Clearing of vegetation along the Herring River in Wellfleet is set to begin by November as part of a restoration project to bring more salt water into the river ecosystem.
The biggest element of the project is the removal of the Chequessett Neck Road Dike, which has blocked tidal inflow since 1909.
Starting within a few weeks, members of AmeriCorps and volunteers from the Friends of the Cape Cod National Seashore will remove brush and small trees, providing access to berms of sediment, which also need to be removed, said Geoffrey Sanders, chief of natural resource management and science at the Cape Cod National Seashore.
“After the dike was constructed, a lot of that sediment they pulled from the river channel, they dumped on the side of the river, creating berms,” he said. “Those berms are going to impact the flow of saltwater once the dike is replaced.”
The dike has a narrow opening for the Herring River to flow out, but allows no significant water in. As a result, the area inside the dike has changed from a salt marsh to a fresh-water environment, he said.
He said work is scheduled to begin this winter on a new water-control structure to replace the dike. It will allow vastly more tidal flow, but still provide human control of water levels.
“We have an adaptive management plan in place that will help us understand how best to reintroduce saltwater and convert the system back to productive salt marsh,” he said.
Goals of the project include restoring habitat and fisheries and regaining other environmental benefits of a salt marsh.
“There's a lot of positives to this,” Sanders said. “Restoring habitat for improving fisheries, oyster habitat, shellfish habitat. Salt marshes are also much more productive at sequestering — storing — atmospheric carbon.”
Supporters of restoring the salt marsh have been working on this project for decades.
In the early 1900s, the dike was intended to lower water levels on the land to make more space for pasture and crops, and to control mosquitoes.
But mosquitoes should actually be reduced by the reintroduction of tidal flow, because the flushing of water, and lower water at low tide, will reduce mosquito breeding, according to the National Park Service.