|
The Bull Run Hydroelectric Project was a Portland General Electric (PGE) development in the Sandy River basin in the U.S. state of Oregon. Originally built between 1908 and 1912 near the town of Bull Run, it supplied hydroelectric power for the Portland area for nearly a century, until it was removed in 2007 and 2008. The project used a system of canals, tunnels, wood box flumes and diversion dams to feed a remote storage reservoir and powerhouse. The entire project was removed because of rising environmental costs. Marmot Dam on the Sandy River was demolished in 2007, and the Little Sandy Dam on the Little Sandy River was taken down in 2008. ==History and overview== The Mount Hood Railway and Power Company (MHR&P), also known as the Mount Hood Company, began the project in 1906, building the Little Sandy Dam to divert water through a wooden flume, about long, to Roslyn Lake.〔Taylor, pp. 21–22〕 The dam reduced streamflows on the lower of the Little Sandy River and blocked all salmon and steelhead access to the upper of the river.〔 Roslyn Lake was at above sea level, about higher than the mouth of the Bull Run River, at . The lake acted as a reservoir for the powerhouse, which was completed and put into operation in 1912, the same year that the MHR&P merged with Portland Railway, Light and Power Company (PRL&P), the predecessor of PGE.〔 In 1913 PRL&P built a dam on the Sandy River to supplement the Little Sandy Dam. The Marmot Dam, high, diverted water from the Sandy to the Little Sandy by canal and tunnel, the longest of which ran under the ridge between the two rivers. The new dam supplied up to to the Little Sandy above its diversion dam, and the Little Sandy provided up to , all of which could be diverted through the flume to Roslyn Lake.〔 The Marmot Dam included a fish ladder to allow migration of salmon and steelhead; however it performed poorly at first and required frequent upgrades and maintenance, which continued into the 1990s. To prevent fish from being swept into the diversion canal, PGE installed fish screens in 1951 and later added a bypass system to rescue fish trapped in the canal.〔Taylor, pp. 22–24〕 In 1989 the original timber crib Marmot Dam was replaced with a concrete structure. 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「Bull Run Hydroelectric Project」の詳細全文を読む スポンサード リンク
|