TOLEDO, Ohio (AP) — Ohio's environmental regulators have more than doubled the proposed fines against a company building a natural gas pipeline from West Virginia to Michigan, saying Wednesday the two sides are at an impasse.

The fines now stand at $2.3 million and stem from what the Ohio Environmental Protection Agency says are numerous water and air pollution violations during construction of the $4.2 billion Rover Pipeline.

The twin pipelines are being built across Ohio to carry natural gas from Appalachian shale fields to Canada and states in the Midwest and the South.

Dallas-based develop...