Colorado regulators on Thursday moved to expand oversight on oil and natural gas wellsites by proposing to step up inspections and place limits on greenhouse gas (GHG) emissions.

Following three days of hearings, the Colorado Air Quality Control Commission (AQCC) approved the emission controls, which were put in place by omnibus legislation enacted earlier this year.

The rules now will undergo public hearings. They were issued in response to the U.S. Environmental Protection Agency’s intention to declare nine counties in the Denver metropolitan area and along the Front Range as being in “serious” violation of federal ozone standards.

In response to the new rules, Colorado Oil and Gas Association CEO Dan Haley and Colorado Petroleum Council executive director Lynn Granger said separately the state’s air quality has been improving, and the oil and gas industry deserves some of the credit.

“Conversations about complicated technologies and emission reductions need to be steeped in facts, not scare tactics or suppositions,” said Haley. He said the tougher rules could “significantly increase costs” for small operators with no emissions benefits.

“Our state has been a national leader in comprehensive air rules, and the oil and gas industry has always been willing to come to the table.” The regulatory staff’s tone was “strident and anti-industry,” which is a “striking departure from how we’ve done business in Colorado in the past.”

Granger added that “the rushed nature of this rulemaking did not allow for a robust stakeholder process on all of the complex topics addressed. Instead, this rulemaking will likely result in significant unintended consequences.”

The Environmental Defense Fund (EDF) praised the rules, which it said would protect Colorado’s air and climate from oil and gas pollution.

EDF’s Matt Garrington, state campaigns manager, said that Colorado in 2014 was the first state to regulate oil and gas industry methane emissions and it has reduced leaks on the Front Range. With the new rules, EDF has calculated that Colorado still faces a “significant gap” between 2030 GHG emission projections and the reductions required by state law.