How Lake Mead became a water source for Las Vegas, Nevada, California, and Arizona

LAS VEGAS (KLAS) — When Americans began populating what would become Nevada, California, and Arizona the need for clean running water was there, but it wasn’t until the turn of the 20th century that people were able to convince the government to invest millions to figure out how to control and distribute Colorado River water safely and consistently.

For years people tried to control the Colorado River for irrigation, failing over and over. It wasn’t until 1906 that a historic flood in the Imperial Valley changed the nation’s mind on spending money to harness the power of the river.

The Colorado River is managed and operated by the United States Bureau of Reclamation (USBR) – an agency formed under several federal laws, compacts, court decisions and decrees, contracts, and regulatory guidelines known as the “Law of the River.”

The 1906 flood was the first in a series of events — natural and man-made — that changed the southwest forever. As the region looks perilously into a future where Lake Mead could lose another 20 to 30 feet in 2023 alone, it’s important to understand how the situation became what it is. Below are descriptions of a series of events and legal documents that led to the taming of the Colorado River.

  • 1906
    • Colorado River flood in Imperial Valley. The urgent necessity of river flood control is revealed.
  • 1918
    • Congress adopted the Kincaid Act, authorizing a study of the lower Colorado River by the US Reclamation Service.
  • 1922
    • Department of the Interior submitted to Congress a report and recommendation for flood control and development of the lower Colorado River. The report recommended the construction of a dam at Boulder Canyon.
  • 1922
    • Representatives from seven Colorado River Basin States, following a series of public hearings, presided over by Herbert Hoover, then Secretary of Commerce, signed Colorado River Compact. This Compact provided for the division of waters between Upper and Lower Basin States. Upper Basin includes Colorado, New Mexico, Utah, and Wyoming. Lower Basin, Arizona, California, and Nevada.
  • 1922
    • Bills for the development of the Lower Colorado River based upon the recommendations of the Interior Department were introduced in Congress by Senator Hiram W. Johnson and Representative Phil D. Swing.
  • 1928
    • Congress adopted the Swing-Johnson Bill. Signed by President Coolidge on Dec. 21
  • 1930
    • July 8th. Congress authorized the first appropriation ($10,000,000) to start work on the Boulder Canyon project. March 10th. Hoover Dam construction contract awarded to Six Companies, Inc., by US Reclamation Service. Work on Dam immediately launched.
  • 1931
    • May 17th. US Supreme Court dismissed Arizona lawsuit seeking to prevent the construction of Boulder Dam.

It’s Happened Before: Lake Mead’s wild water level ride

The following is a synopsis of the most significant documents written by the USBR.

The Colorado River Compact of 1922

To dive deeper into the language of the laws controlling water from the Colorado River, a good starting point is the Colorado River Compact of 1922.

This Compact was negotiated by the seven Colorado River Basin states and the federal government in 1922. It defined the relationship between the upper basin states, where most of the river’s water supply originated, and the lower basin states, where most of the water demands were developing. At the time, the upper basin states were concerned that plans for Hoover Dam and other water development projects in the lower basin would, under the Western water law doctrine of prior appropriation, deprive them of their ability to use the river’s flows in the future.

The states could not agree on how the waters of the Colorado River Basin should be allocated among them, so the Secretary of Commerce Herbert Hoover suggested the basin be divided into an upper and lower half, with each basin having the right to develop and use 7.5 million acre-feet (maf) of river water annually. This approach reserved water for future upper basin development and allowed planning and development in the lower basin to proceed.

U.S. Bureau of Reclamations

The Boulder Canyon Project Act of 1928

This act: (1) ratified the 1922 Compact; (2) authorized the construction of Hoover Dam and related irrigation facilities in the lower Basin; (3) proportionate the lower basin’s 7.5 maf among the states of Arizona (2.8 maf), California (4.4 maf) and Nevada (0.3 maf); and (4) authorized and directed the Secretary of the Interior to function as the sole contracting authority for Colorado River water use in the lower basin.

U.S. Bureau of Reclamations

Transcribed from the back of the photo, “Prayer of thanks for signing of Boulder Dam Bill” March 3, 1929 (UNLV Digital Collections)

California Seven Party Agreement of 1931

This agreement helped settle the long-standing conflict between California agricultural and municipal interests over Colorado River water priorities. The seven principal claimants – Palo Verde Irrigation District, Yuma Project, Imperial Irrigation District, Coachella Valley Irrigation District, Metropolitan Water District, and the City and County of San Diego – reached a consensus in the amounts of water to be allocated on an annual basis to each entity. Although the agreement did not resolve all priority issues, these regulations were also incorporated into the major California water delivery contracts.

U.S. Bureau of Reclamations

President Franklin D. Roosevelt gave his dedication speech to a crowd at the Boulder Dam dedication ceremony – renamed Hoover Dam in 1947. Sept. 30, 1935 (Image: UNLV Digital Collections)

The Mexican Water Treaty of 1944

This agreement committed 1.5 maf of the river’s annual flow to Mexico.

Upper Colorado River Basin Compact of 1948

(This act) created the Upper Colorado River Commission and apportioned the Upper Basin’s 7.5 maf among Colorado (51.75%), New Mexico (11.25%), Utah (23%), and Wyoming (14%); the portion of Arizona that lay within the Upper Colorado Basin was also proportioned 50,000 acre-feet annually.

U.S. Bureau of Reclamations

Colorado River Storage Project Act of 1956

(This act) provided a comprehensive Upper Basin-wide water resource development plan and authorized the construction of Glen Canyon, Flaming Gorge, Navajo, and Curecanti dams for river regulation and power production, as well as several projects for irrigation and other uses.

U.S. Bureau of Reclamations

The Arizona v. California US Supreme Court Decision of 1964

In 1963, the Supreme Court issued a decision to settle a 25-year-old dispute between Arizona and California. The dispute stemmed from Arizona’s desire to build the Central Arizona Project so it could use its full Colorado River apportionment. California objected and argued that Arizona’s use of water from the Gila River, a Colorado River tributary, constituted the use of its Colorado River apportionment and that it had developed a historical use of some of Arizona’s apportionment, which, under the doctrine of prior appropriation, precluded Arizona from developing the project.

The Supreme Court rejected California’s arguments, ruling that lower basin states have a right to appropriate and use tributary flows before the tributary co-mingles with the Colorado River and that the doctrine of prior appropriation did not apply to apportionments in the lower basin.

In 1964, the Court issued its decree. This decree enjoined the Secretary of the Interior from delivering water outside the framework of apportionments defined by the law and mandated the preparation of annual reports documenting the uses of water in the three lower basin states.

In 1979, the Supreme Court issued a Supplemental Decree which addressed present perfected rights referred to in the Colorado River Compact and in the Boulder Canyon Project Act. These rights are entitlements essentially established under state law and have priority over later contract entitlements.

On March 27, 2006, the Supreme Court issued a Consolidated Decree to provide a single reference to the provisions of the original 1964 decrees and several subsequent decrees (1966, 1979, 1984, and 2000) that stemmed from the original ruling. This decree also reflects the settlements of the federal reserved water rights claim for the Fort Yuma Indian Reservation.

U.S. Bureau of Reclamations

The Colorado River Basin Project Act of 1968

This Act authorized the construction of a number of water development projects in both the upper and lower basins, including the Central Arizona Project (CAP). It also made the priority of the CAP water supply subordinate to California’s apportionment in times of shortage, and directed the Secretary to prepare, in consultation with the Colorado River Basin states, long-range operating criteria for the Colorado River reservoir system.

U.S. Bureau of Reclamations

The Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs of 1970

(This document) provided for the coordinated operation of reservoirs in the upper and lower basins and set conditions for water releases from Lake Powell and Lake Mead. On March 21, 2005, following a public review process, including consultation with the seven Colorado River Basin States and other interested parties and stakeholders, the Secretary of the Interior made a number of limited modifications to the text of the 1970 operating criteria. The associated Federal Register notice annotates the modifications and describes the public process and comments that resulted in the changes.

U.S. Bureau of Reclamations

Minute 242 of the US-Mexico International Boundary and Water Commission of 1973

(This) required the US to take action to reduce the salinity of water being delivered to Mexico at Morelos Dam.

U.S. Bureau of Reclamations

The Colorado River Basin Salinity Control Act of 1974

(This act) authorized desalting and salinity control projects, including the Yuma Desalting Plant, to improve Colorado River quality.

U.S. Bureau of Reclamations

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