Laserfiche WebLink
<br />lr. <br />N <br />tC <br />~ <br /> <br />c <br /> <br />12. Authorization. --Construction of Hoover Dam was authorized by <br />the Swing-Johnson Bill (Boul.der Canyon Project Act), which was passed <br />by Congress on 21 December 1928. The Boul.der Canyon Project Act states <br />that Boul.der Dam and the reservoir that it creates shall be used: <br />first, for river regulation, improvement of navigation, and flood <br />controlj second, for irrigation and domestic uses; and third, for <br />power. Public Law 43, approved by Congress on 30 April 1947, changed <br />the name of the structure from Boul.der Dam to Hoover Dam. The Bureau <br />of Reclamation began construction of Hoover Dam in January 1931 and <br />completed construction in February 1935. The first power was generated <br />in September 1936. <br /> <br />{~~) <br /> <br />13. Overall project.--Hoover Dam is a multiple-purpose, concrete <br />thick-arch dam. Its structural height of 726.4 feet makes it one of <br />the world's highest dams. Lake Mead, the reservoir formed behind <br />Hoover Dam has a 1.ength of ll5 m11es and a gross capacity of 29,755,000 <br />acre-feet (1963-64 survey estimate) st elevation 1,229 feet, the top of <br />the flood-control pool. The spillwsy works consist of 2 side-channel <br />spillways with each spillway crest adjustable between elevation 1,205.4 <br />feet and 1,221.4 feet by means of 4 automatic drum gates, each 100 by <br />16 feet. The capacity of both spillways is 400,000 cubic feet per <br />aecond with gates depressed and reservoir water surface at elevation <br />1,232 feet, top of dam. The outlet worka originate at 4 intake towers, <br />which are located near the upstream face of the dam. A 30-foot-diameter <br />steel pipe connects each intake Wlit to the downstream outlet works, <br />which consist, of 6 needle valves and 6 emergency gates for each complete <br />Wlit. The 30-foot-diameter pipe, after cOnnection with the powerhouse <br />by four 13-foot-diameter penstocks, is reduced to 25 feet diameter. The <br />two lower out1.et units are equipped with 72-inch needle valves; and the <br />upper Wlits with 84-inch valves. The current out1.et installation con- <br />sists of e1.even 84-inch canyon-wall needle valves and twelve 72-inch tunnel- <br />plug valves having a combined capacity of 86,100 cubic feet per second <br />with the water surface at elevation 1,229, top of flood-control pool. <br />The power-plant installation is composed of 19 generating Wlits having <br />a capacity of 1,,344,800 kilowatts. The power penstocks can pass a max1lllum <br />of 33,600 cubic feet per second with the water surface at e1.evation 1,229. <br />Operating experience indicates that the maximum average daily re1.ease <br />through the power plant is f3IYI, of the maxiDlUlll hourly re1.ease. Therefore, <br />the total maximum practical outlet release (23 needle valves plus 80 <br />percent of the maximum hourly release through the power penstocks) is <br />113,000 cubic feet per second. A tabulation of pertinent data for Hoover <br />Dam and Lake Mead is given on pages i11 and iv. <br /> <br />14. Four major dams have been constructed upstream of Hoover <br />Dam under the Colorado River Storage Project. They are Glen Canyon <br />Dam on the Colorado River, Navajo Dam on the San Juan River, Blue <br />Mesa Dam on the Gunnison River, and FlaJDing Gorge Dall! on the Green <br />\ <br /> <br />\ <br /> <br />4 <br />