The Pennsylvania Department of Environmental Protection (DEP) on Thursday unveiled draft regulations aimed at curbing smog-forming emissions from existing oil and natural gas production and midstream operations.

The proposal mirrors Obama-era guidelines for the industry issued in 2016 for limiting emissions of volatile organic compounds (VOC) from older industry sources, part of which the Trump administration is considering rolling back. The rules would apply to storage tanks, pneumatic controllers and pumps, and certain kinds of compressors at natural gas processing plants, other midstream facilities and well sites, according to documents prepared for a meeting with the Air Quality Technical Advisory Committee (AQTAC).

Operators would also be required to conduct more stringent leak monitoring and repair quarterly at well sites, gathering and boosting stations, and processing plants.

DEP said that despite an U.S. Environmental Protection Agency (EPA) proposal to withdraw some VOC guidelines, the state plans to move forward with the regulations for existing sources. Earlier this year, the DEP submitted comments to the EPA opposing the withdrawal.

The Marcellus Shale Coalition (MSC) said while its members are concerned about the price tag of any new requirements, more pressing questions loom about DEP’s legal authority to advance the rules, given the federal government’s stance.

“While we’re still reviewing the proposal, we do have initial concerns about potential costs as well as DEP’s timing given ongoing federal regulatory activity associated with existing source emissions,” President David Spigelmyer said. “That said, Pennsylvania’s continued success in enhancing air quality, as reflected by DEP’s own data, is occurring alongside and largely due to the Commonwealth’s leading natural gas production position. Again, rather than creating more regulatory uncertainty, it would be prudent for DEP to delay any regulatory proposals until federal rules are finalized.”

While year/year methane emissions and VOCs from unconventional gas well sites and midstream facilities in Pennsylvania increased in 2015, several other pollutants dropped considerably, according to DEP’s latest air emissions inventory. Documents presented to the AQTAC indicated the draft regulations for existing sources would target not only VOC emissions, but they would help reduce methane as a “co-benefit” since both are generated by oil and gas operations.

If the package were to become reality, it would come after DEP implemented in August more robust permitting requirements for new unconventional gas wells and some midstream facilities that were aimed at better controlling methane emissions and other pollution sources, such as VOCs and nitrogen oxides. The steps are part of Gov. Tom Wolf’s broader plan to reduce industry emissions. The proposed rules were hailed by environmental groups.

“Gov. Wolf’s leadership on methane and his recent victory at the polls confirm once again that Pennsylvanians want sensible protections from oil and gas pollution,” said Environmental Defense Fund President Fred Krupp, referring to Wolf’s victory in November for a second term. “The proposal to bring thousands of existing oil and gas facilities under sensible safeguards will help ensure that communities across the state enjoy cleaner, healthier air, and serves as a crucial backstop against efforts in Washington to undue core climate protections.”

Pennsylvania produced 5.4 Tcf of gas last year and is on track to exit 2018 producing 6 Tcf, second only to Texas in nationwide production. Ohio regulators last month also announced plans for more industry air emissions regulations based in part of the Obama-era rules.