PROVINCETOWN — An on-again, off-again effort to install a gap in the Long Point Dike, more commonly called the West End breakwater, took a small step forward last week at a public meeting organized by town officials and the Army Corps of Engineers to gather public input on the project.
Larry Oliver of the Army Corps presented the results of a preliminary model that suggested a single breach near the midpoint of the breakwater would be sufficient to allow larger fish to access the 385-acre West End salt marsh, which is fully enclosed by barrier dunes and the permeable breakwater.
According to the model, that single breach would not meaningfully increase the speed at which water already moves through the lowest point on the breakwater — although Oliver said that more sophisticated measurement and modeling of currents would be the next step in the project. The analysis suggested that installing three separate gaps would not be more effective or safer for swimmers than just one, Oliver said.
About 25 people attended the meeting, and many asked questions, including how the breach would affect recreational shellfishing flats and whether it would help protect the salt marsh from the invasive purple marsh crabs that have denuded acres of spartina grass since 2016.
The project is not aimed directly at the marsh crab problem, Oliver and Provincetown Community Development Director Tim Famulare said.
“We didn’t justify this project based on the marsh crab,” said Oliver. “We just want to increase connectivity because we have 400 acres of marsh that aren’t available as habitat. In general, even if it weren’t the marsh crabs, things get out of balance when you don’t have top predators there.”
Famulare said that other salt marshes on Cape Cod Bay that are not confined by dikes are also being consumed by purple marsh crabs, so it isn’t clear that allowing predator fish species to enter the West End marsh through a new breach would be sufficient to keep the crabs in check.
Geoff Sanders, the Cape Cod National Seashore’s chief of natural resource management, who also attended the meeting, agreed. “Providing additional flow through the breakwater would be ecologically beneficial to the marsh system in general,” he said. “That does not mean it’s going to solve your purple marsh crab problem.”
Experiments in the West End marsh have shown that adding sand to exposed spartina roots and laying down nets to block the marsh crab have been effective on a small scale, Sanders said. These solutions can be difficult to apply broadly because of funding and permitting issues, but the Park Service hopes to move toward larger-scale interventions, Sanders added.
Project Origins
The idea of installing a breach in the breakwater was first raised in May 2006 in a pair of letters to the Provincetown Select Board from then-Director Peter Borelli of the Center for Coastal Studies and then-Supt. George Price of the Cape Cod National Seashore.
Price’s letter cited the ecological benefit of installing a breach, both for the marsh itself and for the recreational fishery in Provincetown Harbor and Cape Cod Bay, which would benefit from the “nursery function of the salt marsh,” Price wrote.
The project was put on hold by the Army Corps in 2006 and again in 2010 because of lack of funding for ecological restoration projects. When funding became available in 2016, town voters had become skeptical of the project. Not much was known about the effect of a breach on the town’s commercial aquaculture grants or the recreational shellfishing flats that lie on both sides of the breakwater, and the Army Corps did not prepare answers to those questions in its 2016 proposal.
A $51,000 funding authorization for further study of a breach was indefinitely postponed by town meeting voters in 2017.
The purple marsh crab had been expanding northwards from its mid-Atlantic habitat into Nantucket Sound and Cape Cod Bay, however, and around the time of that vote, the spartina grass in the West End marsh began to die back and wash away.
There are now large areas in the center and north of the marsh that have been entirely denuded of both grasses and the carbon-rich peat that supported them. Provincetown’s conservation commission began discussing a breach again in 2021.
Public Outreach
The Sept. 25 meeting was partly designed for the Army Corps to learn about public concerns with the project, including its effects on shellfishing and aquaculture.
Several people wanted to know if a breach could result in a deep channel through the flats that could not be traversed at low tide.
“It’s my opinion that a study on sedimentation is an absolute,” said Provincetown resident and oyster farmer David Flattery. “If there’s more erosion than we think is going to happen, there would be no turning back from big erosion on the tidal flats.”
The Army Corps sometimes installs a “rock apron” for a hundred or so feet on either side of dike openings to protect the sea floor from swift currents, Oliver told the Independent after the meeting.
“We won’t have a prediction of what the channel that forms around the opening will look like until we perform additional modeling,” Oliver said. “It’s likely it will need rock protection within and to some distance beyond the opening.”
Other residents asked about sharks and marine mammals.
“One concern is that opening up to large fish will also allow large sharks,” said harbor committee chair Michela Murphy. “I’m not saying people should come before the environment, but it’s one of the last places that people can swim freely here.”
Murphy also asked whether dolphins could strand inside the breakwater, given that “we just had one of the largest strandings in history in Wellfleet.”
Oliver said that, as a biologist, he wasn’t concerned about fish becoming stranded but said he would consult marine mammal experts about the potential for dolphin strandings.
Town meeting voters approved $120,000 for studies in 2023, and the Army Corps will match that amount, so there is already funding in place for a more detailed analysis of tidal currents through a potential breach, Oliver said.
Those data would likely be presented in the late winter or early spring, Oliver told the Independent.
Design, permitting, and construction would cost about $2 million and would have to be authorized by voters at a future town meeting, since the town would pay one-quarter of that cost while the Army Corps pays three-quarters.
Final plans and permitting take more than a year, Oliver said, so the earliest a breach could actually be installed “if things go reasonably well” is 2027.
