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The New Croton Dam (also known as Cornell Dam),〔 part of the New York City water supply system, stretches across the Croton River near Croton-on-Hudson, New York, about north of New York City. Construction began in 1892 and was completed in 1906.〔("The Croton Dam" ). Village of Croton-on-Hudson Historical Society. Retrieved on July 8, 2007.〕 Designed by Alphonse Fteley (1837–1903), this masonry dam is broad at its base and high from base to crest. Its foundation extends below the bed of the river, and the dam contains of masonry.〔("The Opening of the New Croton Reservoir" ). Yorktown Historical Society. Retrieved on July 11, 2007.〕 The engineers' tablet mounted on the headhouse nearest the spillway lists the spillway length as and the total length of the dam and spillway combined as .〔Tompkins, Christopher R: ''The Croton Dams and Aqueduct'', page 2. Arcadia Publishing, 2000. ISBN 0-7385-0455-6.〕 At the time of its completion, it was the tallest dam in the world.〔Jackson, Donald C: ''Great American Bridges and Dams'', page 128. John Wiley and Sons, 1988. ISBN 0-471-14385-5〕 New Croton Dam impounds up to of water, a small fraction of the New York City water system's total storage capacity of .〔("New Croton" ). New York City Department of Environmental Protection. Retrieved on July 10, 2007.〕 The dam, in Westchester County, has an unusual spillway, part artificial and part natural, which forms a waterfall on the north side of the structure. New Croton Dam has a public park and trail head at its base and a road along its crest. Road use is limited to pedestrians and emergency vehicles. == History == The original Croton Dam (Old Croton Dam) was built between 1837 and 1842 to improve New York City's water supply. By 1881, after extensive repairs to the dam, which was high, Old Croton Reservoir was able to supply about a day to the city via the Old Croton Aqueduct.〔("NYC Water Supply Watersheds: History" ). New York City Department of Environmental Protection. Retrieved on July 11, 2007.〕 To meet escalating water needs, the Aqueduct Commission of the City of New York ordered construction of a new Croton system in 1885. Hydro engineer James B. Francis was brought in as a consultant for the construction. The proposed dam and reservoir were to cover 20 square miles (51.8 km²) of land occupied by public and private buildings, six cemeteries, and more than 400 farms.〔( "The Croton Dam" ). Village of Croton-on-Hudson Historical Society. Retrieved on July 8, 2007.〕 Condemnation disputes led to "protests, lawsuits, and confusion" before payment of claims and the awarding of construction contracts.〔 The work force on the new dam included stonemasons and laborers who had worked on the original dam. John B. Goldsborough, superintendent of excavations and hiring for the project, also recruited stonemasons from southern Italy, who re-located to New York. Work began in 1892 at a site on the property of A.B. Cornell〔(【引用サイトリンク】url=http://www.ascemetsection.org/content/view/341/875/ )〕 four miles (6.4 km) downstream of the original dam, which was submerged by the new reservoir. New Croton Reservoir was eventually able to supply a day via a new aqueduct that carried water to Jerome Park Reservoir in the north Bronx, New York City.〔("History and Geology of the NYC Aqueduct System" ). Merguerian, Charles. (Notes for October 4, 2000, lecture at the Long Island Geologists Dinner Meeting). Retrieved on July 8, 2007.〕 Building the dam meant diverting the river from its normal path and pumping the riverbed dry. To accomplish this, workers dug a crescent-shaped canal long and wide in the hill on the north side of the river, secured the canal with a masonry retaining wall, and built temporary dams to control the water flow.〔 The initial construction lasted eight years, and extensive modifications and repairs went on for another six. Working conditions were often difficult. A silent film, ''The Croton Dam Strike'', released in 1900, depicted labor–management problems related to the dam's construction.〔(【引用サイトリンク】 publisher = Internet Movie Database )〕 The bridge over the spillway was replaced in 1975 and again in 2005. In that same year, because of the September 11 attacks on New York City, the New York City Department of Environmental Protection proposed permanent closure of the road across the top of the dam. Pedestrians and emergency vehicles were allowed to use New Croton Dam Road, but all other traffic was re-routed. The department made plans to replace temporary vehicle barriers with permanent barriers after completion of a New Croton Dam Rehabilitation Project in 2011. 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「New Croton Dam」の詳細全文を読む スポンサード リンク
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