A federal appeals court is allowing construction to proceed on a 53-mile stretch that’s a critical part of a $1 billion utility corridor aimed at bringing Canadian hydropower to the New England grid.

The 1st U.S. Circuit Court of Appeals on Thursday rejected a request for a delay while three conservation groups sue for a more strenuous environmental review.

Construction was on hold until the appeals court ruled. A federal judge previously rejected the request for a delay, as well.