ROANOKE, Va. — The lead partner in the Mountain Valley Pipeline venture has pushed back its expected completion date and says costs for the project are expected to rise.

The Roanoke Times reported Tuesday that the news comes from Equitrans Midstream Corp. It’s the lead partner in the joint venture of five energy companies.

The company has faced environmental problems and legal challenges while building the natural gas pipeline in West Virginia and Virginia. It had expected to finish construction early next year. But it’s now targeting a full in-service date “during the second half of 2021.”

The cost was estimated to be $3.7 billion when construction started. But it now stands somewhere between $5.8 billion and $6 billion.