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The Grand Ditch, also known as the Grand River Ditch and originally known as the North Grand River Ditch, is a water diversion project in the Never Summer Mountains, in northern Colorado (United States). It is long, wide, and deep on average. Streams and creeks that flow from the highest peaks of the Never Summer Mountains are diverted into the ditch, which flows over the Continental Divide at La Poudre Pass at , delivering the water into the Cache La Poudre River for eastern plains farmers. The ditch was started in 1890 and wasn't completed until 1936. The ditch diverts between 20 to 40% of the runoff from the Never Summer Mountains, and delivers an average of . It significantly impacts the ecology in the valley below〔Effects of the Grand Ditch, National Park Services, 2004. http://www.nps.gov/romo/downloads/CDRLC/summaries/ditch.pdf〕 and the National Park Service has fought in court to reduce the amount of diverted water. ==History== The Grand Ditch was built by the Larimer County Ditch Company, mostly by Japanese crews, working with hand tools and black powder. The first diverted water flowed east across La Poudre Pass on October 15, 1890. Water Supply and Storage Company took over ownership in 1891.〔''Water across the Divide'', in ''High Country News'', October 12, 2009, http://www.hcn.org/issues/41.17/water-across-the-divide〕 The ditch was extended every year, and reached three miles in 1894. After the creation of Rocky Mountain National Park, increasing demand for water led to the creation of Long Draw Reservoir, and the required land was taken away by Congress from the park in 1923. Long Draw reservoir opened in 1930. The Grand Ditch was then lengthened one more time—this also required an act of Congress since it was now in a national park—to in September 1936.〔 In May 2003 a 100-foot section of the ditch breached about south of La Poudre Pass, causing the water to cascade down the slopes and into the Colorado River. The flood left a visible scar on the mountainside: 20,000 trees were downed and 47,600 cubic yards of debris ended up in the Lulu Creek and the headwaters of the Colorado River. The Water Supply and Storage Company reached a settlement to pay $9 million in damages to Rocky Mountain National Park. Periodic overflows of the ditch, of which the 2003 flood was but one example, has left debris all over the western side of the valley; the eastern side is not affected. The Grand River Ditch was listed on the National Register of Historic Places on September 29, 1976.〔 It can be hiked starting from the Bowen/Baker Trailhead in Rocky Mountain National Park. 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「Grand Ditch」の詳細全文を読む スポンサード リンク
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