Herring River Restoration Project

Sediment in various forms is an ongoing and serious threat to the multi-million-dollar Wellfleet shellfish industry. In April 2022, an article about beach nourishment reported: "sand that has been piled along 36 waterfront properties from Indian Neck to Blackfish Creek is burying their oyster grants."

In a worst-case scenario, sediment coagulates to form a lethal muck:

"Black mayonnaise," an anoxic, sulfuric sludge derived from dead marsh vegetation, is encroaching on aquaculture beds, smothering the oysters. Assistant Shellfish Constable John "Clam" Mankevetch said this week that dredging will alleviate some of the risks posed by the black mayonnaise. There has been tremendous [shellfish] mortality due to smothering because oysters can't get oxygenated water," Mankevetch said.

This quote appeared in a 2018 newspaper article.

In a more subtle scenario, silt washing into the harbor from the Herring River could smother oyster beds without forming a toxic sludge. The Herring River Restoration Project will cause both the incoming and outgoing tides to move faster and transport more sediment. Project planners have reassured shell fishermen that "sediment flow is flood-dominant." However, this generalization does not account for the fact that finer sediment – silt – will flow downstream on the outgoing tide and settle in the harbor as the flow slows upon reaching the larger body of water. Whether this phenomenon, which is governed by hydrodynamic principles, will adversely affect the shellfishing beds in the harbor is uncertain (despite reassurances from the project proponents that it will not).

An added concern is that the ebb-tide silt may carry toxic substances into the harbor. The Herring River wetlands have accumulated an array of toxic chemicals over the past 110 years, which is a major reason for the Herring River Restoration Project. The project's plan for dealing with this problem is to dilute the toxic chemicals with restored tidal flow and wash them downstream into Wellfleet Harbor. Pollutants will not be removed from the environment – they will simply be redistributed. (Dredging would remove them.)

Whether silt or toxic chemicals washed into Wellfleet Harbor will harm the shellfish beds is unknown. There is no plan to compensate owners of the shellfish beds if they sustain financial loss because of the project.

The town of Wellfleet will be legally responsible for harm caused by the project, according to legal counsel. During early planning for the project, the chair of the Herring River Technical Committee recognized the project's risk to shellfishing and Wellfleet taxpayers in a set of notes that were published in May 2006:

"When will a fund be established to mitigate any damage to private property owners, businesses and shell fishermen?"
"How will the costs of restoration affect the tax rate?"

Source of Rhone River image: Sediment Transport and Deposition

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Herring River Restoration Project

Oysters & Silt