In the July 12, 2017, photo above, clean water, left, and muddy water from the construction of the Rover multi-state natural gas pipeline seep into a creek in New Washington, Ohio.

(AP Photo/Tony Dejak)

At a Glance

A pipeline being built in Ohio has lost 146,000 gallons of drilling fluid near a river. The liquid is a mixture of water and bentonite clay. It disappeared in the same spot as a similar incident that caused a nearby wetland to become clogged with waste.The fluid from this recent event has yet to surface, and environmentalists aren't certain where it will wind up.

A controversial pipeline being built in Ohio has raised the concerns of environmentalists after it lost 146,000 gallons of drilling fluid near a river.

, an ongoing project from the Energy Transfer Partners (ETP), which built the disputed Dakota Access Pipeline, Kallanish Energy reports. The Ohio Environmental Protection Agency (EPA) discovered the spill on Jan. 10 near the Tuscarawas River in Stark County.

ETP emphasized that the incident, known as a loss of return, is not a spill. A loss of return occurs when the drilling fluid, awater and bentonite clay mixture used to lubricate the blades, does not flow back up the pilot hole and instead surfaces into one or more geological formations.

EPA officials say theyaren’t certain where the liquid will wind up.

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However, they suspect it will appear on a wetland near the river, which was the result of a similar incident in April 2017. The loss occurred in the same spot as this recent one, , according to an April 2017 violation notice sent by the EPA.

“ concerning these concerns and the agency is determined to fulfill our role in protecting human health and the environment,” EPA media contact James Lee told Earther.

being done to build underneath highways and rivers, but crews resumed working in December, according to Reuters.

When it is completed, the $4.2 billion pipeline will transport up to 3.25 billion cubic feet from Ohio, Pennsylvania and West Virginia to the Midwest and Ontario, Canada, daily, Reuters reports. Construction is expected to be finished by the end of the first quarter.

ETP says it has been flying drones over the site of the loss of return to monitor for impacts, according to EcoWatch.