The Columbia Basin Project in Central Washington, United States, is the irrigation network that the Grand Coulee Dam makes possible. It is the largest water reclamation project in the United States, supplying irrigation water to over 670,000 acres (2,700 km2) of the 1,100,000 acres (4,500 km2) large project area, all of which was originally intended to be supplied and is still classified irrigable and open for the possible enlargement of the system. Water pumped from the Columbia River is carried over 331 miles (533 km) of main canals, stored in a number of reservoirs, then fed into 1,339 miles (2,155 km) of lateral irrigation canals, and out into 3,500 miles (5,600 km) of drains and wasteways. The Grand Coulee Dam, powerplant, and various other parts of the CBP are operated by the Bureau of Reclamation. There are three irrigation districts in the project area, which operate additional local facilities.

Grand Coulee Dam is a concrete gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. Constructed between 1933 and 1942, Grand Coulee originally had two powerhouses. The third powerhouse ("Nat"), completed in 1974 to increase energy production, makes Grand Coulee the largest power station in the United States by nameplate capacity at 6,809 MW.