Released On: December 10, 2008
The Sven Olbertson site is located just downriver from Lewiston Dam, part of Reclamation's Central Valley Project and adjacent to a Forest Service site where 9,000 tons of spawning gravel were added to the river during 2006 and 2007. It is one of eight locations treated in 2008 within the Lewiston-Dark Gulch Rehabilitation Project, designed to enhance salmon and steelhead's fresh water life cycle phase on this portion of the upper Trinity River, including the Federally threatened coho salmon.
Completion of Reclamation's Trinity and Lewiston Dams in 1964 blocked salmon and steelhead from reaching more than 100 miles of formerly accessible fish habitat upstream and for nearly 40 years resulted in the diversion of more than 75 percent of the inflows into the reservoir for irrigation and power generation purposes. Peak flows needed to maintain vital spawning and rearing habitat for oceangoing fish species that breed in fresh water were greatly reduced, which allowed stream-side vegetation to encroach and confine the river channel for about 40 miles below the dams.
More than 9 acres of choked stream-side and former flood plain habitat was treated at the Sven Olbertson site. A long low-flow side channel was built incorporating large trees and boulders to create complex rearing habitat. Backwater alcoves connected to the new side channel were excavated to promote fish and wildlife use. Nearly 13,000 cubic yards of former flood plain material was excavated, deposited elsewhere, and then reshaped during construction to form the complex new habitat.
When completed, the new rehabilitation sites and higher flow releases approved in the December 2000 Trinity River Mainstem Fishery Restoration Record of Decision should largely diminish these impacts and help reestablish fish populations at or near pre-dam levels.
Reclamation and the California Department of Fish and Game Fisheries Restoration Grant Program funded the effort. The U.S. Forest Service and Reclamation were co-lead agencies throughout the National Environmental Policy Act process, and the Trinity County Resource Conservation District was the lead agency for the California Environment Quality Act process.
For more information on the Trinity River Restoration Program, please call 530-623-1800 or visit http://www.trrp.net/.
The U.S. Forest Service sustains the health, diversity and productivity of 193 million acres of public land on 155 national forests and 20 grasslands to meet the needs of present and future generations. Nearly half of the fresh water generated each year in California originates from U.S. Forest Service land. Visit our website at http://www.fs.fed.us/.
DOI | Recreation.gov | USA.gov
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