Fishway Planned For Bank Street To Grass Pond

 HARWICH - The town is planning major improvements to the Cold Brook culvert, which runs under Bank Street, including altering the fishway leading into Grass Pond. Herring have had a difficult time reaching spawning headwaters in the pond in recent years. 

 The town has obtained a federal grant through the USDA Natural Resources Conservation Service and the Cape Cod Conservation District to fund the design and permitting for the improvements.

Conservation Administrator Amy Usowski said that there was concern that the $206,000 grant would not be awarded, but while there was a short delay, she said the Cape Cod Conservation District did secure the grant. 

 The town is seeking proposals to design and replace the culvert under the road and develop a fish passage structure to connect upper Cold Brook with Grass Pond.

 Conditions between the two waterways impair the ability of river herring and American eels to migrate. The Harwich Conservation Trust’s eco-restoration of the Cold Brook channel in the Robert F. Smith Cold Brook Preserve has improved migratory access to the headwaters pond.

The metal pipe culvert under Bank Street is old and corroding, and the fish passage needs to be adjusted to allow herring to access the headwaters, said Usowski.

Brad Chase, the chief diadromous fisheries leader for the state Division of Marine Fisheries (DMF) and a former chair of the town’s conservation commission, has been pushing for improvements to the brook to allow diadromous fish to access Grass Pond. 

Chase said a flume was placed in the brook to control water flow for the cranberry bogs in the 1930s, and the bog owner managed the flow to allow herring to access the pond. Chase said his father told him there was an active run there in the 1950s, but conditions changed over time, prohibiting herring from reaching the spawning headwaters.

An “eelavator” was installed by DMF in 2008 to provide headwater access for American eels. Annual counts indicated more than 65,000 eels passed through a counter between 2008 and 2015. The counter was removed when access to electricity was lost.

“Considering the average annual count, the ramp has likely passed well over 100,000 eels to date,” Chase wrote in an email, “with many of those early eels maturing and on their way to the Sagasso Sea to contribute to the spawning stock.”  

The American eel has a catadromous lifestyle; in essence, it migrates from freshwater ponds to the depths of the Sagasso Sea to spawn. Its larvae drift on currents back to the Atlantic coastline, becoming elvers (young eels), and eventually much-valued glass eels. The eels live in freshwater bodies, and when they mature they return to the Sagasso Sea to spawn and die.

Chase said the eco-restoration conducted by the Harwich Conservation Trust seems to have improved the downstream movement of the eels.

“We are seeing eels there this year, more than we’ve ever seen before,” Chase said. “I’m seeing them in the pools, downstream and at the ramp. It could be restoration downstream is helping them to move upstream. It’s a good eel system and it should be good for river herring.” 

Chase said Fuss and O’Neill, an environmental engineering firm, worked on assessing conditions and providing a “nature-like” fishway from Bank Street to Grass Pond. There would be a series of weir pools from Bank Street to the pond that will step the brook up to the pond, he said. In his role as diadromous fisheries leader on the state level, Chase said he helped Fuss and O’Neill in the review process and development of the fishway concept. There would be a lot of stone used in the shaping of the weirs, he said.

“It would look a lot like Stony Brook in Brewster,” Chase added.

Usowski said the grant is available through 2026. She said the design and permitting should be completed within the year so that next spring the town can pursue construction funding.  

Proposals must be submitted to the town by Tuesday, May 27 at 2 p.m.