A bulkhead on the east side of the Chappaquiddick Dike Bridge needs to be replaced and initial cost estimates peg the project at $4.3 million, according to a new report.

Residents alerted Edgartown and The Trustees of Reservations about issues with the bulkhead earlier this year, prompting the town to further investigate the crossing. An engineering firm hired by the town to look into the damage found the wooden bulkhead on the eastern side of the bridge is showing significant decay, raising concerns about its structural integrity.

The town has attempted to bolster the bulkhead by putting in plywood supports, but the firm Tighe & Bond says it is clear the bulkhead will need to be replaced.

An SUV rolls onto the bridge this week. — Ray Ewing

A “conservative” replacement estimate is $4.35 million, according to the engineer’s report presented to the Edgartown select board Monday. The bulk of the costs would be for construction, amounting to $3.6 million.

Who would pay for these repairs isn’t clear, but Edgartown town administrator James Hagerty called the price tag “shocking” at Monday’s select board meeting.

“Who’s going to pay for that?” he said. “Process-wise, I don’t think the town can use taxpayer money to pay for private property.”

The bridge is jointly owned by the Trustees and the town, but the deteriorating bulkhead is on the Trustees side of the property, according to Mr. Hagerty.

In a Cape Pogue district of critical planning concern meeting in March, the Dike Bridge’s condition was raised. At that meeting, officials with the Trustees said ownership of the property is complex and the Trustees was doing its due diligence before taking any major actions.

“The issue is not just who owns it,” said Trustees attorney Dylan Sanders. “Ownership of the bulkhead is separate from maintenance responsibility.”

In a statement to the Gazette this week, a Trustees spokesperson said the orgnaization is continuing to work with the town to understand the responsibilities the Trustees may have for maintaining the bulkhead.

The town is hoping to get ahead on the repairs before the fall and Mr. Hagerty talked about drafting a letter that would call on the Trustees to put a replacement plan in place.

The select board took no action on the bridge Monday, but member Michael Donaroma was floored by the cost, saying $4.3 million was “crazy.”