The Southport bridge, which spans the Townsend Gut and connects Southport to Boothbay Harbor, will be closed to marine traffic for four hours August 21.

Maine Department of Transportation found several electrical problems including issues with the gates, warning lights, navigational lights and limit switches on the swing bridge.

The bridge will be shut to only marine traffic from 8 a.m. to noon, Wednesday, Aug. 21, with an alternate date of Thursday, Aug. 22.

Cars will still be able to pass through.