In one of his last acts as president, Barack Obama finalized a rule protecting streams from surface mining operations. It is likely that, in one of his first acts as president, Donald Trump will overturn it.

The Stream Protection Rule is an update to existing mining regulations. It compels companies to restore the “physical form, hydrologic function, and ecological function” of streams after mining operations are complete. And, it calls for monitoring pollution levels in streams near surfaces mines.

In Appalachia, mining companies regularly blow the tops off mountains to access stores of coal beneath, a practice known as “mountaintop removal.” They dump the debris into valleys below, filling rivulets and contaminating downstream water supplies. Mining firms have decapitated more than 500 mountains in Appalachia and buried some 2,000 miles of streams, according to Appalachian Voices, an environmental advocacy group.

This poses a threat to wildlife and people who live nearby. Numerous studies link mountaintop removal to higher rates of cancer and heart disease among residents of neighboring communities.

A visualization of mountaintop removal. Source: Matthew Ross, Duke University

“I have seen the devastating impacts of coal mining firsthand. I have seen lakes turned gray downstream of mines. I have seen streams turned bright orange downstream of coal preparation plants,” said John Kinney, who works at Black Warrior Riverkeeper, an environmental group in Birmingham, Alabama.

The Stream Protection Rule wouldn’t stop mountaintop removal, but it would reduce its impacts, protecting an estimated 6,000 miles of streams over the next two decades.

“The rule spells out best practices for reclaiming land and reforesting with native species. It strengthens protections for ephemeral streams that are necessary for good water quality and quantity downstream,” said Davie Ransdell, a retired surface mine inspector for the state of Kentucky. “In my view, it’s also a job generator, since it prevents mining companies from just pushing material over the hill and into streams below.”

Lawmakers will likely vote Wednesday to overturn the rule, using the Congressional Review Act, which gives Congress the power to scrap executive actions issued in the last 60 working days.

“I would encourage the House to act quickly so that we can send this resolution to the president’s desk as soon as possible,” Senate Majority Leader Mitch McConnell (R-KY) said in a statement. Throughout his career, McConnell has opposed coal mining regulations. He also blamed what he called “Obama’s War on Coal” for the decline of the mining industry, although energy experts say it is largely the low cost of natural gas that is responsible for coal’s demise.

According to the Center for American Progress, the 27 representatives that sponsored or co-sponsored the Congressional Review Act bill received nearly $500 million from mining interests last year.

Environmentalists point out that the measure would prevent the Department of the Interior from issuing similar regulations in the future, hamstringing federal efforts to rein in pollution from coal mining operations that impacts communities not just Appalachia, but around the country.

“Water is a precious resource in the semi-arid West. It’s the lifeblood of agriculture,” Steve Charter, a rancher in Shepherd, Montana, said in a statement. “The Stream Protection Rule is an important step toward protecting ranches like mine and those of my neighbors, so we can stay on our land and pass it down to future generations.”

Mining operations threaten to halt the flow of streams and contaminate waters where people swim or fish. In Alaska, some communities depend on salmon fishing for their livelihood. Mining operations pose a risk to streams where salmon spawn. Elsewhere, citizens worry about drinking water and threats to tourism.

“My father and both grandfathers were coal miners, so I have lived in the shadow of the coal industry my entire life. With the birth of surface mining, the face of my beloved mountains has changed forever,” said Jane Branham, a lifelong resident of Wise County, Virginia. “Many are now working to build an ecotourism industry in our area, but all these efforts demand one crucial resource, namely clean streams. We must protect our streams because they are the lifeblood of our future.”

Jeremy Deaton writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art and culture. You can follow him at @deaton_jeremy.