Energy Transfer Partners LP’s Rover pipeline, the biggest natural gas pipeline under construction in the United States, received more bad news after West Virginia told the company to stop some work, citing environmental violations, regulators said.

The $4.2 billion pipeline already faces sanctions for violations in Ohio and a federal ban on drilling activity that has delayed the anticipated startup of the project’s first phase to the late summer from July.

West Virginia’s Department of Environmental Protection (DEP) issued the order to stop activity in certain areas on July 17, which was made public in a US Federal Energy Regulatory Commission filing. The state, in the filing, noted sediment deposits and improper erosion controls, along with other violations.

ETP said it still expected the second and final phase of the project to start up in November.

"We are complying with the DEP, and have stopped construction at the areas noted in the order. We do not anticipate any changes to our timeline," ETP spokeswoman Alexis Daniel said.

The line from Pennsylvania to the Canadian province of Ontario will be able to carry up to 3.25 billion cubic feet (bcf) per day of gas from the Marcellus and Utica shale fields in Pennsylvania, Ohio and West Virginia. One bcf of gas is enough to power about 5 million US homes.

In a note, Barclays commodities analyst Nicholas Potter said Rover’s exact date when service would start was a "moving target," saying "meaningful volumes" were not expected until 2018.