The U.S. Environmental Protection Agency approved the application from the state of Arizona on September 15 that requested primary enforcement responsibility for all classes of injection wells under the Safe Drinking Water Act (SDWA).
The approval includes Class VI wells used to inject carbon dioxide (CO2) into deep rock formations.
The EPA's approval of the Underground Injection Control (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.
States having Class VI primacy already include North Dakota (2018), Wyoming (2020), Louisiana (2024), and West Virginia (2025). States that have applied and await Class VI primacy approval are Alabama, Alaska, Colorado, Mississippi, Nebraska, Oklahoma, Texas, and Utah.
More information on states delegating authority of Class IV wells to state can be found here.
Information from the EPA on primary enforcement for the UIC program can be found here.