The proposal could accelerate the permitting process for projects in the state, including carbon capture and storage (CCS) projects.
The US Environmental Protection Agency (EPA) has proposed a significant regulatory change that could expedite permitting for Underground Injection Control (UIC) wells in Arizona. A proposed rule published on May 19, 2025, would grant the Arizona Department of Environmental Quality (ADEQ) primary enforcement authority, or “primacy,” for permitting Class I-VI UIC wells under the federal Safe Drinking Water Act (SDWA).
The SDWA covers six classes of injection wells, each designed for specific purposes: Class I for deep waste disposal; Class II for oil and gas production fluids (commonly known as Enhanced Oil Recovery or “EOR”); Class III for mineral extraction; Class IV for hazardous waste in groundwater cleanup; Class V for non-hazardous fluid disposal; and Class VI for carbon dioxide storage.
Arizona would become the fifth state to have primary permitting authority for all well classes, following Louisiana, North Dakota, West Virginia, and Wyoming. Most recently, on February 18, 2025, EPA granted primacy to West Virginia for Class VI wells (for more details, see our blog post).
Proposed Rule: Primary Permitting Authority for Arizona
Arizona’s petition for primacy follows the adoption of state legislation and development of a state program intended to meet or exceed EPA’s UIC regulations. If approved, the ADEQ will assume responsibility for issuing and managing UIC permits, potentially accelerating the permitting process. This shift is expected to leverage the ADEQ’s local expertise and resources, enabling more efficient project approvals tailored to the state’s geological landscape and economic development goals.
The proposal has garnered strong support from Arizona officials, including Governor Katie Hobbs and US Congressmen Andy Biggs, Juan Ciscomani, and Paul Gosar. Advocates of the proposed rule underscore the potential economic and environmental benefits of granting primacy to Arizona.
EPA is inviting public comments on the proposed rule until July 3, 2025, and will hold a public hearing on June 25, 2025. Interested stakeholders can utilize these opportunities to engage with regulators, present any concerns, and/or support the rule.
A Broader Trend: Other States Pursuing Primacy
Arizona is not alone in seeking primacy for UIC wells. Other states are in various stages of pre-application activities for different UIC well classes, including Alabama, Alaska, Colorado, Mississippi, Nebraska, and Utah. Texas is seeking primacy for Class VI UIC permits, with an EPA proposed rule expected soon.
These efforts reflect a growing recognition of the importance of state-level management in advancing projects requiring UIC wells. By obtaining primacy, states can tailor regulatory frameworks to their specific needs, potentially leading to more effective and efficient project permitting, project implementation, and emissions reductions.
The proposed rule for Arizona represents another step forward for the CCS industry. We will continue to monitor and report on these developments.
