Grand Ditch

Grand River Ditch
U.S. National Register of Historic Places
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Nearest city	Grand Lake, Colorado
Coordinates	40°27′34″N 105°51′01″W / 40.45944°N 105.85028°W / 40.45944; -105.85028
Area	460 acres (1.9 km2)
Built	1890
Engineer	J.J. Argo
MPS	Rocky Mountain National Park MRA (AD)
NRHP reference No.	76000218[1]
Added to NRHP	September 29, 1976

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 in the United States. It is 14.3 miles (23.0 km) long, 20 feet (6.1 m) wide, and 3 feet (0.91 m) 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 10,175 feet (3,101 m), delivering the water into Long Draw Reservoir^[2] and the Cache La Poudre River for eastern plains farmers. The water would otherwise have gone into the Colorado River (formerly known as the "Grand River", from which the name of the ditch is derived) that flows west towards the Pacific; instead, the Cache La Poudre River goes East and through the Mississippi River discharges into the Gulf of Mexico.

The ditch was started in 1890 and wasn't completed until 1936. The ditch diverts between 20 and 40% of the runoff from the Never Summer Mountains, and delivers an average of 20,000 acre-feet (25,000,000 m³). It significantly impacts the ecology in the valley below and the National Park Service has fought in court to reduce the amount of diverted water.^[3][4]