Water is the lifeblood of the arid West. Without water we don’t have farms or ranches—or towns and cities. There have been many battles over land and water, and especially water, because land without water is worthless. Western water law and water rights came into existence to try to prevent and resolve conflicts between water users.
The Colorado River is one of the largest and longest rivers in the Southwest. This 1,450-mile-long river and its tributaries are part of a large, arid watershed in seven states and northern Mexico. Starting in the mountains of Colorado, the river flows southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona/Nevada border, where it turns south and enters Mexico.
Along with its dramatic canyons and 11 national parks, the Colorado River and its tributaries are a vital source of water for more than 40 million people. It is controlled by an extensive system of dams, reservoirs, and aqueducts, which divert water for agricultural irrigation and domestic water supplies. Its large flow is also used for generating hydroelectric power.
Settlement in this arid region was slower than in “greener” areas of Oregon and California. The first major settlements began in the 1850s by Mormons who came to what is now Utah and Arizona, and miners prospecting for gold. Gold strikes from the mid-19th to early-20th centuries attracted settlers to the upper Colorado River Basin.
As settlements grew, the river and its tributaries were harnessed to provide the necessary water. Today more than 29 major dams and hundreds of miles of canals supply water to cities and provide irrigation for more than 4 million acres.
For instance, the Central Arizona Project (CAP) was created by the Colorado River Basin Project Act of 1968. It consists of a 336-mile diversion canal in Arizona that diverts water from the Colorado River from the south portion of Lake Havasu into central and southern Arizona. This project was created to provide water to nearly one million acres of irrigated agricultural land areas in Maricopa, Pinal, and Pima counties, and municipal water for several Arizona communities, including Phoenix and Tucson.
Colorado River Compact
During early settlement and development there were problems with flooding wiping out some of the early dams, flooding farms and towns. In 1922, states in the Colorado River Basin signed the Colorado River Compact, creating an agreement for governing allocation of water rights to each state.
The compact divided the river basin into the Upper Division (Colorado, New Mexico, Utah, and Wyoming) and the Lower Division (Nevada, Arizona, and California). The compact requires the Upper Basin states not to deplete annual flow of the river below 7.5 million-acre feet during any 10-year period. Based on rainfall patterns during the years before the treaty signing in 1922, the amount specified in the compact was assumed to allow a roughly equal division of water between the two regions.
States within each basin were required to divide their 7.5 million-acre foot-per-year share allotment among themselves. The compact enabled widespread irrigation of the Southwest, as well as subsequent development of state and federal water projects under the Bureau of Reclamation. These projects included the Hoover Dam and Lake Powell.
Then a U.S.-Mexico treaty in 1944 allocated 1.5 million-acre feet of Colorado River water to Mexico each year. Arizona had previously refused to ratify the Colorado River Compact in 1922 because it feared California would take too much of the Lower Basin allotment. In 1944, a compromise was reached in which Arizona would have allocation of 2.8 million-acre feet, but only if California’s 4.4-million-acre-foot allocation was prioritized during drought years. These and nine other decisions, compacts, federal acts, and agreements were made between 1922 and 1973.
Drought difficulties
In recent decades, decreased precipitation led to dwindling reservoir levels, particularly at Lake Powell, which was created by the Glen Canyon Dam in 1963. When the Colorado River Compact was drafted in the 1920s, it was based on 30 years of streamflow records that suggested an average annual flow of 17.5 million-acre feet past Lee’s Ferry. More recent studies of tree rings reveal that those three decades were probably the wettest in the past 500-1,200 years and that the natural long-term annual flow past Lee’s Ferry is probably closer to 13.5 million-acre feet.
The most severe drought on record began 20 years ago; the river basin produced normal or above-average runoff in only four of the years between 2000 and 2012. Major reservoirs dropped to historic lows. Lake Powell dropped to just one-third of its capacity in early 2005, the lowest level on record since 1969.
In late 2010, Lake Mead dropped to just 8 feet above the first “drought trigger” elevation, a level at which Arizona and Nevada would have to begin rationing water as ordered by the Colorado River Compact. Despite above-average runoff in 2011 that raised the reservoir more than 30 feet, severe drought conditions returned in 2012 and 2013. Reservoir levels were low enough in early 2014 that the Bureau of Reclamation cut the releases from Lake Powell by 750,000-acre feet.
This resulted in Lake Mead dropping to its lowest recorded level since 1937, when it was first filled. Rapid development and economic growth further complicate the issue of a secure water supply, particularly with California’s senior water rights over those of Nevada and Arizona: In case of reduction in supply, Nevada and Arizona would have to endure severe cuts before any reduction in the California allocation, which is larger than the other two combined. Stringent water conservation measures have been implemented, but the threat of severe shortfalls in the Colorado River Basin continues to increase each year.
Ever since the development of the Colorado River Compact, California has been using any surplus water left over from other states. With increasing population growth in the Southwest there’s been concern that this surplus soon will not exist for California’s use. In 2001, Secretary of Interior Bruce Babbitt signed an interim agreement to determine how water surplus from the Colorado River would be allocated between the states, creating a 15-year period to allow California time to put conservation methods in place to reduce their water usage and dependence on Colorado River water.
In December 2007, a set of interim guidelines on how to allocate Colorado River water in the event of shortages was signed by the secretary of the interior. These guidelines extend through 2026, intending to provide the states time and opportunity to gain management experience for Lakes Powell and Mead during low reservoir conditions. The agreement specifies three levels of shortage, depending on the level of Lake Mead, and how the water allocations would be reduced in those situations.
As dry conditions continue, further actions have been taken, including creation of drought contingency plans in each of the affected states. — Heather Smith Thomas, WLJ correspondent
