To thousands of people who hike inside Farnsworth Metropark each year, the Bowling Green Fault is no secret: There’s even a marker along a paved trail showing where a portion of it exists near Waterville.

The marker, by Metroparks of the Toledo Area, states that the 100-mile fault — which goes from Findlay to southeast Michigan — is so close to the surface it can be visible to the human eye in that part of northwest Ohio when the Maumee River’s running low.

The presence of the fault and the location of it to Earth’s surface has emerged as a new issue in Houston-based Spectra Energy’s plan to build the $2 billion, 257-mile NEXUS Gas Transmission pipeline across Ohio. The project is being developed to move natural gas extracted from fracked shale in southern Ohio to southwest Ontario.

Spectra, developing the project with DTE Energy and others, has said in documents it provided to the Federal Energy Regulatory Commission that it believes the fault is 2,200 feet or more below Earth’s surface — nearly a half-mile. That information was used in the project’s final environmental impact statement, which asserts the proposed route does not include earthquake-prone areas.

But Andrew Kear, a Bowling Green State University assistant professor who specializes in geology and environmental policy issues, said at a rally Wednesday the Waterville area is one of the “worst possible” places for such a pipeline because of its seismic potential and porous karst geology.

“The time to act is now, before the pipeline goes in,” Mr. Kear said while standing near the banks of the Maumee River, outside the Roche de Boeuf visitors center, next to about 50 sign-carrying demonstrators. “If we’re having this problem here, what other problems are they having along the route?”

Mr. Kear was joined by Terry Lodge, a Toledo attorney representing a new citizens group, UC4POWER, which stands for United Communities for Protecting our Water and Elevating Power. Also joining them was Lisa Kochheiser, the group’s spokesman.

Mr. Lodge accused the pipeline company of “an astonishing screw-up.”

“When water is low, you can walk along the Maumee River next to the crack,” Mr. Lodge said.

The trio agreed they can’t understand why the company would have routed the pipeline so close to the fault and the city of Bowling Green’s water intake, which is in the Maumee.

“It’s a monumental mistake,” Ms. Kochheiser said. ”It’s difficult to imagine how they could have missed it.”

Spectra is soon expected to respond to a request for a hearing filed Feb. 1 by Mr. Lodge, who contends the project has been improperly sited and has put northwest Ohio at risk.

“They rushed the science on this part of it,” Mr. Kear said.

Spectra has said little about the new contention, which has drawn large crowds at recent Bowling Green city council meetings and those of other municipalities.

A company spokesman, Adam Parker, reiterated the company’s position last week that the pipeline will be built safely and without risk to the environment. He added in an email to The Blade the Federal Energy Regulatory Commission determined any impact because of the NEXUS project would be temporary and not significant.

“The NEXUS Project has undergone rigorous environmental review and has been evaluated publicly for more than two years to ensure that the project’s proposed design and construction will be conducted in accordance with all applicable state and federal regulations,” Mr. Parker said in an email to The Blade.

Mr. Lodge’s contention is based on a new study by Mr. Kear.

Spectra and others are planning a 36-inch transmission pipeline to move natural gas extracted from fracked shale in southern Ohio to southwestern Ontario, traversing 257 miles across northwest Ohio and southeast Michigan.

The project appears to be temporarily on hold because FERC’s five-member governing board no longer has a quorum. Previously down two commissioners, the resignation of a third took effect last Friday.

An alternative route that was considered would have added 41 miles to the project, Mr. Kear said.

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.

First Published February 9, 2017, 5:00 a.m.