DEXTER — A 200-year-old stone canal next to a 19th-century grist mill helped save the mill, which houses a museum and the town historical society, from being washed away when the East Branch of the Sebasticook River ate away roads downtown last week.

“The original stone construction on the canal really helped save our building by diverting water away from the foundation. It’s still there doing it’s job,” said Rick Whitney, director of the Dexter Historical Society Grist Mill Museum.

The entrance to the museum has been blocked off since elevated water levels in East Branch, which flows through downtown, washed out a large culvert and the road above it and left part of the mill hanging over the river.

The flooding also destroyed a culvert and section of Lincoln Street, closing the Town Office and Main Street businesses last Wednesday during the peak of the high water. None of the busineses aside from the Town Office, which has water in its basement, was damanged.

Officials say it’s still too early to tell what the cost of repairing the roads will be, which experienced the bulk of the storm damage.

“It’s just too soon,” said Town Manager Shelley Watson. “No one has been in the office because of the long weekend, and we’re still waiting to figure out the estimated costs from the different departments.”

The museum, which is town property, has flood insurance, but there was no water damage inside, something that Whitney said he also credits to the old stone canal, which diverts water from the river away from the building’s foundation.

Water levels reached at least 10.3 feet last week on the East Branch, more than a foot above the river’s 9-foot flood level, according to the National Weather Service. Precise readings of the flood levels could not be calculated because of federal cutbacks that led to the removal of a river gauge.

“We’re not in any danger at this point, to a lot of people’s relief,” Whitney said. “We were worried when they evacuated downtown that we might have to move everything out.”

The rushing river removed posts that supported an addition to the original building, part of which dates to the 1830s and was remodeled in the 1850s, he said.

There have been problems on the embankment before, but the canal has helped divert water from the building’s foundation.

“We’re lucky. It looks worse than it is, but the main building is strong and nothing has changed there,” Whitney said.

He said the addition, which houses the museum offices, will need additional supports put in when water level recedes; but the museum is waiting for the town to asses what will be done there as well as on the road in front of the museum. The culvert under that road — which dates to the 1970s — might not have been strong enough to sustain the elevated water flow, Watson said.

The town will meet with the Eastern Maine Development Corp. later this week and is in the process of filing paperwork with the state to see if it qualifies for any aid, she said.

Residents on Water Street, which runs parallel to the river and intersects it at some points, said that although water levels were high, there was no reported damage to any homes.

“It’s coming down slowly and surely. We were told we may have to be evacuated, but in the end the water levels weren’t more than a cinderblock high,” said Robert Champaign, pointing to a neighbor’s mobile home where he estimates water was flowing up to the base of the house last week.

Florence Turek, another Water Street resident, said there was no damage to her home and that she is more concerned about the historical society building.

“It’s crazy. Everyone is going under the police tape to see what it looks like. Everybody wants to get a look, because it’s just hanging on a ledge,” she said.

The museum is open from late May through September, and Whitney said the storm shouldn’t affect its opening this year.

“I think in a couple of weeks the water will slow down enough that we can get another post under that corner. Of course, it might depend on funding, and we’re waiting to see what that might be,” he said.

Rachel Ohm — 612-2368 [email protected]