Rover Pipeline LLC construction activities in Washtenaw County, MI, may be partially to blame for petroleum-laced water being discharged into nearby wetlands, according to the Michigan Department of Environmental Quality (MDEQ).

In a letter to the developers Friday, MDEQ said it received a complaint of "a petroleum odor coming from water discharged from the Rover Pipeline Project." Staff inspected the site and "noted a petroleum odor and observed a sheen in" a Rover dewatering enclosure, the agency said.

MDEQ said a former gas station is the likely source of the petroleum observed in the discharge and that the dewatering process being used during Rover's construction "may be exacerbating the spread of the contaminated groundwater."

The agency said the petroleum contamination means Rover needs to obtain a National Pollutant Discharge Elimination System permit and treat the water prior to discharging it. MDEQ asked Rover to respond this week with a plan to address the issue.

The 713-mile, 3.25 Bcf/d Rover has drawn plenty of scrutiny from environmental regulators since it began construction earlier this year. An inadvertent release of a horizontal directional drilling (HDD) mud into a wetland near the Tuscarawas River in Ohio led to delays for Rover after FERC ordered an independent review of the incident.

Meanwhile, the Ohio Environmental Protection Agency, citing multiple alleged environmental violations, has been pursuing more than $2 million in civil penalties from Rover, which the company has challenged.

The West Virginia Department of Environmental Protection has also cited Rover for water pollution violations allegedly occurring during construction in that state.

Rover, expected to open up a significant new route for Marcellus and Utica shale gas to reach markets in the Midwest, Gulf Coast and Canada, began partial service in September. The pipeline has been delivering roughly 1 Bcf/d east-to-west from Cadiz, OH, to interconnects with Panhandle Eastern and ANR, according to NGI's daily Rover Tracker.

With FERC now allowing HDD work to resume at multiple sites along the project route, backer Energy Transfer Partners LP plans to have Rover completed and in-service by the end of 1Q2018.