On September 10, the US Environmental Protection Agency (EPA) authorized the Arizona Department of Environmental Quality (ADEQ) to regulate all underground injection of carbon dioxide for long-term geological sequestration within Arizona’s jurisdiction. The final rule followed a comprehensive technical and legal review to ensure the state’s Underground Injection Control (UIC) program met all requirements under the Safe Drinking Water Act (SDWA) section 1422. As discussed in an earlier post, Arizona previously did not have primacy over any UIC well classes, unlike other states that have sought Class VI primacy thus far.

With this final rule, ADEQ will now regulate permitting, compliance, and enforcement for all six well classes in Arizona. EPA will retain oversight for wells on Indian lands, except for Class II wells on Navajo Nation lands, where primacy already exists.

This marks the fifth state with Class VI primacy, joining North Dakota (granted primacy in 2018), Wyoming (2020), Louisiana (2023), and West Virginia (2025). As we previously reported, EPA proposed to grant Class VI primacy to Texas in June and is expected to finalize that proposal in the near term.

Although there are no pending Class VI permit applications for projects in Arizona, Arizona is now better positioned to attract investments in CCS.

further contributions to the article by Manasvini Venkatesh*

*Manasvini Venkatesh is not a lawyer.