A group of residents in Almonte, Ont., are worried a plan to expand an electrical power dam in the village west of Ottawa would continue to cause harm to a sensitive wetland on the Mississippi River.

The newly formed Mississippi Mills Riverkeepers Association says close to 3,000 acres of red maple in the Appleton Wetland have been dying because several years ago the previous owners of a local energy plant increased the height of the dam in Almonte, flooding the wetlands.

Mike O'Malley said the canopy of trees in the wetland has been greatly reduced. (CBC)

Mike O'Malley said when he first moved to the town in the mid-1990s the swampy, maple forest was lush and green.

"More than half of that wetland has been seriously altered by fluctuating water levels and the tree canopy is dead, dying or gone," said O'Malley.

Now they worry the plans of the current owner, Enerdu Systems, to expand the plant to increase the production capacity of the plant from 300 Kilowatt (KW) to 1 megawatt (MW) will do more harm to the wetland.

Energy return not up to par

Association member Brian Young said the group is also concerned the dam could have other negative community and environmental impacts. He said the energy return promised would not be worth it.

"If I thought this was green energy, I'd support it. There's more damage going to occur from this and very, very little positive return," said Young.

Enerdu project manager Ron Campbell said he believes the Ministry of Natural Resources (MNR) should look into what is happening in the wetlands but said he does not believe the dam is the cause.

"That dam's been in place for a very long time. Whatever situation that's taking place in Appleton swamp is something other than just the water levels," said Campbell.

MNR said Enerdu is operating within the rules, adding it had a forestry biologist look into the dead trees but had no answers as to what was causing them to die.