Willamette River Biological Opinion

The Willamette Valley Flood Control Project consists of 13 dams operated by the Corps of Engineers. Most of these dams are "high head" dams that are over 250 feet tall. The primary purpose of the dams is to provide critical flood damage reduction for the entire Willamette Valley, including the cities of Eugene, Salem and Portland. The projects also provide some hydroelectric generation (about 180 mw annually), along with recreational and fishing opportunities, water quality benefits, and municipal and irrigation water. The Willamette Project also includes maintenance of 42 miles of bank protection projects and operation of a hatchery mitigation program. Reducing the adverse effects of the Willamette Project is one component of the basin’s ESA recovery plan for salmon and steelhead.

The Willamette Project has adversely affected Upper Willamette River Chinook and steelhead by blocking access to a large amount of their historic habitat upstream of the dams and contributing to degradation of their remaining downstream habitat. The associated mitigation hatcheries that accompanied the dam building had an effect on the genetic diversity of Chinook populations in the Willamette basin. Other factors in the decline of Willamette salmon and steelhead include habitat degradation by others, hatchery effects, and harvest.

In its Reasonable and Prudent Alternative, NOAA Fisheries identified measures and timelines for completion that the Corps, Bonneville Power Administration, and Bureau of Reclamation (collectively, the Action Agencies) must implement to reduce the Project’s effects. These measures include providing fish passage at three dams, temperature improvements downstream of another dam, improvements in downstream flows, screening of irrigation diversions, improving hatchery practices and facilities and habitat improvement projects. In addition, the Willamette Action Agencies will carry out a series of research, monitoring, and evaluation measures to develop appropriate actions and evaluate their effectiveness.

A new entity called the Willamette Action Team for Ecosystem Restoration (WATER) fosters an ecosystem-wide perspective and cooperation among all concerned parties, including states and Tribes. Five teams address implementation and adaptive management. For more information on how the Willamette Action Agencies are implementing this Biological Opinion, visit:

The Willamette Biological Opinion is not a long-term salmon recovery plan. While efforts to make the dams more fish-friendly, to improve river water temperatures, and to improve hatchery practices will measurably aid long-term recovery efforts, please visit the Upper Willamette Recovery Planning subdomain to learn more about the Willamette Recovery Plan.