Colorado River Management Section

Overview - Central Arizona Project

The Central Arizona Project (CAP) brings approximately 1.5 million acre-feet of Colorado River water to farmers, Indian Tribes, and rapidly growing cities in central Arizona.  The 1968 Colorado River Basin Project Act authorized the CAP; construction began in 1973 and was substantially completed twenty years later.  The CAP has reduced dependence on dwindling groundwater resources by providing a stable, renewable supply of water.

The CAP provides a renewable water supply to preserve, but not expand, the agricultural economy of central Arizona.  The 1968 Act prohibits the use of CAP water for irrigation on non-Indian lands without a history of irrigation between 1958 and 1968.  The Act requires that CAP contracts contain provisions to control the expansion of groundwater use.  However, the focus on CAP as an agricultural water supply began to change in the early 1970’s as cities and towns in central Arizona began to grow.  The first State Water Plan published in the mid-1970’s noted that the growth of Arizona cities and industries could only be assured if groundwater pumping was offset by the use of CAP water. 

The pressures to reduce groundwater pumping and use CAP water supplies as an alternative supply led directly to enactment of the 1980 Groundwater Management Code with its policy to protect and stabilize the general economy and welfare of the state by managing water resources. At the same time some Indian communities began to assert their water right claims, requesting an increased share of CAP water.  The availability of future CAP water supplies allowed water rights settlements to be enacted for the Ak Chin, Gila River, Tohono O’Odham, Salt River-Pima Maricopa, Fort McDowell, and San Carlos Apache Indian Communities.  A listing of CAP contracts and subcontracts can be found at www.cap-az.com.

 

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