Proposed rule · 2026-05453

Colorado Underground Injection Control Program; Class VI Primacy

The U.S. Environmental Protection Agency (EPA or Agency) has received a complete Underground Injection Control (UIC) primacy application from the State of Colorado, requesting primary enforcement responsibility (primacy) for Class VI injection wells under the Safe Drinking Water Act (SDWA) section 1422. The EPA's approval of the State's UIC program primacy application would allow Colorado's Energy and Carbon Management Commission (ECMC) to issue and enforce compliance with UIC Class VI permits for injection wells used for geologic carbon sequestration. In this action, the EPA proposes to approve Colorado's application to implement the UIC program for Class VI injection wells located within the State, except those on Indian lands for which the EPA retains primacy. The EPA has determined that Colorado's UIC Class VI program meets federal requirements for primacy under SDWA section 1422 and the applicable implementing regulations in 40 CFR parts 144, 145, and 146.