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Grand Coulee Dam is a gravity dam on the Columbia River in the U.S. state of Washington built to produce hydroelectric power and provide irrigation water. It was constructed between 1933 and 1942, originally with two power plants. A third power station was completed in 1974 to increase its energy production. It is the largest electric power-producing facility in the United States.〔(【引用サイトリンク】 publisher = U.S. Department of Energy: Energy Information Administration )〕 The proposal to build the dam was the focus of a bitter debate during the 1920s between two groups. One wanted to irrigate the ancient Grand Coulee with a gravity canal and the other supported a high dam and pumping scheme. Dam supporters won in 1933, but for fiscal reasons the initial design was for a "low dam" high which would generate electricity, but not support irrigation. The U.S. Bureau of Reclamation and a consortium of three companies called MWAK (Mason-Walsh-Atkinson Kier Company) began construction that year. After visiting the construction site in , President Franklin Delano Roosevelt began endorsing the "high dam" design which, at high, would provide enough electricity to pump water to irrigate the Columbia Basin. The high dam was approved by Congress in 1935 and completed in 1942; the first water over-topped its spillway on of that year. Power from the dam fueled the growing industries of the Northwest United States during World War II. Between 1967 and 1974, the Third Powerplant was constructed. The decision to construct the additional facility was influenced by growing energy demand, regulated river flows stipulated in the Columbia River Treaty with Canada and competition with the Soviet Union. Through a series of upgrades and the installation of pump-generators, the dam now supplies four power stations with an installed capacity of 6,809 MW. As the center-piece of the Columbia Basin Project, the dam's reservoir supplies water for the irrigation of . The reservoir is called Franklin Delano Roosevelt Lake, named after the United States President who presided over the authorization and completion of the dam. Creation of the reservoir forced the relocation of over 3,000 people, including Native Americans whose ancestral lands were partially flooded. The dam has also blocked the migration of salmon and other fish upstream to spawn. ==Background== The Grand Coulee is an ancient river bed on the Columbia Plateau created during the Pliocene Epoch (Calabrian) by retreating glaciers and floods. Originally, geologists believed the Grand Coulee was formed by a glacier diverting the Columbia River but it was revealed in the mid-late 20th century that massive floods from Lake Missoula carved most of the gorge. The earliest known proposal to irrigate the Grand Coulee with the Columbia River dates to 1892, when the ''Coulee City News'' and ''The Spokesman Review'' reported on a scheme by a man named Laughlin McLean to construct a dam across the Columbia River, high enough that water would back up into the Grand Coulee. A dam that size would have its reservoir encroach into Canada, which would violate treaties. Shortly after the Bureau of Reclamation was founded, it investigated a scheme for pumping water from the Columbia River to irrigate parts of central Washington. An attempt to raise funds for irrigation failed in 1914, as a bond measure was rejected by Washington voters. A lawyer from Ephrata, Washington, named William M. Clapp proposed in 1917 that the Columbia be dammed immediately below the Grand Coulee. He suggested a concrete dam could flood the plateau, just as nature blocked it with ice centuries ago. Clapp was joined by James O'Sullivan, another lawyer, and by Rufus Woods, publisher of the ''Wenatchee World'' newspaper. Together, they became known as the "Dam College". Woods began promoting the Grand Coulee Dam in his newspaper, often with articles written by O'Sullivan. The dam idea gained popularity with the public in 1918. Backers of reclamation in Central Washington split into two camps. One side, known as the "pumpers", favored a dam with pumps to elevate water from the river into the Grand Coulee from which canals and pipes could be used to irrigate farmland. The other side, known as the "ditchers", favored diverting water from northeast Washington's Pend Oreille River via a gravity canal to irrigate farmland in Central and Eastern Washington. Many locals such as Woods, O'Sullivan and Clapp were pumpers, while many influential businessmen in Spokane associated with the Washington Water and Power Company (WWPC) were staunch ditchers. The pumpers argued that hydroelectricity from the dam could be used to cover costs and claimed the ditchers sought to maintain a monopoly on electric power.〔 The ditchers took a number of steps to ensure support for their proposals. In 1921, WWPC secured a preliminary permit to build a dam at Kettle Falls, about upstream from the Grand Coulee. If built, the Kettle Falls Dam would have lain in the path of the Grand Coulee Dam's reservoir, essentially blocking its construction. WWPC planted rumors in the newspapers, incorrectly stating that exploratory drilling at the Grand Coulee site found no granite on which a dam's foundations could rest, only clay and fragmented rock. This was later disproved with Reclamation-ordered drilling. Ditchers hired General George W. Goethals, engineer of the Panama Canal, to prepare a report. Goethals visited the state and produced a report backing the ditchers. The Bureau of Reclamation was unimpressed by Goethals' report, believing it filled with errors.〔 In , President Warren G. Harding visited Washington state and expressed support for irrigation work there, but died a month later. His successor, Calvin Coolidge, had little interest in irrigation projects. The Bureau of Reclamation, desirous of a major project that would bolster its reputation, was focusing on the Boulder Canyon Project that resulted in the Hoover Dam. Reclamation was authorized to conduct a study in 1923, but the project's cost made federal officials reluctant. The Washington state proposals received little support from those further east, who feared the irrigation would result in more crops, depressing prices. With President Coolidge opposed to the project, bills to appropriate money for surveys of the Grand Coulee site failed. In 1925, Congress authorized a U.S. Army Corps of Engineers study of the Columbia River. This study was included in the Rivers and Harbors Act of , which provided for studies on the navigation, power, flood control and irrigation potential of rivers. In , the Army Corps responded with the first of the "308 Reports" named after the 1925 House Document No. 308 (69th Congress, 1st Session). With the help of Washington's Senators, Wesley Jones and Clarence Dill, Congress ordered $600,000 in further studies to be carried out by the Army Corps and Federal Power Commission on the Columbia River Basin and Snake Rivers. U.S. Army Major John Butler was responsible for the upper Columbia River and Snake River and in 1932, his 1,000-page report was submitted to Congress. It recommended the Grand Coulee Dam and nine others on the river, including some in Canada. The report stated that electricity sales from the Grand Coulee Dam could pay for construction costs. Reclamation—whose interest in the dam was revitalized by the report—endorsed it.〔 Although there was some support for the Grand Coulee Dam, others argued there was little need for more electricity in the Northwest and crops were in surplus. The Army Corps did not believe construction should be a federal project and saw low demand for electricity. Reclamation argued that energy demand would rise by the time the dam was complete. The head of Reclamation, Elwood Mead, stated he wanted the dam built no matter the cost. President Franklin D. Roosevelt, who took office in March, 1933, supported the dam because of its irrigation potential and the power it would provide, but he was uneasy with its price tag. For this reason, he supported a "low dam" instead of the "high dam". He provided in federal funding, while Washington State provided $377,000.〔 In 1933, Washington governor Clarence Martin set up the Columbia Basin Commission to oversee the dam project, and Reclamation was selected to oversee construction.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Grand Coulee Dam」の詳細全文を読む スポンサード リンク
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