Water Information Program: Colorado water history, law and infrastructure

Smith Ditch Washington Park, Denver
Smith Ditch Washington Park, Denver

From the Glenwood Springs Post Independent (Denise Rue-Pastin):

The history of the Colorado River mirrors the history of the American West. Competing water uses from the Colorado River system have defined Colorado history for more than 100 years. As people around the state discuss how to manage water resources into the future, it is instructive to look back at the formation of the practices that govern allocation of the state’s water. This overview is provided by the Durango-based Water Information Program, on the Web at http://www.waterinfo.org.


The legal right to divert and use water in Colorado has been deliberated and defined from before the time of statehood in 1876. As stated in the state Constitution, “Prior appropriation shall give the better right as between those using the water for the same purpose …” This is the basis for the first in use, first in right doctrine of water appropriation, which is one of the legal foundations upon which water is managed in Colorado.

The Colorado Water Conservation Board (CWCB) oversees water issues in the State of Colorado, and the Colorado Division of Water Resources administers water allocation in accordance with court decrees and state legislation. The State Engineer’s office has maintained meticulous records on water usage, diversions and streamflows for many years. Two-hundred professional staff members work together to administer Colorado’s water according to the doctrine of prior appropriation, state law, water court decrees and interstate compacts.


Colorado has the enviable position in the West as being a water-producing state, with numerous mountain ranges capturing the winter snows that feed our streams and rivers. The seasonal nature of streamflows is not consistent with the demand by Colorado citizens for domestic, agriculture and industry uses. Nearly two-thirds of the annual water flow occurs during the late spring/early summer runoff. During the winter months of December, January and February only 3 percent of annual flows occur.

Colorado reservoirs store the spring runoff from mountain snowpack for use in the late summer and low-flow winter months. This “reserved” water is stored for use throughout the year by downstream users. In addition, water storage units along the Colorado River system provide flood control, recreational sports, excellent fishing and hydro-electric power.


Water leaving Colorado on an annual basis exceeds 10 million acre feet. The Colorado River west of Grand Junction provides nearly 5 million acre feet of that amount for downstream users. The Colorado River Compact is the ruling document that was established after long negotiations between the seven states along the Colorado River in 1922.

After the U.S. Supreme Court ruled that the waters of the Colorado River would be governed according to the Doctrine of Prior Appropriation, the Upper Basin states (Utah, New Mexico, Wyoming and Colorado) became concerned that the Lower Basin states (California, Arizona and Nevada) would be at an unfair advantage if this doctrine was applied across state lines due to the Lower Basin’s more rapid development of water resources.

As a result of complex negotiations between the states in a forum called the Colorado River Commission, the elements of the famous Colorado River Compact were forged between the seven states along the Colorado River system. Under this compact, the Upper Basin states are required to allow an average of 7.5 million acre-feet per year flow downstream from Lake Powell to the Lower Basin States — theoretically splitting the rights to the river’s total flow in half, although in recent decades the total yield of the river has typically been considerably lower than the amount assumed by compact.

Although the Colorado River Compact formed the basis for the “Law of the River,” much debate and deliberation was to follow the historic 1922 treaty. For example, Wyoming challenged Colorado’s right to divert headwaters streamflow from the west to east slope of Colorado.

In 1944, a treaty was signed with Mexico providing our neighbor to the south with 1.5 million acre feet annually from the Colorado River system. In 1948, the Upper Basin States agreed to a percentage appropriation of their share of the waters of the Colorado River System. Colorado’s share was set at 51.75 percent.


In 1902, the U.S. Bureau of Reclamation (USBR) was created. Ever since, the USBR has been coordinating the planning, construction and implementation of numerous water diversion and storage projects in the western United States. Irrigation projects throughout the West are based on contracts between the water users and the USBR. Hydro-electric power revenues are used to offset some of the costs of irrigation projects and repayment contracts. The USBR manages existing water reservoirs in the Colorado River System that were constructed with federal financing.

Present and future generations will continue to wrestle with the issues of how to allocate the Colorado River between competing demands. Indian water rights, endangered species, water quality, interstate conflicts and environmental legislation are among the factors that must be considered. Over the past 100 years, the history of water in Colorado has helped shape the “Law of the River” throughout the Basin and our state. How we manage, conserve, store and distribute water will remain one of Colorado’s most pressing policy challenges, with implications beyond our borders.

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