ADEQ Gains Primacy to Better Protect State’s Groundwater Quality

PHOENIX (Sept. 10, 2025) – The U.S. Environmental Protection Agency (EPA) has approved the Arizona Department of Environmental Quality (ADEQ) application to manage the federal Underground Injection Control (UIC) program in Arizona under the federal Safe Drinking Water Act (SDWA). This approval gives ADEQ the authority to issue permits, conduct inspections, and enforce federal requirements under the SDWA UIC program.

This is a major milestone for Arizona, said ADEQ Water Quality Division Director Trevor Baggiore. With primacy, we can make decisions faster and tailor oversight to Arizona’s unique groundwater conditions to better protect our water resources.

Arizona is the fifth state in the nation to receive primacy to regulate all classes of injection wells under the SDWA. ADEQ will now regulate the following types of wells:

• Class I: Deep wells for industrial and municipal waste
• Class II: Oil and gas production wells
• Class III: Mineral extraction wells
• Class V: Non-hazardous wells, such as stormwater or aquifer recharge
• Class VI: Carbon capture and storage wells

Class IV wells, which inject hazardous waste above or into usable aquifers, remain prohibited and are not allowed in Arizona or elsewhere under federal law.

ADEQ submitted its application to EPA Region 9 on Feb. 13, 2024, after years of collaboration. On May 15, 2025, EPA Administrator Lee Zeldin proposed final approval, recognizing Arizona’s readiness and program strength. EPA’s final approval now gives Arizona the authority to implement the UIC program in-state, allowing for:

• Faster, locally managed permit reviews
• More responsive oversight of groundwater protections
• A unified point of contact for regulated industries and stakeholders

ADEQ has met EPA’s strict standards, including having sufficient staff, legal authority, technical rules, and enforcement processes in place. ADEQ will soon begin the administrative process of updating current EPA-issued permits to reflect state oversight and regulatory references.

Injection well oversight is especially critical in Arizona, where groundwater plays a vital role in the state’s water supply.

To learn more about ADEQ’s UIC program | View Webpage >

Contacts

ADEQ Public Information Officer
Ph: 480-670-0568 (cell)
Email >