MATTAPOISETT — The flooding at Brookside Drive during one particular storm in 2021 was something Mattapoisett Highway Surveyor Garrett Bauer had never seen before.

Approximately seven inches of rain hit the town in about three hours, Route 6 became inundated to the point of almost shutting down and there was “massive flooding” on Pine Island Road, according to Bauer. 

One house on Route 6 had water rising up to the middle of its back door, Bauer said. 

After that storm, the town began looking into the tunnel that carries a brook underneath Pine Island Road. When the culvert under Pine Island fails, flooding like the 2021 inundation can occur.

“The culvert is in bad shape,” Bauer said. “It’s old, and it’s up for replacement.”

The town received more than $40,000 from the state for the first step in replacing the failing, undersized culvert, announced Aug. 29. 

Bauer said the Pine Island culvert is “tight” and becomes clogged with sticks, leaves and other material. When the tunnel is clogged, it also blocks the passage of wildlife through it and the brook, like terrapin turtles or crawfish. 

Some of the structure’s rock support walls have also collapsed into the middle of the culvert, and after the 2021 rainstorm, there was even “half of a door” stuck, according to Bauer.

“We were crawling up the thing trying to get the debris out, and there’s no way any wildlife is going through there because it’s so narrow,” he said.

The stream carried under Pine Island Road goes to Mattapoisett Harbor. Before Pine Island, it stretches across Route 6, curving west adjacent to Brookside Drive. During a major storm event, were that area to become flooded, and residents had to seek refuge at Old Rochester Regional High School — the town’s emergency shelter — the detour would be significant. 

“If Route 6 is closed right there, people can’t get by Pine Island, can’t get by Route 6, then they have to go around to Marion,” Bauer said. “It’s quite a long detour.”

Partly for that reason, replacing the culvert is important, according to Bauer.

The state money will be used for research to assist in determining the size of the replacement culvert, according to Town Administrator Michael Lorenco.

“We don’t want to cause any more problems downstream, but design it in a way where it can handle more flow, so we reduce the chance of flooding and increase the safe passage for wildlife,” Bauer said.