The Thomas W. Sullivan Plant has incorporated new technology to further bolster the migration success of steelhead and salmon on the Willamette and its namesake falls.
Fish bypass at Willamette Falls
As part of this effort, PGE has installed a flow control structure at Willamette Falls focused on helping smolt (juvenile salmon) complete their journey to the Pacific Ocean.
The 200-foot-wide gated flow control structure, located at the tip of the falls, features a concrete and rubber “ramp” that helps fish avoid the rocks below by guiding them to the deep water at the base of the falls.
To make this possible, three inflatable rubber dams were installed across the tip of the falls, helping PGE control the flow of water and steer fish to the safest passage.
The project was completed in fall 2007 and included development of mooring structures above the falls as anchors for work barges and construction of a coffer dam for work on the dry riverbed.
The bypass enhancements at the two primary downstream migration routes (the powerhouse and the falls) have improved the success of downstream migrants passing the Willamette Falls on their way to the Pacific Ocean. During 2008 and 2009, PGE fisheries biologists tagged or micro-chipped over 15,000 fish in two studies at our T.W. Sullivan Plant. Results show fish survival rates in a excess of 98 percent at the powerhouse and 97 percent at the falls.
Sullivan earns green designation
In March 2008, the Low Impact Hydropower Institute Board certified Sullivan as low impact based on these extensive fish protection and passage improvements, including installation of the second fish bypass system and construction of the flow control structure at the apex of the falls.
This designation means the Sullivan hydro project is now an official producer of green power, joining PGE’s Pelton Round Butte project as two of only a few dozen hydro plants in the U.S. to have earned this distinction, including just one other Oregon facility. For more, see the news release.
Other Sullivan Plant upgrades
The falls bypass project follows the construction of a second downstream migrant fish bypass system at the T.W. Sullivan powerhouse completed in 2006. The north fish bypass is a high volume bypass designed for flows up to 500 cfs.
The next few years will see continued testing of the flow control structure and north fish bypass, maintenance of the state-owned fish ladder and completion of research on the adult Pacific lamprey eels. PGE will also replace 10 of the plant’s 13 turbines.