One of the last remaining swing bridges in Maine is set for major repairs next year — but what makes it different from thousands of other spans in Maine will not change.

The bridge that connects Boothbay Harbor to Southport Island, built in 1939, needs work on its deck, supporting structure, and electrical system, said Jason Stetson, a bridge project manager at the Maine Department of Transportation.

The bridge is eligible to be listed as historic because it’s one of the last remaining swing bridges in Maine. The bridge is staffed and opened manually when boats taller than 10 feet need to pass through Townsend Gut. It opens by swinging the middle section to the side to let boats pass through.

“There’s very few that are like this one left in Maine,” Stetson said, saying that the repairs will improve the bridge without changing how it operates.

As of Thursday morning, Stetson has received five written comments on the project, with most of them in support. Some have questioned whether summer lane closures will be necessary. Stetson said there will be a single-lane closure on the two-lane bridge in summer because part of the project involves concrete, which needs to be used in warmer weather.

Other work will take place in the fall and winter, in part to accommodate environmental concerns prompted by the presence of Atlantic salmon and Atlantic sturgeon.

The $13 million project will be paid for with 80% federal funds and the rest covered by the state. Following the virtual public meeting in June, the state set aside 14 days for a comment period, which ends Friday.

About 3,250 vehicles travel the bridge each day, with numbers swelling in the summer to accommodate those with summer homes on the island. The 368-foot-long span is scheduled to undergo construction in early-to-mid 2023 with completion in 2025, Stetson said in a video posted on the state transportation website.

To watch the on-demand video explaining the project or to comment on it, visit the state’s virtual public involvement page.