NEWRY – Fixing two of three erosion sites on the Bear River should be relatively easy, but the third could require grants and state aid.

That was the consensus last week of the Bear River Watershed Committee, a group of landowners and municipal officials seeking to identify and address erosion problems in the watershed.

“Rivers are pretty touchy things,” said Jeff Stern, a committee member and project consultant. A naturally meandering river will maintain its width and depth, but rivers are very susceptible to change, he said.

According to a Dec. 1 report from river expert John Field of Field Geology Services in Farmington, such a change occurred before 1941 when the river channel was straightened.

“When a river changes its profile dimensions, more than natural migration is happening. You get a river that’s kind of out of whack,” he said.

Straightening the channel, Field stated, caused a hard bend to be created downstream near the river’s confluence with the Androscoggin River.

That bend is causing erosion along a high bank of glacial deposits that may be supplying considerable amounts of sediment to gravel bars downstream, he said. Field doesn’t believe the erosion is enough for Newry to consider making significant investments to achieve long- term riverbank stability.

Committee members and Stern disagreed.

Considering options

Stern said that committee members believe the riverbank erosion, which is near Route 26, is occurring in chunks of 10 feet or more annually with each significant storm.

Field said the eroding bank comes within 210 feet of Route 26.

“The likelihood that the bank will recede 210 feet due to erosion, and threaten the road, seems remote during a 10- to 50-year period,” he said.

Furthermore, he added, the river channel could potentially shift away from the current bank and back to the south before the road is seriously threatened.

He outlined several options to manage erosion at the bank.

The offending culprit is a large gravel bar located across the river from the eroding bank.

As the gravel bar grows during large storms, it diverts flow into the opposite bank, Field said. Additionally, another growing gravel bar just upstream has caused the river to abandon its former channel.

One option is to remove the first offending gravel bar, but that would increase the size of the channel and decrease the river’s ability to carry sediment, Field said.

But, due to upstream problems, this would need to be redone with each major storm, Stern said.

Costs vary

Realigning the upstream channel would address the root cause of the erosion problem, Field said, but it would cost more than $50,000 and spawn unintended consequences.

With both fixes, acquiring the necessary environmental permits would also be difficult.

Stern said the best thing would be to install rock deflectors in the river and put riprap on the eroding bank.

“It will take a combination of approaches. Deflectors – rocks and/or logs stuck out from the bank into the river – work really well,” Stern said.

The deflector project would cost more than $25,000, and could potentially have downstream effects. “But they’re good for creating fishery habitat on the downstream side,” he said.

Stern is to complete a final report on the river’s problems and fixes by March 1, to be used at the town meeting.