State environmental regulators gave their blessing to the Long Island Bridge as Boston and Quincy gear up for a protracted legal fight over the contentious project.

The Massachusetts Environmental Policy Act Office announced yesterday that it was satisfied with Boston’s proposal, moving the $80 million project to reconstruct the bridge along to other state permitting bodies.

But there remain deep troubled waters under the bridge between the two neighboring cities. The bridge that would connect Quincy’s Squantum peninsula neighborhood to Boston’s Long Island is deeply unpopular in the smaller city. Boston Mayor Martin J. Walsh, on the other hand, deems the bridge as vitally important to the ongoing addiction crisis as he plans a large drug-treatment center on the island

The project hit a hurdle earlier this month when Quincy’s Conservation Commission voted it down on environmental grounds. A Walsh spokeswoman yesterday said Boston is preparing to appeal that decision to the state.

The bridge is highly unpopular in Quincy, where residents fear increased traffic through the narrow roads of Squantum and North Quincy. A bridge carried traffic between Quincy and Long Island, where a hospital was located for six decades, before the span came down in 2014 because of structural concerns.

The old bridge’s pylons remain, and Boston intends to repair them and build the new bridge on them in the coming years. But Quincy, which is advocating for a ferry service instead of the bridge, claims the pylons are structurally unsound and would require much more work that would disturb the ocean floor.

Quincy Mayor Thomas Koch is seeking permission from the City Council to spend $250,000 on lawyers and engineers to fight the bridge in court, Koch Chief of Staff Christopher Walker told the Herald yesterday. Walker said Quincy is planning a challenge to the Boston Conservation Commission’s approval of the project in May, and is weighing a challenge to yesterday’s MEPA decision.

Walker said both mayors speak regularly, and both sides appear to remain entrenched.

“It doesn’t seem like there’s going to be a change in anyone’s position here or there,” Walker said.