In the early 20th century, Central Arizona Project was a shared dream of Arizonans; a vision of water security and stability for future generations to enjoy their quality of life in a desert. Now that the 336-mile long water delivery system is a reality, the leadership of CAP is responsible for protecting and preserving what past generations were able to fund and build.

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. 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 US 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 farming 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.


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.

The entire system is operated from a control center at CAP Headquarters in north Phoenix. It is staffed 24/7 with operators who remotely monitor and control the system using a supervisory control and data acquisition (SCADA) computer system. Through a comprehensive system of cables and microwave units, the SCADA system links all components of the aqueduct and provides real-time data every 10 seconds, including water levels, flows and system alarms.

System Facts:

  • Reach 1, the first section of the canal that is wider and deeper than the rest of the system, acts as an internal reservoir system and holds 20% of all the water in the canal at any time.
  • The canal descends approximately 5” per mile.
  • The canal loses approximately 16,000 AF a year to evaporation, which is about 1% of the annual flow.
  • As water canal progresses west to east, the size of both the pumping plants and aqueduct diminishes.
  • Depending on flow, water takes 5-7 days to go from beginning to end of the aqueduct.
  • 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 about 250,000 homes.


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 our quality of life.

- Municipal & Industrial (MI&I)
CAP delivers “raw” water to cities and water utilities that then treat the water the deliver to customers.
- Agricultural
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
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 the 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 thanks to CAP and reliable, renewable Colorado Riverwater, the Arizona economy is thriving and residents enjoy a high quality of life. An economic impact study showed that over the last 30 years, Colorado Riverwater delivered by CAP contributed nearly $2 trillion to Arizona’s gross state product.

Ongoing funding

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 CAP Board of Directors based on projections of energy, operation, maintenance and replacements 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.

Leaders & Professionals

CAP is a municipal corporation and is governed by a 15-member popularly elected Board of Directors. Board members are elected from Maricopa (10), Pima (4) and Pinal (1) counties and regularly meet twice per month and adhere to all open meeting laws. Members serve staggered six-year terms.

CAP’s daily operations are managed by more than 450 professionals who are responsible for system maintenance and operations, repayment obligations, public outreach and engaging in water resource management programs for Arizona.