Protesters gather outside the Maryland Statehouse to express concerns about fracking. (Nikki Kahn/The Washington Post)

Lawmakers in Prince George’s County voted unanimously on Tuesday to ban hydraulic fracking, becoming the first local jurisdiction in Maryland to prohibit the extraction of natural gas within its borders since the state’s moratorium on the practice went into effect.

Council member Mary A. Lehman (D-Laurel) sponsored the legislation that would amend the zoning ordinance to forbid natural-gas drilling across the county and particularly in the rural southern Prince George’s communities sitting on top of the Taylorsville Basin.

The basin — which runs through southern Maryland under the Potomac River and into Virginia — is a potentially untapped natural-gas reserve, according to the U.S. Geological Survey. But it spans an ecologically sensitive area that residents and activists have long fought to protect from excessive development, industry and power plants.

“We are taking a lead in the state to protect our quality of life here,” Lehman said after the council adopted the ban. “It will lay the groundwork for a statewide ban in Maryland.”

Supporters, including Gov. Larry Hogan (R), have called fracking an “economic gold mine” that would create hundreds of jobs and provide a clean source of cheap energy. But anti-fracking activists say the extraction method exposes the environment to the risk of spills, water and air pollution and potentially irreversible ecological damage.

Hogan’s predecessor, former governor Martin J. O’Malley (D), barred fracking until a commission could study the public-health and environmental impacts. The commission’s controversial 2014 report found that natural gas could be produced safely. Nevertheless, the Democratic-controlled legislature pushed for fracking restrictions against Hogan’s wishes.

Last year, state lawmakers proposed a two-year moratorium on hydraulic fracturing, which involves blasting pressurized water and chemicals into rock to extract gas. Regulators are studying the practice, and the law required they adopt rules before issuing permits for drilling in places such as Western Maryland, home to a huge shale rock formation.

The bill became law without Hogan’s signature.

Activists are hoping the Prince George’s ban will trigger a trend across the state and that the movement will motivate lawmakers in Annapolis to adopt a prohibition before the moratorium expires in October 2017.

“It’s important for Prince George’s to protect its residents from fracking,” said Thomas Meyer, senior organizer for the environmental group Food & Water Watch. His non-governmental organization, along with residents and other groups, brought the idea of a ban to Lehman in the summer. “We hope the Maryland legislature follows suit.”

Drew Combs, of the Maryland Petroleum Council, played down the significance of the ban, saying the amount of gas in Prince George’s is negligible compared to reserves in the Marcellus rock formation in Garrett and Allegany counties.

“While this decision is largely symbolic, it sends the wrong message,” he said. “Prince George’s County residents benefit year-round from natural gas safely produced in neighboring states.”

The county is following in the footsteps of towns in New York, which also used their local zoning ordinances to prohibit fracking. The energy industry sued, saying the local governments lacked the authority to issue such bans, but the state’s highest court upheld the “home rule” of municipalities in 2014.

The ruling had a domino effect across the country as local governments, such as the District, issued a variety of resolutions, laws and ordinances against hydraulic fracturing. In Montgomery County, lawmakers adopted a 2014 resolution opposing fracking in Virginia’s George Washington National Forest, which lies in the Potomac River basin. Lawmakers wanted the effects on water supply studied first.

For Prince George’s County resident and civic leader Joanne Flynn, the ban could not come soon enough. The Brandywine-area farmer depends on well water for drinking, for her crops and her livestock. Fracking, she said, would endanger her entire livelihood.

“This would protect our future,” Flynn said at the council hearing on Tuesday. “We need to address climate change in all we do.”