In the early 20th century, Arizona’s leaders knew the state’s future depended on a water supply that was secure, stable and renewable. They pursued that vision; the result was Central Arizona Project (CAP), a 336-mile system that brings Colorado River water to central and southern Arizona, delivers the state’s single largest renewable water supply and serves 80% of the state’s population.

CAP’s Vision

CAP will be a collaborative, innovative leader in the management and the delivery of water to central Arizona. It will enhance the state’s economy and quality of life and ensure sustainable growth for current and future populations of Arizonans.

Arizona knew the importance of water

In the early 1900s, the seven states that share the Colorado River Basin – Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming – negotiated for shares of its water. Ultimately, the states were divided into the Upper Basin and Lower Basin and each basin was allocated 7.5 million acre-feet (MAF) of water. Arizona, Nevada and California comprise the Lower Basin and receive 2.8 MAF, 300,000 AF and 4.4 MAF respectively. The 1944 U.S.-Mexico Water Treaty provides 1.5 MAF of Colorado River water to be delivered to Mexico annually. One acre-foot equates to a yearly supply for three Arizona families.

In 1968, President Lyndon B. Johnson signed the Colorado River Basin Project Act, which authorized construction of CAP by the U.S. Department of the Interior’s Bureau of Reclamation. The system would provide a way for 1.5 MAF of Arizona’s allotment to be delivered to the most populous areas of the state and reduce the use of groundwater for agriculture and other activities. In 1971, the Central Arizona Water Conservation District (CAWCD) was created to provide Arizona a means to repay the federal government for the reimbursable costs of construction and to manage and operate the physical system. CAWCD, commonly referred to as CAP, continues today to strive toward the CAP vision.


CAP is governed by a 15-member popularly elected Board of Directors. CAWCD Board members are elected from Maricopa (10), Pima (4) and Pinal (1) counties, serve staggered six-year terms and are not compensated for their time. The Board regularly meets twice per month and adheres to all open meeting laws.

CAP’s daily operations are managed by nearly 500 professionals who are responsible for system maintenance and operations, repayment obligations, public outreach and engaging in water resource management programs for Arizona.


Construction of the CAP system began in Lake Havasu in 1973 and was completed 20 years later south of Tucson at a cost of more than $4 billion. The result is an engineering marvel that pumps water uphill. Water enters the system at Mark Wilmer Pumping Plant where six 66,000 horsepower pumps lift water more than 800 vertical feet into the seven-mile long Buckskin Mountain Tunnel. It then flows into the open canal where it continues its journey across the state.

A complex system

The canal system stretches 336 miles, lifts the water more than 2,900 feet in elevation over the course of the system and includes 14 pumping plants, one hydroelectric pump/generating plant at New Waddell Dam, Lake Pleasant storage reservoir, 39 radial gate structures to control the flow of water and more than 50 turnouts to deliver water.

System Facts:

  • Reach 1 is the first section of the canal and is wider and deeper than the rest of the system. It acts as an internal reservoir system and holds 20% of all the water in the canal at any time.
  • CAP is the largest single power user in the state, using up to 2.8 million megawatt hours per year, roughly the amount used by 250,000 homes.
  • The canal loses approximately 16,000 acre-feet a year to evaporation, which is about 1% of the annual flow.
  • The canal descends approximately 5” per mile.
  • Depending on flow, water takes 5-7 days to go from beginning to end of the aqueduct.
  • As water in the canal progresses west to east, the size of both the pumping plants and aqueduct diminishes.


CAP has more than 80 long-term water users that fall into three user groups. They use CAP’s Colorado River water to run businesses, water crops and maintain households, all of which is critical to the quality of life in Arizona.

Municipal & Industrial
- CAP delivers “raw” water to cities and water utilities that then treat the water they deliver to customers.
- CAP’s agricultural water users are primarily large irrigation districts that deliver water to farmers. The majority of CAP water is used for agriculture.
Native American Tribes
- Through a contract with the U.S. Department of the Interior, CAP delivers water to Native American Tribes in central and southern Arizona. The tribes may use their water in their community or lease it to others.


CAP establishes and maintains collaborative relationships with water users, tribal nations and regional, state and federal agencies. These relationships help CAP respond to emerging issues affecting CAP and its stakeholders and advance the understanding of policy issues important to CAP operations and the entire state.


Few natural resources are as precious as water, and by CAP providing reliable, renewable Colorado River water, the Arizona economy is stronger and residents can enjoy a higher quality of life.

Repayment and Revenue

CAP generates revenue in a variety of ways to fund its operation and maintenance and to fulfill repayment obligations to the federal government and bondholders. Revenue is generated by the sale of water and power; capital and facility-use fees paid by water users; property taxes paid by non-Indian reservation residents of Maricopa, Pima and Pinal counties; and investments.

The price of water is determined annually by the CAWCD Board of Directors based on projections of energy, operation, maintenance and replacement costs. As a public entity, CAP does not make a profit and has a responsibility to provide a reliable water supply at
a reasonable price.