Harwich Commission Examines Cold Brook Eco-Restoration Proposal

By: William F. Galvin

Topics: Groundwater protection , Wastewater treatment

Harwich town seal.

HARWICH – The town’s extensive review of the Cold Brook Eco-Restoration Project got underway with the filing of permit requests with the conservation commission. The project, a partnership between the town of Harwich and Harwich Conservation Trust, seeks eco-restoration and nitrogen mitigation of fallow cranberry bogs.

The commission received its first presentation of the project on June 15. Commission members and neighbors had a number of questions and recommendations during the review of the 75 percent design plans for the project.

Harwich Conservation Trust is the owner of the 69-acre Robert F. Smith Cold Brook Preserve along Bank Street. The proposal seeks to alter 49 acres to address the trust’s goal of conducting eco-restoration and the town‘s goal of designing a natural system to remove excess nitrogen in the Saquatucket Harbor watershed using ponds and wetlands.

Nick Nelson, a senior geomorphologist with Inter-fluve of Cambridge, said the current design for changes to the fallow bogs include realigning,4,700 linear feet of Cold Brook, creating 9.5 acres of saltmarsh, 2.2 acres of shallow ponds, 3.2 acres of deep emergent marsh, 3.7 acres of shallow marsh/shrub swamp, and 19.7 acres of shrub swamp/forested wetland/upland. 

“It will look like a bomb went off during construction,” said Nelson, who grew up in Harwich.

When the work is completed, however, there will be rapid transition as a result of native plantings, he said. There will also be transition from scrub pine conditions to a forest of Atlantic while cedar trees.

Commission member Alan Hall wanted to know what the difference is between naturalization--allowing the fallow bogs to revert to the conditions of 100 years ago – and manmade eco-restoration.

“The difference between naturalization and eco-restoration is $2 million,” responded commission member Brad Chase.

Nelson said a foot and a half of sand has been placed on top of the bogs during the past 100 years, which has impacted the hydrology. There are no wetland habitat species any longer, and “if you let it go it would become a pine forest and not a wetland,” he said. Wetland restoration is essential to nitrogen removal, he said.

Conservation Administrator Amy Usowski said the commission has to look at how the project meets the state Wetland Protection Act and the town’s wetland bylaw. This is a much bigger project than the commission usually is asked to consider, she added.

Usowski raised questions about the height and deck spacing on a proposed boardwalk the trust is proposing as part of its trails and Americans with Disability Act improvements. She said there is a need for more light to reach plants under the walkway. Nelson said the concerns would be addressed.

“Overall I’m greatly in favor of this project,” Usowski said. “A lot of work and science went into this project. Every site is different, but the idea is to bring it back to normal, wetlands.”

Chase, who is also a state division of marine fisheries senior marine fisheries biologist in charge of diadromous fisheries, had a number of questions about changes to the Cold Brook creek flow and the addition of wood logs and root placements along the edge of the brook. He said those items can collect debris and clog the flow of water.

Cold Brook is both a herring run and a passageway to headwaters for glass eels, Chase said, and he was concerned about disrupting the movement of the species.

Nelson said herring would remain in pools and then make their way up the creek. He said there will be water in the stream that will allow fish to pass. But Chase said he would like to have the scale of root and logs reduced to allow better flow. It was agreed Chase and design consultants from Inter-fluve would discuss that design aspect.       

“It’s a great project,” Chase said of the overall eco-restoration.

Commission member Wayne Coulson asked if the proponents had consulted with Cape Cod Mosquito Control about the addition of the wetlands. Nelson said Mosquito Control has been approached.

“There are mosquitoes there now and there will be after this project,” Nelson said. “To date, none of these projects have had neighbors complain about an increase in mosquitoes.”

Neighbor Allin Thompson said he was not opposed to the filling in of a small pond, which he called a “tremendous mosquito haven,” adjacent to his Hoyt Road home. But he has a private well he uses to water his lawn, and he wanted to know if the project would impact the groundwater level or allow more saltwater. 

Nelson said it is something they have been looking at given the surrounding neighbors. No change in the groundwater level is anticipated, but he said there should be no change in saltwater levels. But he added that he cannot predict what climate change might do in the future.

“If massive coastal storm water gets in there, it would take longer to get out of there now, than with these changes,” Usowski said.

Without input from the state Natural Heritage and Endangered Species Program, the commission agreed to continue the hearing to its July 6 meeting.