A group representing county-level officials in Colorado has rejected an effort to change the siting rules for oil and natural gas development through the state legislature. The officials are also defending the existing rules, which were toughened in 2013 by state regulators.

“This process works and continues to work,” Colorado Counties Inc. (CCI) said in a legislative report to its members.

Under the 2013 regulations imposed by the Colorado Oil and Gas Conservation Commission (COGCC), drilling cannot take place within 1,000 feet of school buildings or other high-occupancy structures. The bill, HB 1256, would go even further, banning oil and gas drilling within 1,000 feet of a school’s property line. That’s a change that goes too far, according to critics of the measure.

The bill is championed by state Rep. Mike Foote (D) of Boulder County. For the past five years, the county has tried to block drilling by refusing to process local permits for activities tied to oil and natural gas development. Three cities in the county – Boulder, Longmont and Lafayette – also passed local ballot measures effectively banning oil and gas development.

But such bans have been found unlawful by the Colorado Supreme Court and the state’s attorney general, Cynthia Coffman (R), is now suing Boulder County to overturn the local permitting moratorium.

The state legislature should not try to rewrite the detailed regulations developed by the COGCC only four years ago, CCI said in a statement of opposition to HB 1256.

“CCI believes that the lengthy and robust rule making process undertaken at the COGCC included a wide variety of stakeholders and considered several setback options, ultimately agreeing upon the current 1000-foot setback from high occupancy buildings,” the group said. “[A]ny future proposed changes should be submitted to the COGCC so that all stakeholders may have the opportunity to negotiate once again.”

Representatives from the state’s energy sector have warned Foote’s bill could impose major restrictions on drilling in some of state’s most productive oil and gas fields. In Weld County, where most of the state’s drilling takes place, there are many schools that occupy 20 acres or more, Tracee Bentley, executive director of the Colorado Petroleum Council, said in testimony to a House committee.

“We believe the current setback established just four years ago by the [COGCC], with extensive stakeholder involvement, is working well, and avoids some of the pitfalls that this bill will create,” Bentley said, according to the Colorado Springs Gazette.

Democrats control the Colorado House and Foote’s bill passed that chamber last month in a party-line vote. During the debate, state Rep. Lori Saine (R) of Weld County said the measure threatened to prohibit new drilling in her district. “In Weld County, if you increase setbacks any more than they are now, it would ban drilling,” she said, according to the Longmont Times-Call.

Foote denied the measure is intended to ban drilling. But he has conceded the bill faces strong opposition in the Republican controlled state Senate, according to the Times-Call.