|
}} The Elwha Dam was a 108-ft (33 m) high dam located in the United States, in the state of Washington, on the Elwha River approximately upstream from the mouth of the river on the Strait of Juan de Fuca. The Elwha River Ecosystem and Fisheries Restoration Act of 1992 authorized the US Federal Government to acquire the Elwha Dam and Glines Canyon Dam hydroelectric power projects for decommissioning and demolition for habitat restoration. Removal of the Elwha Dam began in September 2011 and was fully complete by March 2012, allowing the Elwha River to flow freely through the site. == Construction == The dam was built under the direction of Thomas Aldwell. Aldwell previously bought up tracts of land around the river, and with the help of Canadian financier George Glines, began construction of the Elwha Dam in 1910. Aldwell and his contractors cut corners on constructing the dam, including not building fish passages and did not secure it to the bedrock. Thus, in 1912, as the reservoir filled behind the nearly completed dam, the lower sections of the dam gave way and a torrent of water headed downstream, taking out a bridge. Aldwell was able to get funding for reconstructing the dam and it was completed in 1913. The reservoir that filled the valley behind was known as Lake Aldwell. The dam was listed on the National Register of Historic Places in 1988.〔(【引用サイトリンク】 title=National Register of Historical Places record for Elwha River Hydroelectric Power Plant )〕 Initially, along with the Glines Canyon Dam, which was completed in 1926, it helped to fuel economic growth and development for the Olympic Peninsula and the community of Port Angeles, Washington. However, by the early 21st Century, the combined power output of both dams only provided the equivalent of 38% of the electricity needed to operate one paper mill, the Daishowa America mill. Lacking passage for migrating salmon, its construction blocked access by anadromous salmonids to the upper 38 miles (48 km) of mainstem habitat and more than of tributary habitat. The salmon runs that once numbered more than 400,000 adult returns in over of available habitat, now numbered less than 4,000 adult returns on only of available habitat. 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「Elwha Dam」の詳細全文を読む スポンサード リンク
|