As mandated by the Safe Drinking Water Act of 1974 (as amended), the United States Environmental Protection Agency (EPA) has promulgated regulations establishing minimum requirements, technical criteria, and standards for State Underground Injection Control (UIC) programs to protect underground sources of drinking water (USDW). The SDWA charges EPA with the administration of the UIC program, including the promulgation of regulations and the authority to grant primacy to qualifying, individual states. Statutory authority for the UIC program can be found at 42 U.S.C. §300h et seq.

ADEQ submitted an application for UIC primacy to EPA Region 9 on February 13, 2024. Since that time, it has been reviewed and forwarded on to EPA Headquarters for final review and approval. Once granted primacy, ADEQ will begin administering UIC permits within Arizona state jurisdiction. The Arizona UIC Program will regulate Class I, Class II, Class III Class V, and Class VI injection wells. Class IV injection wells that dispose of hazardous waste into or above any usable aquifer will be prohibited. ADEQ plans to administratively modify the current EPA permits soon after primacy, updating references to federal regulations to the state regulations, amongst other administrative changes. ADEQ will work closely with permittees and will submit a public notice of the modifications when ready in accordance with applicable requirements.

Stakeholder Materials

ADEQ held several stakeholder meetings during the rulemaking establishing UIC rules in the Arizona Administrative Code and in preparation for the submission of the UIC primacy application to EPA. To see post-stakeholder meeting information and workgroup recordings or updates, as well as draft rules and other products, visit the dedicated stakeholder engagement page | View Page >

Primacy Application Public Notice

In order to apply for primacy of the UIC program for lands under state jurisdiction within Arizona, ADEQ is required under 40 CFR 145.31(a) to issue public notice of its imminent intent to apply for primacy. 40 CFR 145.31(a)(2) requires ADEQ to indicate when and where the State’s proposed program submission may be reviewed by the public.

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For future ADEQ communications and outreach regarding the UIC program, sign up for email notifications. When selecting subscription topics, select Water Quality, proceed to the next page(s), and then select UIC Primacy Stakeholder Communications where listed | Subscribe >

Update (Feb. 13, 2024):  The UIC Primacy Application has been submitted to the EPA Region 9 for review and approval. After completing its review, Region 9 forwarded the application to EPA Headquarters for final review.

Update (May 19, 2025): EPA is seeking public input on their intent to approve Arizona’s request for primacy for the UIC program under the Safe Drinking Water Act (SDWA) section 1422. 

• Comment on EPA Proposed Rulemaking: Arizona Underground Injection Control Primacy Program | View > 
• Public Hearing for EPA Proposed Rulemaking: Arizona Underground Injection Control Primacy Program | View > 

As a result of EPA’s comprehensive review of the state’s application, the Agency is proposing to approve Arizona’s primacy application because EPA has determined that the application meets all applicable requirements for primacy approval under SDWA section 1422 and because the State has demonstrated that it is prepared to implement a UIC program in a manner consistent with the terms and purposes of SDWA and all applicable UIC regulations. Upon approval, EPA would oversee Arizona’s administration of its UIC program.

EPA requests that written comments be submitted on or before July 3, 2025, via the Federal eRulemaking Portal for Docket ID No. EPA-HQ-OW-2025-0087 | View Portal >

All material associated with this action can be found in the Docket.