ADEQ: Arizona Department of Environmental Quality, Arizona's Official Web Site
Our mission is to protect and enhance public health and the environment
Water Quality Division: Groundwater Public Landing Page


ADEQ uses water quality permits to safeguard Arizona's waters that are affected by pollutants that come from an identifiable source. These permits protect groundwater quality by controlling discharges from domestic wastewater treatment plants, mining operations, industrial facilities, on-site sewage disposal systems, direct reuse of reclaimed water as well as discharges to drywells.

A facility must obtain an Aquifer Protection Permit (APP) if the facility discharges a pollutant either directly to an aquifer, to the land surface or the vadose zone (the area between an aquifer and the land surface) in such a manner that there is a reasonable probability that the pollutant will reach an aquifer. ADEQ issues both general and individual APPs and publishes a list of applications that have been received for individual APPs. The list may be obtained by subscribing to the Water Quality Individual Permits in Process e-newsletter.

When ADEQ determines that an individual APP will be issued, a notice is published in the newspaper and ADEQ requests public comments on the permit. Public comments are considered part of the permit decision and ADEQ provides responses to the comments. If there is significant interest, a public hearing may also be held. Information on Individual APPs currently in public notice can be obtained by typing “Aquifer Protection Permit” in the “Search event” box in the Events and Notices Calendar.


Drywell Registration

Drywells are wells that are designed and constructed specifically for the disposal of storm water. Typically drywells are covered by a grate at the ground surface and have a settling chamber to collect sediment and an injection pipe to allow storm water to percolate into underground soil and eventually to groundwater. Because of this, it is important to keep contaminants and wastes from entering the drywell.

All drywells are required to be registered with ADEQ which includes a fee and information on the location and owner of the drywell. If the drywell can receive storm water from areas where motor vehicles are fueled or where hazardous substances are present, the drywell owner will also need to obtain an APP.


The Arizona Pesticide Groundwater Quality Protection Program was established to prevent or eliminate the pollution of state groundwater aquifers from agricultural pesticides. The program is responsible for evaluating groundwater data submitted in support of new pesticide product registration, and identifying which active ingredients and products have the potential of polluting groundwater. The program generates the Groundwater Protection List (GWPL), which enforces data gap violations and conducts regular groundwater monitoring. An annual report on pesticide use is presented to the state legislature.

Pursuant to the Environmental Quality Act of 1986, ADEQ requires applicants intending to register new agricultural-use pesticides with the Arizona Department of Agriculture to submit groundwater protection data for review and approval. After completing a substantive technical review, ADEQ determines if the product's active ingredient poses a threat to groundwater quality. For more information click here.

Groundwater Monitoring and Data Collection

The ADEQ groundwater monitoring program seeks to characterize groundwater quality in each of the 51 groundwater basins that have been designated in Arizona by state agencies. Comprehensive groundwater sampling is conducted in a basin following the approval of a sample plan.

Data collected by this program are incorporated into ADEQ's Groundwater Database as well as provided to the well owner from which the groundwater sample was collected. A comprehensive Open File Report and a condensed four-page Fact Sheet are published for each basin. Index wells are selected in these basins which will be resampled in the future to determine groundwater quality change over time.

These ADEQ basin studies are an important resource, especially with many people moving to locations in Arizona not served by public water systems. Residents utilizing groundwater supplied by public water supply systems have the assurance that this resource is regularly tested and meets water quality standards set by the Safe Drinking Water Act (SDWA). However, no such regulations exist for residents served by private wells. While collecting and analyzing groundwater samples from all private wells would be prohibitively expensive, ambient groundwater quality studies that use scientific and statistical principles to estimate groundwater quality conditions provide an affordable alternative. As such, this program provides important groundwater quality information to the public, including the expected groundwater quality within a basin, areas where specific groundwater quality problems can be expected to occur, and whether there has been any change over time in the groundwater quality of the basin.

Groundwater Studies

The ADEQ Ambient Monitoring Program has completed reports covering 20 groundwater basins within Arizona. These reports are available in two formats: a comprehensive Open File Report (OFR) and a compact four-page fact sheet (FS). The OFR is designed for audiences seeking an indepth hydrologic analysis of the basin. In contrast, the FS is designed for a more general audience seeking a brief overview of the groundwater quality of the basin.

The data for all samples collected for these studies, besides being available in the individual OFRs are also available through the ADEQ Groundwater Database. This database includes all samples collected by the ADEQ Ambient Groundwater Monitoring Program as well as other monitoring programs within the agency.