Final rule · 2025-17769

Arizona Underground Injection Control (UIC) Program; Class I-VI Primacy

The U.S. Environmental Protection Agency (EPA) is approving an application from the State of Arizona (the State) that requests primary enforcement responsibility (primacy) for Class I-VI injection wells under the Safe Drinking Water Act (SDWA) section 1422. The EPA's approval of the State's UIC program primacy application will allow the Arizona Department of Environmental Quality (ADEQ) to authorize underground injection for all underground injection wells regulated under the SDWA within the State's jurisdiction and ensure compliance with UIC program requirements. The EPA will remain the permitting authority for all well classes on Indian lands within the State, except for Class II wells on Navajo Indian lands for which the EPA has granted the Navajo Nation primacy for the SDWA Class II UIC program.