Habitat Restoration (Dredging) 

Dredge Survey on Dead Neck

Dredge Survey on Dead Neck

Restoring nature’s authentic landscape through dredging was part of the genesis of the inaugural mission at Three Bays Preservation, Inc. This first major initiative that blended engineering and science, launched in November 1998 in the channels of Cotuit Bay, was specially designed to restore wildlife habitat on Dead Neck Island, and repair storm damage to the sandy beaches. 

That sand had to go somewhere and Three Bays knew just the place.

The byproduct of dredging – that granular substance of rock and mineral particles – was deposited on the south shore of Dead Neck Island, then on the verge of disappearing because of relentless wave action.  Phase I was finished on January 9, 1999, after 187,000 cubic yards of sand was transferred onto Dead Neck Island.  [A cubic yard of sand, for example, weighs about 1.5 tons, or up to 3,000 pounds.] 

Dredging never was nor is a simple process, and it’s wicked expensive. It’s filthy and arduous work, but well worth the effort. Over 400 people – part and full-time residents – who live on this watershed, raised $1.5 million to cover the cost of that 1998-99 dredging project, and this serves as a reminder even today that maintaining our natural resources is a shared concern.  And because anything related to local, state and federal governments isn’t as simple as drawing a line between Points A and B, a lengthy process of permitting came into play: extensive engineering plans, for one, as well as securing a dredging contractor and the laborious trail of obtaining local, state and federal permits. But Three Bays, then a fledging organization, rose to the occasion.

The next phase of dredging came during the winter of 1999-2000 in West Bay when more than 16,000 cubic yards of sand were pumped from the channels there, bound for Dead Neck Island. As winter waned and spring set in, an additional 8,700 cubic yards were added to the Island’s sandy girth by the Barnstable County dredge.  And the work continued. More dredging in January 2001 transferred more than 15,000 cubic yards of sand in the channels of West Bay onto Dead Neck Island. Members of Three Bays privately funded the work undertaken by the Town of Barnstable, with great results. Since then, navigability of the bays has drastically improved, and so has the actual stability of the barrier beach at Dead Neck.  Transforming Dead Neck has been life changing to this ecosystem. Dredging that has removed sand and improved water circulation helps keep shellfish beds healthy, and improves the habitat for fish and indigenous plants that grow under the water sheet. 

It’s work that never seems to end. Back in 2002, Three Bays once again partnered with the Town of Barnstable to remove 9,000 cubic yards of sand from the Cotuit entrance channel. That latest round of dredging saw a new use for the sand that was removed. This time sand was added to Sampson’s Island, creating a wondrously fresh open sandy two-acre habitat for nesting coastal waterbirds. 

Protecting Dead Neck and restoring the eroded sand to its most beneficial location is important to the entire island ecosystem.

Dead Neck provides flood control and storm damage protection for the bays and northern estuary.  The fact that Dead Neck / Sampson’s Island (DNSI) shoulders the entrance channels to West Bay and Cotuit Bay has created a shallow coastal estuary that is now home to any number of species of shellfish, including commercially-grown quahogs and oysters, and native mussels and soft shell clams. Many species of finfish find shelter in this estuary, along with other sea creatures that inhabit the ocean floor known as the benthic region. This shallow coastal estuary is an ideal habitat for eelgrass (Zostera marina) that is so crucial to the sea life within the Three Bays natural systems.  But with deep regret, we have to report that all known eelgrass beds are now gone.  And today, high levels of nitrogen and other man-made pollutants threaten this special coastal estuary. 

And additional erosion along the barrier beach spells bad news for coastal shorebirds and other wildlife on DNSI, especially nesting shorebirds protected under state and federal laws such Piping Plover (Charadrius melodus,) which is listed as threatened; the Least Tern (Sternula antillarum,) listed by the Commonwealth of Massachusetts as a species of Special Concern; the Common Term (Sterna Hirundo,) also identified by the Commonwealth as a species of Special Concern.  Additionally, the American Oystercatcher (Haematopus palliatus) that nests on Dead Neck has been designated as a Species of High Concern in shorebird conservation plans for the Eastern and Gulf coasts. Willets (Tringa semipalmata) and spotted sandpipers (Actitis macularius) are also seen on DNSI.

A Historic Ecosystem

Dead Neck’s history is fascinating. At its eastern end, Dead Neck used to be part of the mainland of Cape Cod. But that changed in 1901 when a channel was dug to provide access for boats into West Bay. This decision to dig was prompted by the growing popularity of Cape Cod as a tourist destination, especially for wealthy tycoons from Boston and their big boats. Two stone jetties supplied by the Commonwealth of Massachusetts define the channel and these jetties are on state-owned land. Along with other structures to the east, these twin jetties create barriers that unfortunately halt the westward littoral drift of sand to Dead Neck. And without this littoral sand impeded by jetties, Dead Neck once again is eroding until further dredging replenishes its beaches. 

In the meantime, Three Bays has consulted with Applied Coastal Research and Engineering to study the movement of sand on DNSI.  A recent study from 2015 – the Dead Neck Beach Nourishment Monitoring and Data Analysis – reveals that around 12,000 cubic yards a year of sand are lost on barrier areas on DNSI.  And a corresponding accumulation of material in the Cotuit Bay entrance channel piles up at the west end of the Dead Neck/Sampson’s Island system, all because of the natural ways in which sediments travel on an east-to-west route along this stretch of shoreline.

Here’s what’s happening:  in recent years the accretion of a spit at the western edge of Sampson’s island, the so-called tip – has reduced the channel width on the western end of the island to 230 feet, affecting a number of factors, including navigation and public safety, shorebird habitat creation, and to a lesser degree, water quality in the south Cotuit Bay area, all because of reduced circulation of water flow.  Current plans call for dredging the tip of Sampson’s Island to improve navigation, safety and water quality. And the current application process for dredging will enable Three Bays and the Town of Barnstable to continually place more sand on DNSI to fortify its structure and continually provide new open sand areas for nesting shorebirds.

Sometimes concerns erupt seasonally, as do many considerations in nature. DNSI, identified by the National Audubon Society as an Important Bird Area (IBA,) is a leading regional ‘pre-migration fall staging area’ for both Common and often Roseate Terns (Sterna dougallii,) a species that’s designated as endangered on both state and federal lists. In fact, for your context, the entire DNSI system is a BioMAP Core Habitat, so says the Massachusetts Natural Heritage and Endangered Species Program (MNHESP.) The Program goes so far as to classify all of DNSI as a ‘priority habitat’ for rare and endangered species, mostly because of its dense population of Piping Plovers and terns that’s monitored by the Coastal Waterbird Program under the Massachusetts Audubon Society.

As of 2015, the tides and currents have moved previously dredged sand from east to west on DNSI.  We’re seeing an issue with a jetty that protects West Bay and now lies in danger of being breached, and it’s deteriorating and desperately needs repair. But what we’re most concerned about is the imminent loss of habitat for nesting shorebirds all over DNSI.  These factors have led Three Bays to seek additional permits to conduct more dredging to procure sand and rebuild the island and restore the nesting habitats. It’s like Groundhog Day, but in a maritime environment played out every fifteen years.

Fine-tuning these landscapes that meet up with the marine environment is a continual process for us at Three Bays. Here we are in 2016, and though we’ve accomplished quite a lot in our twenty years of existence, we remain at the mercy of nature. And it shows.  Already the extensive dredging work done in the late 1990’s and 2000’s has been rendered nearly useless as wildlife habitat because of the unending shifting movement of sand.

 


 

Please see the link below for the reports on this project;