Will Hackman of the District on the Potomac River. A natural gas pipeline known as the Potomac Pipeline has drawn opposition from activists for years. (Reza A. Marvashti/For The Washington Post)

Maryland officials voted Wednesday to block Columbia Gas from using state land to build a natural gas pipeline that activists have been fighting for two years.

The unanimous vote by the Board of Public Works, which includes Gov. Larry Hogan (R), came after more than 60 members of the General Assembly wrote a letter urging the board to deny a request from Columbia Gas to construct a distribution line under the Western Maryland Rail Trail.

The board’s decision presents a serious hurdle for the project, which had been approved by federal and state regulatory agencies.

Columbia Gas, a subsidiary of TransCanada, could challenge the board’s decision. The company “will consider our options over the coming days to keep this project on track,” spokesman Scott Castleman wrote in an email.

“Today’s vote denying our easement request is unfortunate,” Castleman wrote. “That being said, it does not change the need for, or the company’s commitment to, our Eastern Panhandle Expansion Project.”

The 3.5-mile pipeline, known as the “Potomac Pipeline,” would bring natural gas from Pennsylvania to West Virginia, bisecting the narrowest slice of Maryland’s panhandle and running beneath the Potomac River and Chesapeake and Ohio Canal in Western Maryland.

Maryland Gov. Larry Hogan (R). (Michael Robinson Chavez/The Washington Post)

Castleman called the pipeline “critical” for West Virginia’s eastern panhandle and said an extensive review process has “confirmed that through proper design and construction our project can be completed in an environmentally responsible and safe manner.”

Environmentalists said the pipeline could jeopardize the drinking water supply of about 6 million people, many of them in the Washington area, even though the proposed Maryland route is about 100 miles from the District.

Opponents of the pipeline who came to the Board of Public Works meeting Wednesday in Annapolis applauded after the final vote.

“They agreed to protect the public,” said Barbara Stiefel, an activist from West Virginia, referring to Hogan, Comptroller Peter Franchot and Treasurer Nancy K. Kopp, who make up the Board of Public Works.

Franchot, a Democrat, said the board found testimony from activists, who spoke at a public hearing in December, “compelling.”

“We were being asked to jeopardize the environment and not get any economic benefits,” Franchot said in an interview following the vote. He called the unanimous vote “a great victory.”

In brief remarks, Hogan said the board’s decision “had nothing to do with any letter from the legislature.” The governor said he had to leave the board meeting last month early but had thought the easement request had been voted against then. Instead, the vote was deferred until Wednesday’s meeting.

“We were always going to have a 3-nothing vote,” Hogan said.

In a letter sent to the Board of Public Works on Tuesday, state senators and delegates said the pipeline would “reverse course on our state’s efforts to protect the health of our residents and combat climate change.”

“Moreover, enabling fossil fuel production runs counter to our state’s goals of increasing renewable energy production,” the legislators wrote.

Some activists expressed surprise that Hogan joined Franchot and Kopp in voting against the easement, noting that he did not halt the project when they requested he do so last year. At the time, Hogan’s office said the issue was for the Army Corps of Engineers to decide.

Ann Bristow, an activist with the group Frack-Free Frostburg, said she was pleasantly surprised by Hogan’s vote. She compared it to his 2017 decision to call for a ban on fracking, after previously supporting it. He said then that he had changed his mind because he didn’t believe it could be done in an environmentally sensitive manner.

“He saw the writing on the wall — he wants to be on the right side of history,” she said.

Meanwhile, environmental activists in Virginia have been waging their own fight against two fracked gas pipelines proposed to run through rural sections of that state.

Opponents of the proposed Atlantic Coast Pipeline have won a string of legal victories that have brought work on the $7 billion, 600-mile natural gas pipeline to a halt, at least temporarily. Several rulings are under appeal, while an even bigger case looms in the new year.

That project, spearheaded by Dominion Energy, would carry fracked natural gas through rugged mountain terrain and several national forests from West Virginia through central Virginia and into North Carolina.

A different pipeline, Mountain Valley Pipeline, would carry natural gas 300 miles from West Virginia through some of Virginia’s most rugged mountains and into North Carolina. It is being built by a consortium of companies led by EQT Midstream Partners of Pittsburgh but has also faced several setbacks, including a lawsuit filed last month by Virginia Attorney General Mark R. Herring (D).