MACHIAS — A new temporary bridge over the Middle River in Machias will be built next year, an effort to keep traffic moving while state and local officials hammer out a long-term plan.

The current bridge dates to the Civil War era and is deteriorating, according to the Maine Department of Transportation. To shore it up, the state installed a temporary bridge late last year but has now decided to build a new $2 million bridge in 2025 designed to last 15 to 20 years.

“We understand residents and Route 1 travelers in Machias and Marshfield are frustrated with how long this project is taking and we share that frustration,” Transportation Commissioner Bruce Van Note said in a statement.

But the state says a federal requirement to conduct an environmental review means that a permanent bridge solution is years away.

What to do with the bridge — a wood and stone masonry box culvert with four hinged flappers originally designed to aid in fish passage — has been controversial for years.

In June 2022, more than 50 landowners told state transportation officials that they feared losing land if the dike system is replaced with a bridge. At the time, federal officials said they preferred a bridge because they believe the Middle River could be a place for endangered Atlantic salmon to spawn.

Another complicating factor is the presence of two landfill sites along the river that could be compromised if water flows freely, according to Marshfield Select Board Chairman Wayde Carter.

Last November, Maine transportation officials announced that they planned to rebuild rather than replace the span.

The new temporary bridge will be paid for using state funds to avoid federal permits or review, according to the agency.

“MaineDOT’s core mission is to ensure safe and reliable transportation,” Van Note said. “To achieve that in this case, we need to construct a more durable temporary bridge, pause the federal environmental review process, and work with the towns as developments unfold. That work includes a local effort to plan for resiliency.”