Powering Strong Communities

Grand Coulee Dam Overhaul Project Ensures Another 30 Years Of Hydropower In The Northwest

The U.S. Bureau of Reclamation and the Bonneville Power Administration (BPA) recently announced the completion of the major overhaul of three hydroelectric power generating units inside the Nathaniel “Nat” Washington Power Plant at Grand Coulee Dam.

The project will ensure another 30 years of hydropower delivery in the region.

Located on the Columbia River about 90 miles west of Spokane, Wash., the Grand Coulee Dam is the largest power generating complex in the United States.

The dam can generate more than 6,800 megawatts (MW) and annually supplies more than 20 billion kilowatt hours of electricity to the region.

The project involved complete disassembly of each 805-MW hydroelectric unit, refurbishing each to ensure all of the mechanical and electrical surfaces were restored and returned to like-new condition.

Approximately 6.5 million pounds of steel were removed from each unit once every component down to the turbine runner was fully taken apart. While the units were disassembled, each component was sand blasted, welded, ground, polished, and then repainted before reassembly. Restoring the mechanical and electrical components results in less friction. As a result, the generating units operate with less wear and tear, making them more reliable and efficient.

Grand Coulee Dam provides about one-quarter of the total generation of hydroelectric power for the Federal Columbia River Power System and is one of 31 federal dams that generate more than half of the hydropower in the Northwest.

The Nathaniel “Nat” Washington Power Plant was built between 1967 and 1975 and is the largest of the four power houses. The plant contains six generating units capable of producing more than 4,200 MW, and it contributes to about two-thirds of the total power generated by the dam.

Completed in 1941, Grand Coulee Dam serves as a multipurpose facility, providing water for irrigation, hydroelectric power production, flood control, fish and wildlife conservation, and recreation. The Grand Coulee Power facility is comprised of 33 generators in three power plants, the John W. Keys III Pump-Generating Plant, and three switchyards.

BPA delivers power generated by the federal dams, one nonfederal nuclear plant and several small nonfederal power plants, to more than 140 Northwest electric utilities, serving millions of consumers and businesses in Washington, Oregon, Idaho, western Montana and parts of California, Nevada, Utah, and Wyoming.