help solve scientific and environmental challenges associated with turbine operations and fish passage. A recent PNNL press release describes the latest advances in PNNL’s fish tracking technology.
To read more about the Wanapum Dam spillway response and reopening of the shoreline, visit the Grant County PUD website.