Between 1941 and 1968, the Army Corps of Engineers constructed, and now operates, a system of 13 dams and reservoirs in the Willamette River drainage system in the state of Oregon. That system begins south of Cottage Grove, Ore., and extends north to the Columbia River. The Willamette basin is bounded by the Cascade Mountains on the east and by the Coast Range on the west.
Most of the Willamette Valley Flood Control Project dams are “high head” and more than 250 feet tall. Their primary purpose is to provide critical flood damage reduction for the entire Willamette Valley, including the cities of Eugene, Salem and Portland. The projects provide some hydroelectric generation (about 180 megawatts annually), along with recreational and fishing opportunities, water quality benefits, and municipal and irrigation water. The Willamette Project includes maintenance of 42 miles of revetments and operations of a hatchery mitigation program. Reducing the adverse effects of Willamette Project impacts is one component of the basin’s ESA draft recovery plan for salmon and steelhead.
Most of the dams do not include fish passage, and those that do are not very effective at passing fish. In March 1999, NOAA Fisheries listed upper Willamette River Chinook and steelhead under the Endangered Species Act (ESA). The Willamette Project has adversely affected those fish by blocking access to a large amount of their historic habitat upstream of the dams, and contributing to degradation of their remaining downstream habitat. Other factors in the decline of Willamette fish include habitat degradation by others, hatchery effects, and harvest.
The ESA requires NOAA Fisheries to assess whether federal actions will jeopardize the continued existence of listed species. The agency does this through a process of consultation with the action agencies; for the Willamette those are the Bonneville Power Administration, Corps of Engineers and Bureau of Reclamation. Consultation results in NOAA’s issuing a biological opinion, also called a BiOp or BO. NOAA Fisheries has been working with the federal action agencies for many years to complete an ESA biological opinion on how Willamette project operations impact listed salmon and steelhead.
Although the Willamette River Basin is part of the Columbia River Basin, NOAA considers Willamette hydropower projects separately in assessing how they impact ESA-listed salmon and steelhead.
