Two oil and natural gas industry groups on Tuesday filed a lawsuit challenging rules established in Thornton, CO, about seven miles north of Denver, claiming they conflict with existing state regulations for energy extraction.

The Thornton City Council six weeks ago enacted rules that exceed regulations established by the Colorado Oil and Gas Conservation Commission (COGCC), according to the lawsuit filed in the Adams County District Court by the Colorado Oil and Gas Association (COGA) and American Petroleum Institute (API).

Thornton now requires a 750-foot buffer between wells and homes, and restricts abandoned flowlines, exceeding state requirements. COGCC had warned Thornton officials in advance that the proposed rules would illegally preempt state law.

COGA also sent several letters to the Thornton City Council in advance of its vote, expressing “serious legal concerns” about the draft rules. “Those concerns were ignored, making it necessary to challenge Thornton’s regulations in court,” said COGA CEO Dan Haley.

Last year, following a detailed stakeholder process, Colorado regulators approved oil and gas rules for urban areas, Haley said.

“Those new rules have only just come into effect and need time to be put into practice,” he said. “As Colorado’s Front Range communities grow and expand over a resource basin with more than a century of active energy development, it’s important that the vast amount of regulations already on the books are better understood, that we keep communications open, and that we look for opportunities to work together.”

In their joint court filing to the state district court, COGA and API argue that Thornton is “impliedly preempted from regulating the safety aspects of gas gathering pipelines.” They contend that Thornton’s rules are all “preempted and invalid,” covering well setbacks waivers, flowline standards, general liability insurance standards, surface disturbance standards, and gathering pipeline provisions/standards.

COGA has challenged other local attempts to establish oil and gas restrictions that exceed state standards, including in Adams and Weld counties.

Meanwhile, on Tuesday the Longmont City Council agreed to sign on to a letter by the town of Broomfield to Gov. John Hickenlooper and the COGCC urging them to work with cities to provide stronger local rules regarding health and safety issues in the oil and gas sector. Some citizens asked for the Longmont council to re-impose a now defunct ban on hydraulic fracturing (fracking).

Broomfield has invited other local governments to co-sign the letter, including Adams County, Lafayette, Boulder, Boulder County, Thornton, Westminster, Fort Collins, Louisville, and Erie.