A Halliburton wellhead is visible at a fracking site in Midland, Tex. (Steve Gonzales/Houston Chronicle/AP)

On the last business day of the year, the Interior Department rescinded a 2015 Obama administration rule that would have set new environmental limitations on hydraulic fracturing, or fracking, on public lands.

The regulation from the Bureau of Land Management, which had been opposed by the oil and gas industry and tied up in court, would have tightened standards for well construction and wastewater management, required the disclosure of the chemicals contained in fracking fluids, and probably driven up the cost for many fracking activities.

It had been held up in litigation and had not taken effect; a Wyoming district court said it exceeded the agency’s authority. Reversing the regulation, the Interior Department says, clears up that legal question and also lifts a costly regulation for the industry, in line with President Trump’s agenda to slash regulations and advance the United States’ “energy dominance.”

The agency said rescinding the rule would save “up to $9,690 per well or approximately $14 million to $34 million per year” in industry compliance costs. It also noted that because of state, tribal and existing federal regulations, the move “would not leave hydraulic fracturing operations unregulated.”

But Mike Freeman, an attorney with EarthJustice who defended the now-repealed regulation in court, countered that it “was a reasonable and long overdue update of the agency’s old regulations, adopted in the early 1980s, about 35 years ago, and they were developed long before modern fracking became common.”

“The move today represents just another example of the Trump administration sacrificing our public lands, air and water in order to pad the bottom line of oil and gas companies,” Freeman said.

Industry groups, however, hailed the decision.

“Adding a layer of duplicative federal regulations does not improve on the success of existing state and federal regulations,” said Erik Milito, group director of upstream and industry operations at the American Petroleum Institute, in a statement. “If the rule were allowed to continue, development in several states, such as New Mexico, Colorado, and Wyoming, could have been especially hard hit with slowed permitting and limited access to public lands, stunting economic growth and pushing away jobs.”

Hydraulic fracturing is the process by which oil and gas firms first drill wells that run not only vertically downward, but also horizontally within the ground — and then blast enormous volumes of water down the wells to crack open rock layers and unleash oil or natural gas. The technology has been transformational for the industry, driving down the price of natural gas dramatically and so upending the electric power industry, while also turning the U.S. into a top global oil producer.

But it has also raised many environmental concerns, including that fracking fluids could pollute water supplies and that the flowback fluids or liquids that reemerge from the earth after hydrocarbons are released may be improperly stored and get into waterways.

The precise extent to which fracking operations pollute waterways has been hotly debated. Last year, the Science Advisory Board sent a review to the Environmental Protection Agency faulting the agency for finding a lack of “widespread, systemic impacts on drinking water resources in the United States,” determining that the EPA had not provided “quantitative analysis” to support that conclusion.

The current decision only affects public lands — which are only a fraction of the total area used in fracking activities but a significant one.

“They’re important for wildlife, important for public use, and they’re some of the last best places in this country,” Freeman said.