Environmental

PGE’s fish passage improvements lead to record-breaking coho salmon returns

PGE’s fish passage improvements lead to record-breaking coho salmon returns

Portland General Electric’s (PGE) Westside Hydropower Project on the Clackamas River in Oregon is generating record-breaking returns of coho salmon. The number of adult early run coho returning to the Upper Clackamas from the ocean hit 9,000 fish, the largest seen at North Fork Dam since its construction and the start of data collection in 1958.

The Westside project consists of six dams that impound water for powerhouses with a total capacity of 192 MW. They range in age from the 1.7-MW Timothy Lake powerhouse, which began operating in December 2018, to the 44-MW Faraday powerhouse built and commissioned in 1907.

Early run coho, which typically pass upstream from September to October, are followed by a population of late-run fish that return from November to January. PGE’s fish biologists at the project attribute the early run’s success to investments in fish passage infrastructure, which allow fish to bypass three dams safely and quickly. In particular, a floating surface collector in North Fork Reservoir, which became operational in 2016, captures more than 90% of ocean-going juvenile fish in the reservoir. This facility is the only surface collection system in the region to bypass fish through a multi-dam complex using a pipeline, without the aid of transport or trucking to a release site. 

“Survival rates through the bypass pipeline are around 99%, and collection rates are among the highest in the region, if not the world,” explained Garth Wyatt, PGE senior fish biologist at the plant. “Using our new facilities, the time that it takes juvenile coho to pass the dams was reduced from as many as twelve days down to only two and half hours.” This allows coho to arrive in the Lower Willamette River a bit earlier in the spring when water temperatures are cooler and predators are less active, increasing their odds of survival to the ocean. These survival gains, compounded by beneficial ocean conditions, have resulted in stronger adult returns and robust generations of young fish.

“We’re thrilled to see our investments and science-based strategies paying off,” said Wyatt. While coho returns were strong throughout the Columbia River Basin in 2021, results on the Clackamas River have been breaking records with increasing frequency. “We’ve observed record early run coho returns in four of the last eight years, all following infrastructure improvements,” he added.

Early run coho now represent the largest population of wild, ocean-going salmon in the Clackamas River Basin. Biologists expect this positive trend to continue, aided by collaborative habitat restoration projects, additional fish passage improvements and ongoing scientific research

PGE is a fully integrated energy company based in Portland, Ore., that serves about 900,000 customers with a service area population of 2 million Oregonians in 51 cities. PGE owns 16 generation plants across Oregon and other Northwestern states.