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Water Management


Phoenix Active Management Area Overview


Active Management Areas

Map of AMAs in Arizona In 1980, in response to legal challenges, funding threats to the Central Arizona Project and the problems associated with severe groundwater overdraft, the Arizona Legislature passed the landmark Groundwater Management Act. The Legislature embodied its intent in the Declaration of Policy: is necessary to conserve, protect and allocate the use of groundwater resources of the state and to provide a framework for the comprehensive management and regulation of the withdrawal, transportation, use, conservation and conveyance of rights to use the groundwater in this state.” §45-401(B).


The Act created the Arizona Department of Water Resources, ensured completion of the CAP, and established Active Management Areas with long-term management goals.  Within AMAs, rights were established, wells are regulated, and the municipal, industrial and agricultural sectors are subject to mandatory conservation programs that are established in Management Plans adopted every ten years. Since 1980, the basic framework of the Act has been built upon to include provisions for recharge and recovery, assured water supply, water banking and groundwater replenishment.


An overview of the Groundwater Management Code PDF



Phoenix AMA Description

The Phoenix AMA is located in central Arizona and is one of the five Active Management Areas (AMA) mandated by the Groundwater Code. The Phoenix AMA covers 5,646 square miles and consists of seven groundwater basins:

  • East Salt River Sub basin
  • West Salt River Sub basin
  • Hassayampa Sub basin
  • Fountain Hills Sub basin
  • Rainbow Valley Sub basin
  • Lake Pleasant Sub basin
  • Carefree Sub basin


The AMA is in the basin and range physiographic province. Elevations range from less than 800 feet above mean sea level (msl) at Gillespie Dam to over 6,000 feet above msl in the Superstition Mountains in the eastern portion of the AMA.


Water Sources


The AMA is characterized by a diverse mix of water uses, with a heavy and increasing emphasis on municipal and industrial uses.

Water of PhxAMA

Multiple sources of water (CAP, Salt and Verde surface water, effluent and groundwater) are available and are being used to varying degrees.


Approximately 2.3 million acre feet of water is used annually on average in the Phoenix AMA, with 1.6 million acre feet of renewable water (CAP, Salt and Verde surface water, and effluent) used and 705,000 acre feet of groundwater used.


The Phoenix AMA is drained by the Gila River and four principal tributaries: the Salt, the Verde, the Agua Fria, and the Hassayampa Rivers.


Other tributaries include Queen Creek, New River, Skunk Creek, Cave Creek, Waterman Wash, and Centennial Wash. Regulatory water storage reservoirs have been constructed on the Salt, Verde, and Gila Rivers and for the Agua Fria River, allowing for a relatively high proportion of surface water use in some areas of the Phoenix AMA.


Located primarily in subtropical desert, the climate of the Phoenix AMA is semi-arid, receiving an average of seven inches of annual precipitation.



Irrigation Non-Expansion Area (INA)

The 1980 Groundwater Management Act established two Irrigation Non-Expansion Areas (INAs) - the Joseph City INA and the Douglas INA. Since the law was passed, the Harquahala area has also been designated an INA. When an area is designated as an INA, a restriction is placed on increasing the number of irrigated acres in the area.

An INA is a geographical area that has been designated as having insufficient groundwater to provide a reasonably safe supply for the irrigation of the cultivated lands at the current rate of withdrawal. Within INAs, new agricultural use of land occurring on land that was not irrigated in the five years preceding the designation of the INA is prohibited with a few exceptions for substitution or transfer of acres under specified circumstances.

Joseph City INA

established by the 1980 Groundwater Management Act

land that was legally irrigated at any time between January 1, 1975 and January 1,1980 may continue to be irrigated

Harquahala INA

designated by ADWR in 1982

the period establishing the right to irrigate is January 6, 1976 to January 6, 1981.




Phoenix AMA Navigation Links