Shadow Mountain Lake is a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

Grand County, Colorado Grand County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 15,717. The county seat is Hot Sulphur Springs. History When Grand County was created February 2, 1874 it was carved out of Summit C ...

, near the headwaters of the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...

. Shadow Mountain Lake is created by Shadow Mountain Dam. The lake forms a continuous body of water with Grand Lake, the largest natural lake in Colorado; they are separated by gates. Shadow Mountain Lake is part of Arapaho National Recreation Area. The creation of Shadow Mountain Lake was authorized by the Colorado-Big Thompson bill, passed in 1937,Carl Ubbelohde, Duane A. Smith, Maxine Benson, ''A Colorado History'', Pruett Publishing, 2006, , page 308 which also created the Colorado-Big Thompson Project. Water from the Grand Lake-Shadow Mountain Lake body is diverted through the

Alva B. Adams tunnel The Alva B. Adams Tunnel is the principal component of the largest transmountain water project in Colorado, the Colorado-Big Thompson Project (C-BT). The tunnel transfers water from the western slope of the Colorado River drainage to the eastern F ...

, at the eastern edge of Grand Lake, into the

Big Thompson River The Big Thompson River is a tributary of the South Platte River, approximately 78 miles (123 km) long, in the U.S. state of Colorado. Originating in Forest Canyon in Rocky Mountain National Park, the river flows into Lake Estes in the town ...

on the east side of the Continental Divide. Storage began in 1947.

Notes and references

Reservoirs in Colorado Protected areas of Grand County, Colorado Arapaho National Forest Lakes of Grand County, Colorado 1947 establishments in Colorado {{Colorado-geo-stub