Grand Lake (Colorado)

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Grand Lake
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Grand Lake
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Grand Lake
Location Grand County, Colorado
Coordinates 40°14′42″N105°48′58″W / 40.24500°N 105.81611°W / 40.24500; -105.81611 Coordinates: 40°14′42″N105°48′58″W / 40.24500°N 105.81611°W / 40.24500; -105.81611
Lake type Glacial Lake
Catchment area Native inflows come from the Continental Divide through Rocky Mountain National Park.
Basin  countriesUnited States
Max. length1.5 mi (2.4 km) [1]
Max. width1 mi (1.6 km) [1]
Surface area 507 acres (205 ha) [2]
Max. depth389 ft (119 m) [2]
Water volume 68,621 acre⋅ft (84,643,000 m3) [2]
Shore length14 mi (6.4 km) (approx) [3]
Surface elevation8,367 ft (2,550 m)
Settlements Grand Lake, Colorado
1 Shore length is not a well-defined measure.

Grand Lake is Colorado's largest and deepest natural lake. [4] It is located in the headwaters of the Colorado River in Grand County, Colorado. On its north shore is located the historic and eponymous town of Grand Lake. The lake was formed during the Pinedale glaciation, which occurred from 30000 BP (before present) to 10000 BP. [5] The glacial terminal moraine created a natural dam. Natural tributaries to the lake are the North Inlet and East Inlet, both of which flow out of Rocky Mountain National Park, which surrounds the lake on three sides. Grand Lake is located 1 mile from the Park's western entrance. Grand Lake was named Spirit Lake by the Ute Tribe because they believed the lake's cold waters to be the dwelling place of departed souls.

Contents

Colorado-Big Thompson Project

As part of the Colorado-Big Thompson Project, Grand Lake forms a continuous body of water with the man-made reservoir Shadow Mountain Lake, which under natural conditions then flows into another man-made reservoir, Lake Granby. The elevation of Grand Lake is maintained between 8,367 feet (2,550 meters) and 8,366 feet (2,549.8 meters). When the Colorado-Big Thompson (C-BT) project is diverting water to northeastern Colorado, water collected in Lake Granby can be pumped back into Shadow Mountain where it flows backward into Grand Lake, then under Rocky Mountain National Park and the Continental Divide via the Alva B. Adams Tunnel to the Big Thompson River on the eastern slope of the Rocky Mountains. From there, the water flows into the South Platte River and is used for agriculture, municipal, and industrial purposes. Diverted C-BT water provides hydroelectric power to five power stations on the eastern slope of the Colorado Rockies.

The C-BT is one of the first of many large-scale diversions of water from the Colorado River Basin between Colorado and the Gulf of California. Because the C-BT Project moves water from the Colorado Basin to the South Platte Basin (on a larger scale, from the Colorado River, which drains to the Gulf of California, to the Mississippi River, which drains to the Gulf of Mexico), the project is considered a transbasin diversion.

Photo of Grand Lake taken in 2018 Grand Lake, Colorado, Rainbow.jpg
Photo of Grand Lake taken in 2018

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Big Thompson River

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Middle Park (Colorado basin)

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Horsetooth Reservoir

Horsetooth Reservoir is a large reservoir in southern Larimer County, Colorado, in the foothills just west of the city of Fort Collins, Colorado. The reservoir runs north-south for approximately 6.5 miles (10 km) and is approximately one-half mile (1 km) wide. Its shape and orientation are the result of the fact that the main body of the reservoir is contained between several hogback ridges. The Dakota Hogback runs along the east side where gaps in the ridge are plugged by dams. On the west (uphill) side there are two prominent ridges topped by erosion-resistant sandstones of the Lyons and Ingleside formations. Gaps in these ridges have created a handful of bays and coves the largest of which is Inlet Bay, home to a marina and campgrounds.

Colorado-Big Thompson Project

The Colorado-Big Thompson Project is a federal water diversion project in Colorado designed to collect West Slope mountain water from the headwaters of the Colorado River and divert it to Colorado's Front Range and plains. In Colorado, approximately 80% of the state's precipitation falls on the West Slope, in the Rocky Mountains, while around 80% of the state's growing population lives along the East Slope, between the cities of Fort Collins and Pueblo.

Shadow Mountain Dam Dam in Grand County, near Granby, Colorado, USA

Shadow Mountain Dam is a zoned earth-fill dam on the Colorado River in Grand County, Colorado. Constructed between 1944 and 1946, the Shadow Mountain Dam creates the Shadow Mountain Lake, with a structural height of 63 feet (19 m) and a drainage area of 187 square miles (480 km2). Shadow Mountain Lake is a holding reservoir for water pumped up from Lake Granby just to the south through the Granby Pumping Plant and Canal. Shadow Mountain Lake is connected by a short channel to the natural Grand Lake. The west portal of the Alva B. Adams Tunnel is located on Grand Lake. The Adams Tunnel diverts west slope water to the east slope of the Rocky Mountains for use in agriculture and to serve the populated areas of Colorado, including Denver.

Granby Dam Dam in Grand County, near Granby, Colorado, USA

Granby Dam is an earthfill dam that dams the Colorado River 5.5 miles (8.9 km) northeast of Granby, Colorado in Grand County, Colorado. This 298-foot (91 m)-tall dam was constructed between 1941 and 1950 and has a drainage area of 311 square miles (810 km2). The Granby Dam's reservoir is known as Lake Granby, the largest reservoir component of the Colorado-Big Thompson Project. Lake Granby stores Colorado River water that is diverted under the Continental Divide for agriculture and municipal use within north-eastern Colorado including the cities of Boulder, Fort Collins, Loveland, and Greeley. In addition to the waters of the Colorado, water from Willow Creek just below the dam is pumped up 175 feet (53 m) to Lake Granby. Water from Lake Granby is pumped 125 feet (38 m) higher by the Granby Pumping Plant to the Granby Pump Canal, which extents 1.8 miles (2.9 km) to Shadow Mountain Lake, from which water is diverted through the Alva B. Adams Tunnel to the East Slope.

Fryingpan-Arkansas Project

The Fryingpan-Arkansas Project, or "Fry-Ark," is a water diversion, storage and delivery project serving southeastern Colorado. The multi-purpose project was authorized in 1962 by President Kennedy to serve municipal, industrial, and hydroelectric power generation, and to enhance recreation, fish and wildlife interests. Construction began in 1964 and was completed in 1981. The project includes five dams and reservoirs, one federal hydroelectric power plant, and 22 tunnels and conduits totaling 87 miles (140 km) in length. The Bureau of Reclamation, under the Department of the Interior built and manages the project.

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Lake Granby

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Green Mountain Reservoir Dam in Summit County, Colorado

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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 Front Range of Colorado. It is 13.1 miles (21.1 km) long, with a concrete lined diameter of 9.75 feet (2.97 m). The tunnel drops 109 feet (33 m) in elevation along its length and runs in a straight line under the Continental Divide from west to east, passing under Rocky Mountain National Park. At its deepest point, the tunnel is about 3,800 feet (1,200 m) below the surface of the mountain peaks. Construction began on 15 June 1940, but was suspended as a result of World War II priorities, from the end of 1942 to August 1943. The tunnel was holed through on 31 March 1944, an event that was broadcast throughout the United States by NBC Radio. The tunnel was posthumously named for its chief advocate, US Senator Alva B. Adams.

Course of the Colorado River

The Colorado River is a major river of the western United States and northwest Mexico in North America. Its headwaters are in the Rocky Mountains where La Poudre Pass Lake is its source. Located in north central Colorado it flows southwest through the Colorado Plateau country of western Colorado, southeastern Utah and northwestern Arizona where it flows through the Grand Canyon. It turns south near Las Vegas, Nevada, forming the Arizona–Nevada border in Lake Mead and the Arizona–California border a few miles below Davis Dam between Laughlin, Nevada and Needles, California before entering Mexico in the Colorado Desert. Most of its waters are diverted into the Imperial Valley of Southern California. In Mexico its course forms the boundary between Sonora and Baja California before entering the Gulf of California. This article describes most of the major features along the river.

Northern Colorado Water Conservancy District

The Northern Colorado Water Conservancy District — more commonly referred to as Northern Water — is a water utility for eight counties in northeastern Colorado. Northern Water works with the Colorado-Big Thompson Project to transfer water from the Colorado Western Slope over the Continental Divide for agricultural, industrial, and municipal water supply in northeastern Colorado. The District's offices are in Berthoud, Colorado.

References

  1. 1 2 "Grand Lake Winter Adventure Tour".
  2. 1 2 3 Lieberman, D.M. 2008. Physical, Chemical, and biological Attributes of Western and Eastern Slope Reservoir, Lake, and Flowing Water sites on the Colorado-Big Thompson Project 2005-2007: Lake Granby, Grand Lake, Shadow Mountain Reservoir, Horsetooth Reservoir, Carter Lake. Denver Colorado: Department of Interior, University of Colorado Marine Science & Chondrichthyes Studies, Bureau of Reclamation; 469p
  3. Grand County Government
  4. Pennak, R.W. 1955 Comparative Limnology of Eight Colorado Mountain Lakes. University of Colorado Studies, Series in Biology 2:1-71, Boulder, CO 1955
  5. "Grand Lake".