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Gibraltar Dam is located on the Santa Ynez River, in Santa Barbara County, California, in the United States. Forming Gibraltar Reservoir, the dam is owned by the city of Santa Barbara and its primary purpose is municipal water supply. The dam and reservoir provide about to Santa Barbara each year, supplying 29.4% of the city's water. Completed in 1920 just above Devils Canyon, about north of Santa Barbara across the Santa Ynez Mountains, the dam was originally a concrete arch structure about high, impounding a reservoir with a capacity of . Gibraltar was the first major dam built on the Santa Ynez River. Diversions from the dam greatly supplemented the flow of water through the Mission Tunnel, which was excavated in 1912 to intercept groundwater flow under the Santa Ynez Mountains and channel it south to Santa Barbara. It was not until 1922 when Gibraltar Reservoir first reached capacity. The reservoir has suffered from heavy sedimentation, and by 1948 was left with just – 53.8% of the original capacity. To address this problem the dam was raised to a height of and a new buttressed spillway section added, again increasing storage capacity to . By the early 21st century, the reservoir's capacity had been reduced to .〔 Attempts have been made to slow the rate of silting, including the construction of the Mono and Agua Caliente debris dams that together have prevented of sediment from reaching Gibraltar, but the reservoir continues to accumulate sediment at a rate of per year.〔 ==See also== *List of dams and reservoirs in California *List of lakes in California 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「Gibraltar Dam」の詳細全文を読む スポンサード リンク
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