As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned River Basins of the public lands and natural resources. This includes fostering the United States: wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoy­ ment of life through outdoor recreation. The Department assesses The Colorado our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Depart­ ment also has a major responsibility for American Indian reservation communities and for people who live in Island Territories under U.S. administration. U.S. Department of the Interior/Geological Survey i ..... River Basins of the United States: The Colorado This leaflet, one of a series on the river basins of the United States, contains infor­ mation on the Colorado River Basin, including a brief early history, a description of the physical characteristics, and other statistical data. At present, other river basins included in the series are The Columbia, The Delaware, The Hudson, The Potomac, and The Wabash. Early Exploration and Settlement Francisco de Ulloa, a Spanish soldier and explorer, was probably the first Euro­ pean to see the Colorado River. In 1776, Father Garces, a Spanish missionary, Major Tributaries Length named it the "Rio Colorado." Congress The Gunnison, White, Yampa, San Juan, The Colorado River is approximately applied the name "Colorado" to the entire Delores, Green, Little Colorado, Gila, and 1,440 miles long from its headwaters to its river in 1921. A prehistoric race called the Virgin Rivers are major tributaries of the mouth in the Gulf of California. It ranks 6th Hohokam lived and vanished in the Colorado. among 135 U.S. rivers that are more than Salt River Valley before the Hopi and the 100 miles long. Pueblo Indians inhabited the area. Father Eusebio Kino established the Jesuit Course missions in 1700 at San Xavier Del Bac From its headwaters, the river flows Width and in 1732 at Guevavi, both in Arizona. southwestward in a series of meanders The river is about 50 feet wide for the The first European settlement was estab­ across the high Colorado Plateau into south­ first 50 miles; at Grand Junction, Colo., it lished near present-day Tucson, in 1776. eastern Utah and through northwestern is 200 feet wide. Arizona. Slashing through a wilderness of Headwaters mountains, plateaus, and deserts, it is cliff- Depth bound nine-tenths of its way and travels The river rises in the Rocky Mountain 1,000 miles through deep canyons. The The river is about 30 feet deep in lower National Park in northcentral Colorado; it Grand Canyon is the largest, the deepest, reaches of the Grand Canyon; it is not becomes a perennial stream near Poudre and the most spectacular. The Colorado more than 10 feet in the upper reaches above Pass in Colorado. then bends south to form boundaries be­ the Grand Junction, Colo. tween Nevada and Arizona and between Mouth Arizona and California. It flows into the Rate of Flow The Colorado flows into the Gulf of Cali­ Gulf of California, after first forming the Near Lees Ferry, Ariz., the river's rate fornia. The approximate latitude at the boundary between the Mexican States of of flow is about 8 million gallons per minute mouth is 32° N. and the approximate longi­ Sonora and Baja California. (gpm); at the mouth it is about 2 million tude is 115° W. gpm. Colorado River Basin NEVADA Highest and Lowest Flow The highest recorded flow occurred at The river once was one of the most silt- Agricultural products which come from the Yuma, Ariz., in 1916; the lowest natural laden streams in the United States; now basin are: fruits, some cotton, general (unregulated) flow occurred at Lees Ferry reservoirs trap most of the sediment. farming, and grazing. Irrigated agriculture is in 1924. The average salinity is less than 50 parts practiced in every State in the basin. per million (ppm) in headwater areas but Dams, Reservoirs, and Canals often exceeds 1,000 ppm at the international The Flaming Gorge Dam, Utah; the Navajo boundary. Pollution from municipal and in­ Little industrial development exists in the Dam, N. Mex.; the Glen Canyon Dam and dustrial wastes is slight except in the vicinity of cities and towns. Most ground basin except light industry in the Phoenix, Lake Powell, Ariz., and Utah; the Blue Mesa Ariz., area. Dam, Colo.; the Hoover Dam and Lake water used for irrigation is not treated; that Mead and Davis Dam and Lake Mohave, used for municipal supply is chlorinated. Nev.; and the Parker Dam and Havasu Lake Minerals and Imperial Dam, Ariz., are all a part of Major Cities Minerals found in the basin are: uranium, the Colorado River. Phoenix, Ariz., is the largest city in the zinc, silver, molybdenum, copper, gold, lead, basin. Cities of lesser size are Duchesne coal, petroleum, and oil shale. Geologic Setting and Moab, Utah; Grand Junction, Colo.; The Colorado River Basin lies in three Boulder City and Las Vegas, Nev.; physiographic provinces: Southern and Tucson and Yuma, Ariz.; and Needles, The Hydrologic Data Network, maintained Rocky Mountain, Basin and Range, and Colo­ Calif. by the U.S. Geological Survey in cooperation rado Plateau. About 240,000 square miles with the individual States, is the chief source are arid to semiarid. The Colorado Plateau Municipal and (Industrial Water Use of basic data on water in this country. In is composed of horizontal, sedimentary Water use is limited because the basin cooperation with other agencies, the U.S. rock strata (sandstone, limestone, shale, is sparsely populated; it is one of the Geological Survey maintains 16,500 gaging conglomerate) which were uplifted least populated areas of its size in the stations that measure high and low flow of thousands of feet, faulted, and carved by Western Hemisphere. The principal uses are rivers, lakes, and streams; 27,500 observation erosion into broad plateaus, mesas, buttes, hydroelectric power generation and irriga­ wells that collect data on levels and pump- natural bridges, and deep canyons. tion which consumes nearly the entire flow. age of ground water; and 8,200 stations The Colorado Desert in the southwestern Large quantities of water are also diverted that measure water quality. part of the basin is extremely arid and to adjacent areas for municipal, indus­ hot. Most of it is below sea level. trial, and irrigation uses. About 2 million people in the basin use approxi­ mately 400 million gallons of publicly The basin area is 243,000 square miles supplied water each day and about 1/4 and includes parts of Wyoming, Colorado, of a million people in rural areas use ap­ Utah, New Mexico, Nevada, Arizona, and proximately 25 million gallons of ground California. water daily. This publication is one of a series of general interest publications prepared by the U.S. Geological Survey to provide Commercial! Water Use information about the earth sciences, natural resources, and Average Rainfall the environment. To obtain a catalog of additional titles in the An average of about 15 inches of rain falls The river and its system of dams provide series "General Interest Publications of the U.S. Geological facilities for flood control, irrigation, hydro­ Survey," write: annually over most of the basin, with a range Book and Open-File Reports Section of 5 inches in the Arizona deserts to more electric power; and boating, fishing, skiing, U.S. Geological Survey than 50 inches in the Colorado mountains. and swimming. Federal Center, Box 25425 Denver, CO 80225 U.S. GOVERNMENT PRINTING OFFICE 1987 190-755.