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Columbia Basin Irrigation System: nearly 60 years of feeding Washington
Dates: 1933-1941; 1946-1983
Imagine coming to Eastern Washington in 1890 and finding wide open spaces -- but little rainfall and no way to harness water from the raging river below.
One hundred years later, more than 300 miles of canals irrigate over 600,000 acres with water from the Columbia River.
In the 1930s, the U.S. Department of Reclamation began to study ways to irrigate land in the Big Bend of the Columbia River from the Spokane River in the north to Pasco in the south. Farmers had tried before, using gas-powered pumps to pull water from underground wells and even wind mills to bring water uphill from the river.
In 1917, Ephrata attorney William "Billy" Clapp proposed building a dam on the Columbia at the Grand Coulee, a far-fetched idea at the time.
In 1927, the Senate authorized funds for the U.S. Army Corps of Engineers to survey the Columbia for potential dam sites. The Corps found that building a dam would cost less than a gravity canal, and would generate funds from power sales.
The Corps soon found building the dam in two phases would be difficult and expensive, and Congress authorized construction of a 550-foot dam at Grand Coulee. The massive concrete structure, 5,223 feet long and containing more than 11 million cubic yards of concrete, was finished in 1941.
Irrigation took a back seat during World War II, with attention turned toward generating power for the war effort. It wasn't until 1946 that construction continued on the pumping plant, and irrigation service didn't begin until June 1952.
Six 65,000-horsepower pumps delivered water from Roosevelt Lake, the reservoir of the Grand Coulee Dam, up 280 feet into a concrete-lined feeder canal, sending water into Banks Lake above. Six more pumps were added in 1973, with the luxury of being reversible for use as generators.
The 1.8-mile feeder canal can carry 16,000 cubic feet of water per second, flowing into Banks Lake, named for Grand Coulee Dam's chief construction engineer, Frank A. Banks.
Two earth dams hold 1,275,000 acre-feet of water, with 715,000 acre-feet available for irrigation. The water flows from Dry Falls Dam to the 21-mile Main Canal, through the 12,038-foot-long Bacon Siphon, into the Bacon Tunnel and over the 165-foot Summer Falls into Billy Clapp Lake.
South of the lake, water flows to the bifurcation works where it is divided into two branches. The East Low Canal flows 87 miles down the eastern edge of the project area into the Scooteney Reservoir. The West Canal flows past Soap Lake, crossing the Lower Grand Coulee via the Soap Lake Siphon and ending near Lower Goose Lake.
In the center of the project lands, O'Sullivan Dam holds the return flows from the farms and drainage systems in the Potholes Reservoir, until it flows along the Potholes Canal, parallel to the East Low Canal, to the Scooteney Reservoir.
In 1996, 622,053 acres were irrigated by the series of canals, laterals, siphons and drains.
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