Grand Lake is

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

's largest and deepest natural

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

. It is located in 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 ...

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 ...

. 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. The

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...

terminal moraine A terminal moraine, also called end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge ...

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 Ute () are the Indigenous people of the Ute tribe and culture among the Indigenous peoples of the Great Basin. They had lived in sovereignty in the regions of present-day Utah and Colorado in the Southwestern United States for many centuries unt ...

because they believed the lake's cold waters to be the dwelling place of departed souls.

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 Shadow Mountain Lake is a reservoir in Grand County, Colorado, near the headwaters of the Colorado River. Shadow Mountain Lake is created by Shadow Mountain Dam. The lake forms a continuous body of water with Grand Lake, the largest natural lake ...

, which under natural conditions then flows into another man-made reservoir,

Lake Granby Lake Granby is the third largest body of water in Colorado. It was created by the erection of Granby Dam, completed in 1950, as part of the Bureau of Reclamation's Colorado-Big Thompson Project. Water from Lake Granby is pumped via the Farr Pump ...

. 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 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 ...

to 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 eastern slope of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

. From there, the water flows into the

South Platte River The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwest and the American Southwest/ Mountain West. It ...

and is used for

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...

municipal A municipality is usually a single administrative division having corporate status and powers of self-government or jurisdiction as granted by national and regional laws to which it is subordinate. The term ''municipality'' may also mean the go ...

, and

industrial Industrial may refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems * Industrial city, a city dominate ...

purposes. Diverted C-BT water provides

hydroelectric power Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

to five

power station A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many ...

s 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 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 ...

between

and the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

. Because the C-BT Project moves water from the Colorado Basin to the South Platte Basin (on a larger scale, from the

, which drains to the

, to the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

, which drains to the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

), the project is considered a transbasin diversion. Grand Lake, Colorado, Rainbow

References

External links

U.S. Bureau of Reclamation website on Colorado-Big Thompson ProjectMap of Grand Lake Village

Grand County Water Information NetworkTown of Grand Lake HomepageGrand County Government HomepageArapaho National Recreation Area websiteColorado Historical SocietyGrand County Library District websiteGrand County Tourism Board website
* ttp://www.nps.gov/romo/ Rocky Mountain National Park website {{authority control Lakes of Colorado Lakes of Grand County, Colorado Religious places of the indigenous peoples of North America Sacred lakes Grand Lake, Colorado