Local Water Sources

Phoenix and its surrounding cities—Chandler, Mesa, Tempe, Glendale, Scottsdale and Peoria—have diverse sources of fresh water. These include several major surface water streams (including the Salt, Gila, Verde, and Agua Fria Rivers), and more recently, the CAP canal. Dams located on these rivers, which flow from the mountains north and east of Phoenix, form reservoirs that provide a steady supply of water. Surface water and CAP water provide about 57% of the Phoenix area water supply. However, if drought persists and the pattern of snow fall and precipitation changes, it is unlikely that these surface water resources will increase in the near future.

Phoenix and its surrounding communities also supplement their water needs by pumping from several large aquifers. However, large portions of the ground water along the Salt and Gila Rivers are high in salinity (> 3000 mg/L TDS). Consequently, the City of Phoenix, which delivers potable water to 1.3 million people, utilized ground water for only 8% of its water supply in 2002. CAP water and recycled wastewater, or effluent, is used to recharge local ground water aquifers for future use.

Tucson has no surface water (streams, lakes, or rivers) supplies. These sources were quickly depleted during the first part of the twentieth century, mostly by local ground water pumping which lowered the water table and depleted river base flow. Although ground water levels have dropped in the center of the Tucson basin by more than 200 feet over the past fifty years, growth has been sustained by the continued use of ground water and CAP water. Since 1996, CAP water that is not used directly is discharged into ground water recharge basins and stored aquifers.  This has slowed the lowering of ground water elevation in the Tucson Aquifer.

Yuma obtains drinking water for its 100,000 residents primarily from the Colorado River and holds the oldest water rights on the river. Ground water is used locally for irrigation, blended with surface water for municipal supply, and used occasionally for emergency supply. Most of the water diverted from the Colorado River in Yuma is used for agriculture, while drainage wells are used so that the land doesn’t become water-logged from irrigation application.

Flagstaff has diverse but limited sources of water. The primary sources are Lake Mary (located to the southwest), and wells and springs (located to the north). However, both sources are fed by snowmelt, which can vary greatly from year-to-year. Ground water is also available but it is deep (1,000–2,000 feet below land surface) and, consequently, expensive to pump. 

The Prescott area and Yavapai County have the unique distinction of having more exempt, private domestic water supply wells than any other area in Arizona.  Currently, over 30% of all new wells drilled in Arizona are in Yavapai County, with the greatest concentration of these wells in the Prescott area. The City of Prescott obtains most of its water supply from ground water wells. Arizona law allows the transportation of ground water pumped from the Big Chino ground water sub-basin, located north of the City, into the Prescott AMA. The City of Prescott has purchased the Big Chino Ranch for the purpose of supplementing water supply. While the law allows pumping of up to 14,000 acre-feet of ground water a year, the actual permitted volume has not yet been determined.

Click here to access AZ Cooperative Extension's "Well Owners’ Guide to Ground Water Resources in Yavapai County"