Considering Fish in the Management and Operation of Hydroelectric Dams in the Mainstem of the Columbia and Snake Rivers, USA

The operation and management of hydroelectricity dams impact fish by altering freshwater habitat above and below the dams. Dams in the Columbia and Snake rivers mainstem impact fish and their habitat, e.g., changing water temperature, flow, total dissolved gas, habitat availability, blocking fish passage, and shifting flow peaks. The Northwest Power Act tasks the Northwest Power and Conservation Council to find the best ways to operate the hydrosystem so as to improve the survival of affected fish while meeting the region’s growing electricity demands. To this end the Council develops a 5-year Power Plan, which integrates fish and wildlife requirements described as measures in the Council’s 5-year Columbia River Basin Fish and Wildlife Program (Program). Measures in the Program aim to protect, mitigate, and enhance fish affected by the hydrosystem, and thus include measures that require certain mainstem flow and passage. These flow and passage measures alter the energy, capacity, and flexibility of the hydropower system. We will discuss the various impacts of hydroelectricity dams on fish, Program measures recommended and implemented to alleviate these impacts, and how these Program measures are taken into account when developing the Power Plan for meeting the hydroelectricity needs of the region.