The Colorado River watershed drains 244,000 square miles, 2000 in Mexico.

Twenty-five million people in seven western states (Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming), two Mexican states (Sonora and Baja California), and 32 American Indian tribal communities share Colorado River water; 30 million people receive electricity from its hydroelectric power

The river flows 1,700 miles from Wyoming’s melting glaciers and Colorado’s snow run-off and falls 14,000 feet before reaching its natural outlet, the Gulf of California

Petroglyphs on the Colorado. Courtesy of Jeremy Rowe.

There are 34 Indian tribes in the basin, 27 claim rights to use it.

Ten tribes occupy Indian reservations with rights to the Colorado River: the Chemehuevi Indian Tribe; the Cocopah Indian Community; the Colorado River Indian Tribes, the Fort Mojave Indian Tribe; the Jicarilla Apache Tribe, the Navajo Nation, the Northern Ute Tribe, the Quechan Indian Tribe of the Fort Yuma Reservation, the Southern Ute Indian Tribe, and the Ute Mountain Ute Indian Tribe.

The river carves out the Marble, Grand, Black, Boulder, Topok, and Grand Canyons.

Commerce Secretary Herbert Hoover presides over the signing of the Colorado River Compact,
Bishop's Lodge, outside Santa Fe, New Mexico, November 1922.
Courtesy of U.S. Department of Interior, Bureau of Reclamation.

The 1922 compact divided the river into two basins that get half the water flow: the upper basin includes New Mexico, Wyoming, Colorado, and Utah and the lower basin includes Arizona, California, and Nevada

Every drop of its 5 trillion gallons of water flow is apportioned

Human use of Colorado River water has approximately doubled its salinity

Arizona’s share of the Colorado River enabled large population increases in Phoenix and Tucson, which would otherwise not be able to exist

Promotion for the Kolb Brothers Studio, Grand Canyon c 1915.
Courtesy Jeremy Rowe

Six national parks and recreation areas along the Colorado shores support boating, hiking, fishing, and white water rafting

The squawfish, razorback sucker, humpback, and bonytail chub are all native endangered species of the Colorado River

The humpback chub, native to the Colorado, has a hump behind its head that contains extra muscles connecting to its tail to survive the Colorado’s occasionally torrential waters

There are over 10 major dams and 80 major diversions on the river that collectively prevent the river from reaching the Delta exceed in high flow years

In the 1920s the Colorado Delta was described as a “milk and honey wilderness.” Today it is a salt flat in many places

Hoover Dam at Night. Courtesy of Jeremy Rowe.

Hoover Dam, at 726 feet, flooded 115 miles of the Colorado River and created Lake Mead

The Grand Canyon narrowly escaped damming and flooding in the 1960s

The Glen Canyon Dam and Lake Powell flooded ten thousand Anasazi

Seventy percent of the Colorado River comes from the state of Colorado

Irrigated lands in the Bonneville Unit, Salt Lake City in the 1980s, and construction of the CUP.
Courtesy of Special Collections Department, J. Willard Marriott Library, University of Utah.

The prior appropriation doctrine of 1855 is still in force, which grants oldest water rights superiority over junior users so long as water is put to a beneficial use

In 1905 levees on the Colorado and Gila River broke and water flooded for two years, creating the Salton Sea, which is 45 miles long, 17 miles wide and 80 feet deep

Cocopa Indians along the US/Mexico border, who have depended on the river for 2,000 years, must now truck in their water because upstream conditions prevent the river from flowing to their communities

It is estimated that by 2007 Las Vegas could run out of Colorado River water

The first high dam on the Colorado was the Roosevelt Dam, on a tributary, the Salt River, in 1911

As dams began to control the river it carried less silt and more salt. Salinity tripled between 1917 and 1961

By 1964, 19 big dams controlled the river


Unger family vacation on Lake Powell.Houseboating on Lake Powell
is a major way people experience the Colorado River today.
Courtesy of the photographer, Renate Unger.

There are more than 20 storage reservoirs with capacities greater than 20,000 acre-feet in the Colorado River Basin

The two largest reservoirs are Lake Mead and Lake Powell (25.88 million and 24.32 million acre-feet respectively)

The Delta is the largest remaining wetland system in the American southwest

Photographer A. F. Messinger at teh bottom of the Grand Canyon c 1898.
Courtesy of Jeremy Rowe.

River flows to the Delta have been reduced nearly 75 percent during the 20th century. Consequences: less silt, fewer nutrients, higher salinity, higher concentrations of pollutants

The historic Delta was home to Cucapa or “people of the river.” They inhabited the Delta for nearly a thousand years and used the Delta floodplain to harvest Palmer’s saltgrass (a wild grain), and cultivate corn, beans, squash.

The Delta is major stopover along the Pacific Flyway

Endangered species in delta include desert pupfish, Yuma clapper rail, bobcat, vaquita porpoise, totoaba, yellow-footed gull, Heermann’s gull, elegant tern, reddish egret, peregrin falcon; brant, house finch, mockingbird, and great blue heron

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