The Central Arizona Project (CAP) conveys water about 190 miles from the Colorado River at Lake Havasu on the Arizona-California border through a system of canals to Phoenix, Tucson and beyond. The CAP system includes a series of pumps and an integral storage reservoir at Lake Pleasant on the Agua Fria River. The system is capable of carrying up to 1.8 million acre-feet each year. Visit Related Links in the bottom left corner of this page for more information on the CAP.
The Salt River Project (SRP) conveys surface water from the Verde River and Salt River watersheds that lie to the north and east of Phoenix. The SRP system is composed of seven dams and lakes, of which, Roosevelt is the largest reservoir. SRP delivers water throughout the Valley, using a system of canals and 255 high-capacity wells. These canals stretch over 131 miles and use gravity to move the water. Phoenix water treatment plants receive about 20% of the water delivered each year by SRP to the metropolitan area (in 2013, SRP deliveries totaled just over 767,000 acre-feet).
Unlike the other sources of supplies - which can be used by anyone within the city limits - SRP supplies are available only to certain parts of the city, referred to as "on-project" lands.
The watersheds of the Salt, Verde and Colorado Rivers cover large areas of the Western U.S., including areas far from Phoenix. Because of this, wet or dry conditions in these watersheds can vary considerably from what we are experiencing in the Phoenix area in any given year.
Having diverse supplies helps the city in planning for future growth and coping with shortages. The CAP accounts for around 2/5 of the water supply. SRP supplies account for about one-half. The remainder of your water comes from wells or is recycled.