The Rocky Mountain region’s carbon capture and storage (CCS) landscape took two significant steps forward this spring. On March 19, 2026, the U.S. Environmental Protection Agency (EPA) published a proposed rule in the Federal Register to approve Colorado’s application for primary enforcement responsibility (“primacy”) over Class VI Underground Injection Control (UIC) wells under the Safe Drinking Water Act (SDWA). Just weeks later, in May 2026, the Colorado Energy and Carbon Management Commission (ECMC) and the Wyoming Department of Environmental Quality (WYDEQ) executed a Memorandum of Understanding (MOU) formalizing coordination on carbon storage projects that approach or cross the shared state line. Together, these developments signal that the Rocky Mountain West is rapidly maturing into one of the nation’s most organized regulatory environments for geologic carbon sequestration.
Background: Colorado’s Path to Primacy
Class VI wells are used to inject carbon dioxide (CO₂) into deep rock formations for permanent geologic sequestration, a cornerstone technology for decarbonizing industrial sources such as cement plants, power generation, ethanol production, and natural gas processing. By default, EPA administers the Class VI program; however, the SDWA allows states to assume primacy if they demonstrate that their programs meet or exceed federal requirements under 40 CFR Parts 144, 145, and 146.
Colorado’s pursuit of primacy has been several years in the making. In 2023, Senate Bills 23-285 and 23-016 expanded ECMC’s regulatory authority to include Class VI UIC wells and directed the agency to pursue primacy from EPA. The legislation also established comprehensive permitting, siting, and community engagement requirements, including financial assurance, cumulative impact analysis, surface owner consent, and protections for Disproportionately Impacted (DI) Communities. In 2024, House Bill 24-1346 clarified ECMC’s authority over geologic storage operations, confirmed that pore space is owned by surface owners, and created a mechanism for forming geologic storage units.
Following extensive stakeholder engagement, ECMC adopted Colorado’s Class VI UIC rules on December 16, 2024, with the state asserting that the rules meet or exceed federal standards while reflecting Colorado’s priorities for public health, safety, welfare, environmental stewardship, and wildlife protection. Colorado formally submitted its complete primacy application to the EPA on October 7, 2025.
EPA’s Proposed Approval
On March 16, 2026, EPA Administrator Lee Zeldin signed the proposed rule approving Colorado’s request, and the proposal was published in the Federal Register on March 19, 2026. EPA determined, subject to public comment, that Colorado’s program meets all applicable requirements for primacy approval under SDWA Section 1422. If finalized, the rule would authorize ECMC to issue and enforce Class VI permits for wells located within the state, except for wells on Indian lands, where EPA retains primacy.
EPA framed the proposal as part of its broader commitment to cooperative federalism and expedited UIC permitting, with EPA Regional Administrator Cyrus Western noting that Colorado has the local expertise to protect its groundwater resources while supporting economic growth. The public comment period ran through May 4, 2026, and EPA held a virtual public hearing on April 23, 2026. As of June 10, 2026, the EPA has not yet issued a final decision on Colorado’s Class VI primacy request.
If approved, Colorado would join a small but growing club of Class VI primacy states. To date, six states have received Class VI primacy. If approved, Colorado would join North Dakota and Wyoming as EPA Region 8 states with Class VI primacy. The practical significance is considerable: Project developers often view state primacy as a pathway to more efficient permitting than remaining in EPA’s federal queue, although permitting timelines still depend on project complexity and state implementation. Upon obtaining primacy, ECMC’s Class VI rules will apply prospectively to new operations and to existing EPA-issued Class VI permits in Colorado, unless otherwise specified in the rules.
Notably, Colorado’s program layers several state-specific requirements on top of the federal floor. Operators evaluating Class VI projects in Colorado should anticipate obligations that go beyond EPA’s baseline, including cumulative impacts analysis, enhanced community engagement (particularly for DI Communities), financial assurance requirements spanning the full project life cycle through post-injection site care, and unitization procedures for geologic storage resources.
The Colorado-Wyoming MOU: Geology Doesn’t Stop at the State Line
While primacy resolves the question of who permits a project, it does not resolve what happens when a CO₂ plume, or a project’s monitoring footprint, approaches a state boundary. CO₂ injected into deep saline formations migrates through subsurface pore networks that can extend for distances indifferent to political boundaries. State borders are fixed, but the geologic formations suitable for carbon sequestration are not.
Recognizing this, in May 2026 ECMC and WYDEQ executed an MOU to coordinate the permitting and oversight of carbon storage projects near their shared border. Key features of the agreement include:
Applicability
The MOU applies to projects located within one mile of the Colorado–Wyoming state line or where project activities may extend across it, encompassing project review areas, monitoring wells, facilities, and long-term site care activities.
Notification
The permitting state will notify its counterpart of covered projects, sharing key project details, timelines, and opportunities for input so that both states and operators are informed from the outset.
Consultation
The neighboring state may request consultation to exchange information, discuss potential impacts, and provide input, supporting early identification of issues and coordination on monitoring and oversight.
Preserved Authority
The MOU does not alter or limit either state’s regulatory authority. Each agency retains full responsibility for projects within its jurisdiction while committing to work in good faith on cross-border considerations.
Colorado Governor Jared Polis emphasized that the agreement is intended to speed up permitting, support cleaner air, and protect property rights, while officials in both states highlighted shared goals of protecting underground sources of drinking water (USDWs) and private landowner rights, and facilitating public engagement in border communities.
What this Means for Industry
For developers and pore space owners, these parallel developments carry several practical implications:
Faster, More Predictable Permitting
State primacy is widely expected to compress Class VI permitting timelines relative to EPA’s federal queue. Operators with prospective Colorado storage projects should monitor the final rule and prepare applications aligned with ECMC’s Series 800 Class VI rules rather than solely federal requirements.
A Higher Bar Than the Federal Floor
Colorado’s program includes state-specific elements including cumulative impacts, DI Community engagement, surface owner consent, and unitization. These requirement demand early planning, robust stakeholder strategies, and careful site characterization.
Reduced Cross-Border Uncertainty
The MOU gives developers of near-border projects a clearer roadmap for dual-state coordination, reducing the risk of late-stage regulatory surprises when plume modeling or monitoring networks extend toward (or across) the state line.
Regional Momentum
With Wyoming and North Dakota already holding primacy and Colorado poised to follow, the Rocky Mountain West offers an increasingly streamlined, state-led pathway for CCS deployment, which is an important consideration for project siting decisions and 45Q-driven investment.
Companies planning carbon capture and sequestration projects in Colorado or near the Colorado–Wyoming border should begin aligning project development plans, permitting strategies, and stakeholder engagement programs with the emerging state framework now, ahead of EPA’s final primacy decision.
If you would like to discuss Colorado’s proposed Class VI primacy, contact Trinity’s Denver Office at 720.638.7647.
