The US Supreme Court has declined to hear an appeal from two Iowa counties seeking to enforce local regulations on a proposed carbon sequestration pipeline, dealing a setback to county-level efforts to assert greater control over pipeline development.
Story and Shelby counties had asked the high court to review a lower court ruling that found their local ordinances regulating hazardous materials pipelines were preempted by federal law. The Supreme Court denied the request without comment, allowing previous rulings in favor of Summit Carbon Solutions to stand.
The case centers on Summit’s proposal to build a multi-state carbon dioxide pipeline network designed to transport captured CO2 from ethanol plants for permanent underground storage. In October 2022, county supervisors in Story and Shelby counties adopted ordinances establishing local setback requirements, permitting rules, emergency management provisions and abandonment standards for pipelines operating within their jurisdictions.
Federal preemption and local authority
Summit Carbon Solutions sued later that year, arguing the county ordinances conflicted with federal pipeline safety regulations and state-level routing authority.
Federal courts agreed, with the US Court of Appeals for the Eighth Circuit upholding a December 2023 district court decision that local governments cannot impose regulations that interfere with federally regulated pipeline safety standards.
Following unsuccessful rehearing requests at the appeals court, county officials voted last August to elevate the issue to the Supreme Court. In a statement after the denial, the Shelby County Board of Supervisors said it was “surprised and disappointed” by the court’s decision and would consult legal counsel on possible next steps.
Relevant: Landowners Reject Summit Carbon’s “Rebrand” Amid Ongoing Pipeline Disputes
Summit Carbon Solutions declined to comment on the ruling. Industry advocates welcomed the decision, with American Carbon Alliance CEO Tom Buis saying it allows “important progress to continue” on projects that support ethanol production and agricultural markets.
The ruling comes as Iowa lawmakers again consider legislation related to eminent domain and carbon pipeline regulation.
Meanwhile, landowners opposed to the Summit project plan to lobby at the Iowa State Capitol, underscoring that the political debate over carbon sequestration infrastructure in the Midwest remains far from settled.
Read more: Carbon Pipeline Issue Expected To Shape Iowa 2026 Legislative Agenda
