Activists with the Potomac Riverkeeper Network set up at Paw Paw Tunnel Campground near Oldtown, Md., for a weekend paddle and protest over TransCanada’s planned natural gas pipeline. (Patricia Sullivan/The Washington Post)

The pipeline that TransCanada wants to build is short, 3.5 miles, cutting through the narrowest part of Maryland. It would duck briefly under the Potomac River at this 1,500-resident town, bringing what business leaders say is much-needed natural gas to the eastern panhandle of West Virginia.

But environmentalists say that brief stretch could jeopardize the water supply for about 6 million people, including most of the Washington-metropolitan area.

That’s why dozens of protesters have gathered each weekend this summer at various points along the upper Potomac, part of a growing national movement that opposes both oil and natural gas pipelines and wants businesses and governments to embrace green energy instead.

Inspired by the Dakota Access oil pipeline protest at Standing Rock, N.D., and the broad wave of demonstrations that has energized the left since President Trump’s inauguration, the protesters hope to persuade Maryland Gov. Larry Hogan (R) and his environment secretary to stop the pipeline, which got an enthusiastic green light from West Virginia.

“It’s got me worried,” said Andy Billotti, 53, who wore a T-shirt from April’s Peoples Climate March in Washington as he erected his tent at the Paw Paw Tunnel Campground near Oldtown, Md., for one recent protest. “If something were to happen, that fracked poison would come down the river . . . right into our wells.”

Andy Billotti, 53, was one of about 20 kayakers and canoeists who camped out at the Paw Paw campground. (Patricia Sullivan/The Washington Post)

Opponents gathered at the ­McCoys Ferry campsite in Clear Spring, Md., over the weekend and will be at Taylors Landing next weekend. The protest at Taylors Landing, near Sharpsburg, Md., is slated to include state Sen. Richard S. Madaleno Jr. (D-Montgomery), a gubernatorial candidate and the latest of a handful of politicians to take part.

The activists want Hogan, who this year banned fracking in Maryland, to deny TransCanada a water quality permit to cross the Potomac. Environment Secretary Ben Grumbles said the state has sought additional information about the project from the company and will schedule a public hearing on the permit application in coming weeks.

About 40 other permits are also needed, including ones from the Federal Energy Regulatory Commission and the National Park Service, because the pipeline would also go under the C&O Canal.

Industry and economic development officials say the pipeline is safe and sorely needed to attract new employers to the West Virginia panhandle.

“There are hundreds, if not thousands, of miles of gas lines like this in the Washington, D.C., area,” Eric Lewis, president of the Jefferson County Development Authority (JCDA), told about 60 protesters in July at a town council meeting in Shepherdstown, W.Va. “If people have issues with fracking, they should take it up somewhere else.”

West Virginia’s Public Service Commission already granted its utility, Mountaineer Gas, approval to begin building the distribution pipeline from Berkeley Springs to Martinsburg. Bulldozers are at work. The utility plans to eventually extend that line to Charles Town and Shepherdstown.

The natural gas that runs through the area’s existing pipeline is entirely spoken for since the opening of a Procter & Gamble manufacturing plant near Martinsburg, Mountaineer Gas officials said.

“You’ve got to have an industrial base to provide employment,” said West Virginia Commerce Secretary H. Wood Thrasher. “Without gas service, we are dead in the water.” He said the state has lost a “significant” number of companies interested in moving to the eastern panhandle because of the lack of natural gas service.

The JCDA has been working on getting natural gas service to the region for “decades,” said John Reisenweber, the authority’s executive director. More recently, it has encouraged the development of renewable green energy, such as wind and solar. But manufacturers, commercial and some residential developers insist on natural gas, he said.

While gas pipelines have crisscrossed the country since the 1920s, the number of approved interstate lines has spiked in recent years, driven by the boom in natural gas extraction through hydraulic fracturing. Protests have spiked, too.

New Yorkers convinced their state environmental agency twice in the past two years to deny a water quality certificate for natural gas pipelines. Federal authorities shut down a much-criticized Ohio pipeline in May, after 18 leaks spilled more than 2 million gallons of drilling fluid, adversely impacting the water quality. Catholic nuns near Lancaster, Pa., have built an outdoor chapel in an attempt to stop another pipeline.

In Virginia, two disputes over much larger proposed pipelines have become a hot-button political issue in the governor’s race.

The nation’s 2.3 million-mile pipeline network is considered the safest way to move oil, and the only feasible way to transport natural gas. Natural gas pipeline leaks are down 94 percent since 1984, the industry says. But accidents do happen — an average of 299 significant incidents in each of the past five years, according to federal data.

TransCanada spokesman Scott Castleman noted that his company and its predecessors have a century of experience in the region. The proposed eight-inch diameter pipeline would be buried up to 100 feet beneath the riverbed, with walls twice as thick as required, and constant monitoring for leaks and surges. A dozen TransCanada pipelines safely cross the Potomac River elsewhere in Maryland, Castleman said.

While solar, wind and other renewable energy sources­ are growing steadily, most authorities say it will be at least 2050 before renewables provide half or more of the nation’s energy needs.

Environmentalists, however, say there’s no sense in investing more in fossil fuels when wind and solar sources­ can provide energy now.

“More and more, people realize that each of these [pipeline] projects deepens our commitment to fossil fuels, locking us in for 40 or 50 more years,” said Bill McKibben, a well-known environmentalist and author. “The scientific verdict on natural gas has changed, and changed dramatically, in the past half-decade.”

The major component in natural gas is methane, which is significantly more efficient at trapping heat — and warming the planet — than carbon dioxide. A study published last year by Harvard University researchers found that emissions from methane have increased significantly since fracking began, although the researchers said they could not readily attribute the increase to fracking.

Members and friends of the Potomac Riverkeeper Network attended the July paddle to raise awareness about the pipeline project. (Reza A. Marvashti/for The Washington Post)

Environmentalists also point to the geology of the upper Potomac. The land beneath the river in this region is karst, a term for a terrain that is full of fractures, caves and pools, where special precautions are needed when building pipelines to avoid spillage of chemicals or gas into the water supply.

“Unless you have an X-ray of the ground, you never know where the water goes, or where it comes from,” said Stephanie Siemek, a doctoral student at the University of Maryland Center for Environmental Science’s Appalachian Laboratory in Frostburg, Md., who led a tour of the Paw Paw Tunnel for the environmentalists camping nearby in July. “You don’t know how old it is, or where it’s derived. It might start from a mountaintop, but we don’t know how it gets to a spring.”

About 20 people had come to the campground, some drawn by the opportunity to kayak or canoe down the river the next day, others by the cause.

“It wouldn’t make a difference until something happened, and then it would make a huge difference,” Janine Brewer of Frederick, Md., a retired federal employee, said as she strung her hammock between two pines.

Billotti, who joined the Standing Rock protest last winter, lives nearby in Burkittsville, Md. He runs along the C&O Canal, tubes in the river and takes his dogs for swims there, too.

“Why should Maryland pay the price for West Virginia’s growth?” he said. “We have clean energy available — they could build solar or wind power. We need to stop contaminating the planet.”