The case of the mystery seawall at Sprague’s Cove has been solved.

At Tuesday night’s Selectmen meeting Town Administrator Paul Dawson told the board that after a little bit of investigating he found that the wall was built in 2013 by the Department of Public Works.

It was built as part of a project by the Conservation Commission to stop the erosion of the earthen dikes in the cove.

Dawson said that the project had taken a couple months to complete, so people in town were aware of it being built at the time.

He also stressed that there was no malintent by the DPW and that they believed they were operating within the town’s maintenance plan for the cove.

“There was no understanding that they were within the Army Corps of Engineers jurisdiction,” he said. “At a yearly meeting it was decided what maintenance needed to be done and then it was done by the DPW at that time.”

The town will negotiate with the Army Corps of Engineers about the more then $33,000 mitigation cost it owes using the original 1991 plans.