New Mexico regulators on Thursday repealed and replaced portions of the “pit rule” intended to help manage wastes produced by oil and gas drilling.

The rule, which regulates oil and gas drilling waste pits, sumps and below-grade tanks, has been a source of contention between the industry and environmentalists, who have criticized Gov. Susana Martinez for siding with the view that regulations are too stringent, a position she took while campaigning for office.

Adopted in 2009, the rule required companies to line waste pits and remove waste from well sites as part of a closed-loop system. The intent was to prevent oil and gas drilling mud waste from leaching into groundwater.

The New Mexico Oil and Gas Association and the Independent Petroleum Producers Association filed requests to change the rule, saying it made drilling too expensive and created unnecessary paperwork, pushing producers from the state and costing New Mexico jobs and revenue.

Environmental and sportsmen organizations fought against any relaxation of the rule, saying it had been approved after negotiations with the industry and extensive deliberations.

In a 51-page order on Thursday, the New Mexico Oil Conservation Commission laid out its reasons for changing the pit rule, following testimony and deliberations that spanned more than a year.

The commission, appointed by the governor, said it found parts of the previous regulations were cumbersome. The commission also said the new rule offers some flexibility but not at the expense of water quality or public safety.

Most of the changes affect parts of the rule regulating waste pit permits, siting, design, construction and closure. The commission says the changes streamline and clarify the pit rule, making it easier for small-scale oil and gas operators to comply.

Changes to the rule include allowing more than one well to a waste pit and removing the requirement for operators to apply for a closed-loop system. The order also removes any requirement for a well driller to show impacts on soil, surface water and groundwater from waste pits or below-grade tanks.

The order also requires the Oil Conservation Division to act on applications under the pit rule within 60 days. If the division fails to make a decision, though, the application will be denied.

Environmental groups who opposed changes to the rule had not had time to review the order Thursday.

New Mexico has more than 80,000 pits, mostly in the southeastern and northwestern parts of the state.