An illustration from a presentation to the Harpswell Board of Selectmen shows a traditional mooring (left) next to a conservation mooring.
The traditional ball-and-chain moorings in use throughout Maine damage ecologically important eelgrass beds. In Harpswell, an effort is underway to demonstrate how the replacement of these moorings with “conservation” moorings can allow eelgrass to regrow.
The town hopes to obtain a $212,239 grant from the Maine Natural Resource Conservation Program to replace 20 traditional moorings in Curtis Cove, Dipper Cove and Stover’s Cove with conservation moorings. The board of selectmen approved the grant application Sept. 2.
Conservation moorings have proven successful in eelgrass restoration efforts elsewhere in New England, but “very little data exists from Maine waters,” according to the application.
Scientists have identified block-and-chain moorings “as one of the significant stressors to eelgrass in Casco Bay,” according to the application. As the chain drags on the bottom, it kills eelgrass and creates a “mooring scar” within the eelgrass bed. Data from Portland Harbor shows that these barren areas measure an average of 437 square feet.
Conservation moorings use a helical anchor and tether system to eliminate the bottom chain.
Projects like Harpswell’s “have a high likelihood of success because the habitat conditions that support eelgrass already exist” and eelgrass often regrows in scar areas, according to the town’s grant application.
Of Harpswell’s approximately 2,400 moorings, all or nearly all are traditional moorings, according to Harbor Master Paul Plummer. The town “might have a couple helicals,” he said, but they are rare in Maine.
Harpswell no longer permits new moorings in eelgrass beds and, as part of the project, plans to propose new regulations that would prohibit the conversion of a conservation mooring back to a traditional mooring.
Eelgrass provides habitat for juvenile fish and sequesters carbon. The mighty plant also filters runoff and protects the shoreline from erosion, according to the National Oceanic and Atmospheric Administration.
The town selected Curtis Cove, Dipper Cove and Stover’s Cove for the project because they each have abundant eelgrass, along with mooring scars.
Curtis Cove and Stover’s Cove are on opposite sides of Harpswell Neck, on the southern end of the peninsula. Dipper Cove is on the northwest side of Orr’s Island.
The town is partnering on the project with Stantec Consulting Services Inc., which has a dive team with experience in eelgrass monitoring and restoration. Randlett Marine Services LLC would install the moorings, then conduct annual inspections and maintenance.
The Stantec dive team would measure the scars at each potential location. The harbor master and Stantec would then pick 20 moorings from among the 84 in the three coves, prioritizing those with the largest scars and working with mooring holders. Installation of the conservation moorings would take place over a week in spring 2022.
Over the next five years, the Stantec divers would measure the scars once a year and document the eelgrass’s return.
Of the $212,239 price tag, more than half would go toward the purchase and installation of the conservation moorings, with much of the rest for annual inspections and maintenance, as well as annual surveys by the dive team.
The town hopes the project can serve as a model for other Maine towns.
“A successful, well-documented eelgrass restoration project will have much broader benefits to eelgrass in Maine than just the mooring scar areas restored,” the application states.