2. Grand Coulee Dam and The Columbia Basin Project: An Overview

2.1 Grand Coulee Dam

2.2 Columbia Basin Project

2.1 Grand Coulee Dam

The Grand Coulee Dam is over five thousand feet long, stands 550 feet tall, and is one of the largest concrete structures in the world. It is located on the mainstem of the Columbia River about 90 miles west of Spokane, Washington (see Figure 2) and is owned and operated by the U.S. Bureau of Reclamation (hereafter referred to as "Reclamation"). The dam began operating in 1941, and the structure was modified between 1966 and 1974 when a third powerhouse was added to increase the generating capacity of the hydroelectric works. A major bank stabilisation project was implemented between 1982 and 1988. Franklin D. Roosevelt Lake (or "Lake Roosevelt") extends about 150 miles northeast to the Canadian border, and up the Spokane River to within 37 miles of Spokane. The total storage capacity of Lake Roosevelt is approximately 9.7 million acre-feet, about 5.2 million acre-feet of which constitutes active storage capacity.

Figure 2. Grand Coulee Dam and Columbia Basin Project

Grand Coulee Dam's hydroelectric generating facilities include four powerhouses (including the pumping plant), with a total of 24 main generators, three station service generators and six pump/generators. These provide a combined generating capacity of 6,480 megawatts. These makes Grand Coulee Dam the largest single producer of hydroelectric power in the United States and the third largest such facility in the world.

The Grand Coulee Dam and Lake Roosevelt are key components of the Federal Columbia River Power System (FCRPS), which co-ordinates power production in the Pacific Northwest. At the Grand Coulee switchyards, power is delivered to the Bonneville Power Administration (BPA), the distribution and marketing agency for federally produced power in the region. Power produced at the Grand Coulee Dam provides a significant share of the power requirements of the Pacific Northwest.

2.2 Columbia Basin Project

The Grand Coulee Dam serves multiple purposes including irrigation, electric power generation, flood control, and recreation. Six pump/generators at the dam site lift Lake Roosevelt water to irrigation facilities that lay south of the river (They may also be used to generate power during peak demand periods.). Other principle reservoirs in the system are Banks Lake, with a total storage capacity of 1,275,000 acre-feet, and Potholes Reservoir with a total storage capacity of 512,000 acre-feet.

The extensive irrigation works of the Columbia Basin Project extend southward on the Columbia Plateau 125 miles to the vicinity of Pasco, Washington, where the Snake and Columbia Rivers join (see Figure 2). The project's irrigation works are designed to deliver a full water supply to a little over 1 million acres of land, about half of which is currently served. The CBP's water distribution system includes 333 miles of main canals, 1,959 miles of laterals, and 2,761 miles of drains and wasteways.

The project command area serves three main irrigation districts-the Quincy-Columbia Basin Irrigation District (the "Quincy district"), the East Columbia Basin Irrigation District (the "East district"), and the South Columbia Basin Irrigation District (the "South District"). All basic irrigation facilities applicable to the three districts are operated and maintained by the districts themselves. The irrigation districts also reimburse the Bureau of Reclamation for that portion of the operation and maintenance costs of Grand Coulee Dam facilities used to provide irrigation water to project farms.