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Temperance Flat Dam is a proposed dam project on the San Joaquin River west of Auberry, California. The dam's main purpose would be to supplement storage capacity in the upper San Joaquin River basin. Under the current proposal, Temperance Flat would slightly more than double water storage on the San Joaquin River from below Friant Dam.〔List of dams and reservoirs in California〕 The project is highly controversial because it would flood scenic canyons and historic sites along the San Joaquin River, and impact upstream hydroelectricity generation. The Bureau of Reclamation estimates the construction costs will be between $2.5 billion and $2.6 billion, while other estimates range from US$2.96 billion up to US$3.35 billion. At 665 feet, Temperance Flat Dam would be the second highest dam in California, and the fifth tallest dam in the United States.〔http://www.water.ca.gov/swp/facilities/Oroville/LakeDam.cfm〕 On February 28, 2014, Representative Jim Costa (D-CA) introduced H.R. 4127, to authorize construction of the Temperance Flat Dam.〔http://beta.congress.gov/bill/113th-congress/house-bill/4127〕 The Bureau of Reclamation released a draft environmental impact statement for the project in September 2014. The dam is one of three major storage projects that could be funded by a $7.5 billion water bond open for voting in November 2014. ==Specifications and benefits== The U.S. Bureau of Reclamation, which would be responsible for construction and operation of Temperance Flat, previously had proposed three potential dam sites along the San Joaquin River – at river mile (RM) 274 (RKM 441), RM 279 (449), and RM 286 (RKM 460). A dam at any of these sites would be either of rockfill, concrete gravity or concrete arch design, ranging in height from , with their reservoirs ranging in size from . However, since the RM 274 and RM 279 sites are located in the upper reaches of Millerton Lake, the reservoir of Friant Dam, some of the water in their reservoirs would replace the existing storage in Millerton instead of adding new capacity. In addition, most of the previously proposed reservoir heights would flood the upstream Kerckhoff Lake. As of January 2014, the Bureau of Reclamation has limited the proposed dam to RM 274, with four alternatives on the specifics of the project.〔 The Bureau of Reclamation estimates that the annual net benefit for California of this proposed dam will range from a cost of $22.7 million to a benefit of $41 million, with an average benefit of $14.2 million for all proposed alternative plans. Annual operations and management costs would be between $16.7 and 25.1 million. The average cost-benefit ratio for California across all the alternatives is 1.12, which is reached after spreading the costs of construction over 100 years. Without including the highly subjective ecosystem benefits, the highest cost-benefit ratio is 0.83. At the 6-county level, the ratio when including the ecosystem benefits is at most 0.87.〔 The methods used to calculate environmental benefits are not readily available online.〔http://www.usbr.gov/mp/sccao/storage/docs/index.html〕 As the Temperance Flat Reservoir would inundate several existing hydroelectric powerhouses, the most recent proposal for the dam has a larger hydroelectric capacity of 160 MW.〔 Temperance Flat would allow the San Joaquin River reservoir system to capture significant amounts of winter and spring runoff that would otherwise be spilled downstream because of insufficient storage capacity. Estimates range from of water conserved each year. By increasing the surface water yield from the San Joaquin River, the dam and reservoir would help reduce the need for groundwater extraction in the San Joaquin Valley for irrigation. The Bureau of Reclamation estimates that after construction of the dam the long-term average increase in spring-run chinook salmon abundance would vary from between 0.65% and 2.7% (averaged across all four alternatives, for worst case and best case smolt-to-adult return rates, respectively). 25% of the scenarios decreased long-term chinook salmon abundance.〔 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「Temperance Flat Dam」の詳細全文を読む スポンサード リンク
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