Maryland Capitol Police escort a woman who was arrested after protesting on the steps of the Statehouse on Wednesday. (Ovetta Wiggins/TWP)

Clean-water activists protested a planned natural gas pipeline on Wednesday, demanding from the steps of the Maryland State House that Gov. Larry Hogan (R) halt the project before the state loses the power to intervene.

But a spokeswoman for the governor says the issue is for the federal Army Corps of Engineers to decide.

About 30 environmentalists rallied outside the State House with Del. Jheanelle Wilkins (D-Montgomery) and Robbyn Lewis (D-Baltimore). Five women holding signs blocked an entrance to the complex for more than two hours until Capitol Police stepped in to arrest them.

Environmentalists spent much of last year trying to stop construction of the 3.5-mile pipeline beneath the Potomac River and C&O Canal in Western Maryland. They say the pipeline could jeopardize the drinking water supply of about 6 million people, many of them in the Washington metropolitan area.

Proponents of the pipeline, which would bring natural gas from Pennsylvania to West Virginia, say it would be safe and bring much-needed economic development to an area that is short on jobs.

Opponents faced a Thursday deadline to persuade Hogan to direct the Maryland Department of the Environment to do a state-based certification process under the federal Clean Water Act that would examine any potential impact on Maryland’s water system.

A spokesman for the state agency declined to say whether it would launch such an effort.

But Maryland Environment Secretary Ben Grumbles said in a statement that the agency will complete “a robust review” of the project as part of a separate state permitting process.

“We will insist that any energy facility or infrastructure project that moves forward complies with our state environmental safeguards,” Grumbles said.

Brooke Harper, policy director for Chesapeake Climate Action Network, which organized the protest, said police did not intervene until the protesters said they planned to move to the governor’s mansion.

Hogan spokeswoman Amelia Chasse said the governor “supports all Marylanders’ right to advocate for their views; however, these protesters appear to have the wrong address.”

“This issue is under the purview of the federal Army Corps of Engineers, not our administration,” Chasse said. “The Maryland Department of the Environment has and will continue to ensure that Maryland’s environmental standards are upheld.”

Denise Robbins, communications director for the climate network, said many activists feel betrayed by Hogan, who earned some credit with environmentalists last year when he signed a law banning hydraulic fracturing in the state.

Now, she said, he is “going back on his promise to protect Maryland from the risks of fracking.”

The pipeline would not involve fracking in Maryland.