On Tuesday, July 23, about 30 HydroVision attendants had to the benefit of touring the 136-MW Lewis River hydropower plant which is located at the Merwin Dam in Ariel, Washington. In 1931 the dam was constructed and has four penstocks, which today feed three turbines. The turbines have been put in 1931, 1949 and 1958. The fourth penstock, which was the center of much of the tour, is for fish passage.
FERC in 2018 renewed PacifiCorp’s license to operate and ordered the utility to offer downstream passage at Merwin Dam for the Chinook, Coho, and Steelhead. Today, by way of a $50 million project, the fish travel via a complicated but elegant system of “chutes and ladders” lastly landing in a sorting pond, the place biologists depend, tag and sort, by hand, the different species into holding tanks. Trucks then ship the fish to varied areas downstream where they’re released. Specific species of the fish go to hatcheries to assist the population increase.
The controls for the sorting facility were designed by Bruce Benson of Black and Veatch (sponsor of the tour). Benson attended the visit to assist reply questions from attendees. He mentioned that from April to December within the first year of operation, 31,994 fish were hand-sorted by the facility.
“I designed the control system part of it, turning the pumps on, a typical pump-turbine, valves, operation, things like that,” Benson defined on the bus ride to Ariel.
The facility helps PacifiCorp remain compliant with the FERC order and show that there is a minimum of an 80 % survivability rate for the fish that move through the dam.
A video of the tour, produced by Clarion Energy, should be on the website later this summer.