Water Quality Division: Standards

What are aquifer water quality standards?

The aquifer water quality standards (A.A.C. R18-11 Article 4) establish the water quality goals for groundwater in Arizona which is to maintain and protect groundwater quality for drinking water use. ADEQ has established aquifer water quality standards, based on the primary maximum contaminant levels (MCLs) under the Safe Drinking Water Act, for all aquifers in the state “to preserve and protect the quality of those waters for all present and reasonably foreseeable future uses” (A.R.S. 49-221). All aquifers in Arizona are classified for drinking water protected use (A.R.S. § 49-224(B)) unless otherwise designated by the Director after review and consultation described in A.R.S. §49-224(C). To date, no aquifers in Arizona have been reclassified to a non-drinking water protected use. The process for establishing aquifer boundaries and reclassification is found in A.A.C. R18-11 Article 5.

How are AWQS used?

Aquifer water quality standards provide the regulatory basis for permit conditions under the Aquifer Protection Permit (APP) program. The APP program regulates the discharge of pollutants to aquifers, thereby preventing or reducing groundwater contamination. In the APP program, a “discharge” means the addition of a pollutant from a facility directly to an aquifer or to the land surface or the vadose zone in such a manner that there is a reasonable probability that the pollutant will reach an aquifer (A.R.S. 49-201). The APP program does not regulate naturally occurring pollutants in aquifers, for example, in some locations, arsenic and uranium.

Aquifer water quality standards also may be used to establish clean-up levels for remedial actions initiated under the Water Quality Assurance Revolving Fund (WQARF), federal Superfund and Underground Storage Tank (UST) programs. WQARF and UST regulations authorize ADEQ to approve remedial or corrective actions that may result in water quality exceeding water quality standards after completion of the actions. This authority recognizes that, in some cases, it may not be feasible to clean up contaminated groundwater to levels that meet aquifer water quality standards but approval of such remedial actions does not affect the classification of an aquifer pursuant to A.R.S. § 49-224.

What are reclaimed water standards?

Direct reuse of reclaimed water allows the use of treated effluent for certain beneficial uses, conserving potable water sources for human consumption and domestic uses. To protect public health and the environment, the reclaimed water quality standards (A.A.C. R18-11 Article 3) establish five classes of reclaimed water containing a combination of minimum treatment requirements and a limited set of numeric water quality criteria.

  • Class A reclaimed water is required for reuse applications where access to the reclaimed water by the general public in uncontrolled.
  • For uses where access to the reclaimed water by the general public is controlled, Class B and Class C are acceptable.
  • There are two "+" categories of reclaimed water, Class A+ and Class B+. Both categories require treatment to produce reclaimed water with a total nitrogen concentration of less than 10 mg/l. These categories of reclaimed water help minimize concerns over nitrate contamination of groundwater beneath sites where reclaimed water is applied.

How are reclaimed water quality standards used?

The reclaimed water quality standards lists the allowable uses of reclaimed water based on the class of reclaimed water produced (A.A.C. R18-11 Article 3, Table A, Minimum Reclaimed Water Quality Requirements for Direct Reuse). The reclaimed water quality standards also include rules for industrial reuse and use of reclaimed water for an unlisted type of direct reuse (not included in Table A).

The reclaimed water quality standards are used to classify wastewater treatment facilities as producing a particular class of reclaimed water (Class A+, A, B+, B, or C). This classification is included in the individual Aquifer Protection Permit (A.A.C. R18-9, Article 2) for the treatment facility, and includes the monitoring and reporting requirements for the particular class of reclaimed water. For a person or facility, other than a wastewater treatment plant, seeking to use reclaimed water, a reclaimed water permit is required (A.A.C. R18-9 Article 7). There are several types of general reclaimed water permits as well as an individual permit depending on the use and class of reclaimed water. Lastly, A.A.C. R18-9 Article 6 provides the requirements, including signage, pressures and locations, of reclaimed water conveyances – both pipelines or open water.

What are surface water quality standards?

Surface water quality standards (A.A.C. R18-11 Article 1) are state regulations or rules that protect lakes, rivers, streams and other surface water bodies from pollution. These rules contain beneficial use designations; numeric levels and narrative statements (water quality criteria) that are protective of the use designations; and procedures for applying the water quality criteria to wastewater discharges and other sources of pollution. Arizona’s surface water quality standards apply to all surface waters within the state (A.A.C. R18-11-101(41)), with the exception of those waters that are within Indian Country, as defined in 18 U.S.C. Section 1151. Surface waters include rivers, lakes, streams, wetlands, and reservoirs.

Beneficial uses include drinking water, fishing, aquatic and wildlife habitat, recreation, agriculture, irrigation and others. Water quality criteria are used to establish numeric and narrative standards necessary to protect and ensure that beneficial uses are attained. A surface water may have more than one designated use assigned to it and more than one standard for a given pollutant (e.g., arsenic) that applies based on the designated uses. When trying to decide which standard to use, always take the lowest and most protective based on the applicable designated uses. Under the surface water quality standards, all existing and designated uses shall be maintained and protected for all surface waters of the State. Surface water quality that is better than the applicable criteria must also be maintained and protected. These “antidegradation” protections apply to all surface water of the State.

The Clean Water Act requires that surface water quality standards be reviewed and updated, if necessary, every three years through a rulemaking process known as the “Triennial Review”. Proposed revisions to the standards are published for review by the public and local, state and federal agencies before beginning the formal state rulemaking process. Final action on the proposed rules is made by the Governor’s Regulatory Review Council.

How are SWQS used?

Surface water quality standards provide the regulatory basis for permit limits in the Arizona Pollutant Discharge Elimination System (AZPDES) permits to ensure standards are not exceeded in the receiving waters and designated uses are protected. Standards are also used to determine if the waterbody has good water quality. Waters that are meeting all standards and have a good biological community are considered to be supporting all their designated uses. Waters that are not meeting surface water quality standards are prioritized for further investigation and development of management strategies to bring the waterbody back to meetings standards to protect its designated uses.

Draft Implementation Procedures Documents

ADEQ has written four draft documents which provide background information on how the antidegradation, narrative bottom deposits, narrative nutrient standard for lakes and reservoirs, and the biocriteria rules were developed, their rationale, and how each is implemented through ADEQ water quality management programs: