YARMOUTH, Maine — Discussions about removing the Bridge Street dam are on the horizon now that the dredging of the Royal River is complete.

Town Manager Nat Tupper said he expects to discuss the fate of the dam with the Town Council after April 1, as decided by councilors last year.

Tupper has been meeting with the Bridge Street Dam Steering Committee since September, discussing different aspects of the dam, and he said he will report to the Town Council when the committee’s work is done.

Tupper said his role is not to make a suggestion to councilors about whether the dam should be removed. He said he will help councilors determine what tests should be done to find out what material is behind the dam.

Councilors will vote on whether to remove the dam after the findings come back.

He said the steering committee has been working with the Maine Department of Environmental Protection and the U.S. Army Corps of Engineers to find out what chemicals the town should be testing for in the sediment that has built up behind the dam.

“The question we need to ask is what is the nature of the material behind the dam, and how will it affect what’s downstream?” Tupper said.

He said there are 5,000 cubic yards of material behind the dam.

People against the removal of the dam, including marina owners, are concerned about the volume of sediment, and the chemicals that may be in it, being released down into the harbor.

“There’s a lot of risk that’s involved in taking out the dam,” Steve Arnold, owner of Yarmouth Boat Yard, said. “There’s a lot of sediment that’s been there 100 years. Our ability to operate as marinas could be affected.”

Councilor David Craig, an advocate for the dam’s removal, said 5,000 cubic yards is a small amount of sediment when looking at how much material accumulates between dredges.

“It represents only a few months of a 10-year dredge,” Craig said. “It’s insignificant.”

Rivers are supposed to be dredged every 10 years, but before the dredging of the Royal River was completed in January, it had been 18 years since the job had last been done. There were 103,000 cubic yards of material dredged in the project that just ended.

But Arnold maintained that 5,000 cubic yards of material is a large amount to release all at once.

“Immediately it comes down, and we just dredged,” he said. “[Marina owners] look at it as potentially crippling us.”

Craig said releasing that much material at once won’t make a difference, especially because the material there is constantly being replaced by new sediment as old sediment gets pushed over the dam.

“It’s a moving system of sediment,” he said. “The chemicals that are there are going to come down anyway.”

Marina owners said too much is still unknown to make that kind of assumption. They said tests and studies need to be done before councilors can make an informed decision.

“The life of our business hangs in the balance,” Deborah Delp, president of Yankee Marina, said. “[Removal is] not the best choice for the Yarmouth community.”

The primary reason advocates support the dam’s removal is to allow fish to more easily swim upstream to spawn. Marina owners said that isn’t a strong enough reason.

“To remove the dam, we potentially help fish, but we lose so much,” Delp said.

Bruce Soule, a Yarmouth resident and an engineer, said advocates for the dam’s removal don’t know for sure that fish would come up the Royal River if the dam is removed. He said people have said salmon would come to the area, but that this wouldn’t be possible.

“There are no salmon alive who know that this is home,” Soule said. “You can’t use salmon as an argument.”

Soule also said it would cost the town a lot of money to stock the river with salmon. Delp said she would like to see the town put in a new fish ladder to help fish get over the dam.

Craig said the dam “does next to nothing” and he’d like to see it removed so fish can come through.

“[The dam] is doing nothing more at this point than preventing fish passage,” he said.

He also said removing the dam would be good for the environment.

“Just having all the rivers going into Casco Bay restored to their natural state is better for the bay,” he said.

Delp said if the council does decide the dam should be removed, she’d like to see the decision go to a voter referendum.

Tupper said the marina owners probably don’t have to worry too much, because he doesn’t sense much passion on the council for removing the dam.

Discussion of the dam is not on the council’s agenda. According to minutes from the steering committee’s Feb. 17 meeting, members do not see April 1 as a deadline for reporting to the council.