Taking about 30 inches off one end of the Head Tide Dam’s spillway would avoid taking some ledge off the Sheepscot River shoreline, a consultant said Tuesday night about one of the latest models to replace an abutment and try to improve fish passage. Another model would replace the same abutment, leave the 30-inch seam that connects it to the spillway, but lose some ledge, senior water resources engineer Michael Burke of Interfluve told an Alna committee.

The town owns the concrete dam that once powered a mill. Earlier this year, selectmen formed the new, smaller committee in place of one that worked several months with the Atlantic Salmon Federation and Interfluve. The new panel’s charge from selectmen is to explore a possible project in the area of the abutment on the Head Tide Road side of the dam.

Selectmen have said they would support no project that violates a covenant that came with the dam, calling for it to never be destroyed. Before forming the second committee, the board got a lawyer’s opinion stating that any changes that leave the dam substantially in place and functioning as a dam would not seem to break the covenant.

According to ASF Vice President of U.S. Programs Andy Goode, the spillway is about 93 feet long, including the seam. Losing the seam and connecting the new abutment’s vertical wall directly to the rest of the spillway makes more sense structurally than having that new wall next to the seam, Burke said. It would also look better, participants said about losing the seam. Burke said it has not been determined yet which model would do more for fish passage.

He and Goode told the committee they weren’t looking for decisions yet on what to propose for a project, only feedback to help Interfluve further develop the models. Everyone who commented favored losing the seam and keeping the ledge intact. Doing otherwise would seem foolish, committee member Gerry Flanagan said.

However, Flanagan wondered if the seam’s removal would pose an issue with the covenant. Participants suggested keeping both options open and Goode said he’ll get a legal opinion on the covenant question.

For more than 10 minutes after the meeting’s scheduled start time, attendees waited in the town office parking lot for the building to be unlocked. But no one with a key came; attendees also used their electronic devices to try to reach a town official, or a fire official to see if the meeting could happen in the fire station across the road.

Cathy Johnson, a member of the prior dam committee, offered the use of her home for the meeting. Attendees walked across Route 218, through a field and onto Golden Ridge Road to Johnson’s 1812 home.

Interfluve is doing its Alna work under an ASF contract that also encompasses plans to remove a dam in Whitefield. Voters in that town agreed to the dam’s removal. Goode has said any project at Head Tide Dam would cost Alna nothing.

Near the close of Tuesday’s meeting, Goode said: “I think we’re headed in the right direction here, in terms of having something that could possibly work.”

A new abutment’s vertical wall would be concrete like the dam, Goode and Burke said. Concrete, wood or another material could be considered for the platform, they said.