Pelton-Round Butte Dam
(Oregon State Archives)
The Deschutes River begins high in the Cascade Mountains and tumbles down more than 4500 feet as it flows north to join the Columbia River. The watershed is renowned for its rocky desert canyons and river rafting, and is a popular destination for fly-fishermen seeking trout, salmon, and steelhead.
The river's steep topography also makes it an important river for hydropower. Between 1957 and 1964, Portland General Electric (PGE) constructed the Pelton-Round Butte Hydropower Complex, a sequence of three dams that produces enough electricity to power a city 150,000 people. The dams were equipped with fish passages to allow fish to continue to migrate up and down the river. However, the fish passages designed for the Round Butte Dam, the largest of the three dams, failed. In 1968, PGE abandoned its efforts to maintain anadromous fish populations in Lake Billy Chinook, the reservoir upstream of the Round Butte Dam. That decision prevented the migration of salmon and steelhead into 226 miles of river, about two-thirds of the Deschutes River system.
An Upstream Battle
This dramatic loss of fish habitat was not easily accepted. When the Pelton-Round Butte dams faced federal relicensing in the 1990s, twenty-two agencies and groups came together to discuss mitigating the environmental impacts of the dams. In 2004, the panel reached an agreement: PGE and the Confederated Tribes of Warm Springs would jointly operate the dam complex and commit to a $130 million plan to restore anadromous fish to the watershed.
This ambitious plan involved the construction of a 273-foot underwater tower that would change water currents in Lake Billy Chinook and direct fish into a sorting facility. Larger fish would be returned to the lake, and smaller, migratory fish would be tagged and trucked around the dams to be released into the lower river. By retrofitting existing fish ladders, adult fish could return upstream. However, this $100 million apparatus has not been as easy to complete as anticipated. Scheduled to have been finished by winter, 2009, the fish ladder broke during installation in April, 2009, sending several pieces 270 feet to the lake bottom. The pieces have since been retrieved, however, and the facility was completed in spring 2010.
The Salmon Return
In December, 2009, the fish passage has succeeded in its job of rerouting juvenile salmon, or smolts, around the dam -- the first transfer of fish occurred only hours after water began flowing through the structure. The fish, drawn into a sorting facility by water currents, fell into a holding pen where they were scooped out, marked, and loaded onto trucks. They were then driven around the dams and released into the Lower Deschutes.
Several problems surfaced during a month-long testing period at the sorting facility soon after the facility's completion. One problem that was addressed was the fluctuating water levels within the holding pens. During the first few days of operation, the pen released its water overnight, killing the few fish in the pen. Later, the water level rose so high that one fish jumped out, stranding itself on a platform. Crews adjusted the water flow, and the 10 to 25 fish that enter the facility each day have done so safely. The real test, according to engineers, would come in the spring, when thousands of young fish would enter the facility each day.
As of May, 2010, thousands of juvenile kokanee and chinnook salmon and steelhead have successfully passed through the dam on their way to the ocean. The kokanee salmon have even picked up a new name for the occasion, and are now known as sockeye salmon, the ocean-going version of their former land-locked selves. Along with sockeye salmon, chinook and steelhead have also been transported around the dam. Some of the young fish, equipped with radio transmitters, have since been recorded passing through the Bonneville Dam on the lower Columbia, 160 miles away. The immediate success of the Pelton-Round Butte fish passage tower is an encouraging step in the process of restoring salmon and steelhead populations in the Deschutes Basin.
Still, success cannot truly be measured until the smolts passing through the facility today return in two years as adult salmon. Ultimately, the crew at the dam hope to see a self-sustaining population of salmon and steelhead that do not require supplemental fish from hatcheries. In addition, biologists are working to produce a more natural temperature range in the Lower Deschutes by taking water from the top or the bottom of the river at different times of the year. Although this process has only been modeled on a computer, engineers will monitor temperature changes, and are optimistic that the program will be a success. Engineers will also ensure that the fish collection operation does not interfere with the dams power production.
Portland General Electric hopes to use the techniques learned from this facility to build a similar facility on the Clackamas River. After a two-year construction process and numerous setbacks, this unique facility at the Pelton-Round Butte Dam is helping both fish and humans reach their goals.
Sources
Deschutes River Conservancy. Fish sorting facility update. April 17, 2010.
Portland General Electric. Updates and news about the dams and fish facility.
Deschutes Passage. Background on the dams, their partnerships, and fish facility construction.
