The Changing Shape of Popponesset Beach, Mashpee
Editor’s note: This is the 7th in a series of articles covering the region’s dramatically changing coastline. Click here to see all of the articles.
Located in southeastern Mashpee, Popponesset is a small, quiet and scenic village with a population of just 220, according to the most recent U.S. Census. The village is situated along Popponesset Bay, which is fed by the Mashpee and Santuit rivers, which lead out to Nantucket Sound through a channel around the Popponesset Spit, a lengthy yet narrow extension of Popponesset Beach that doubles as a popular summer attraction and a barrier between ocean and bay.
The Popponesset Spit has been in a state of flux since at least the mid-1800s. According to a 1982 report from the Woods Hole Oceanographic Institute, from 1844 to 1954 records show that the spit grew to nearly 1.75 miles in length with a width across of 260 feet. In Arthur Strahler’s book A Geologist’s View of Cape Cod (1966), a map of the area shows the spit extending a good distance past the opening to Popponesset Bay—and seemingly headed for Cotuit.
Beginning in 1954, the spit was split in two following a series of three hurricanes: Carol, Edna, and Hazel. The resulting channel and its tides caused the eastern portion to eventually be absorbed into the Cotuit shore, while helping to facilitate the erosion of the western end into a shorter beach spit. Today, the spit extends just under three quarters of a mile from Popponesset Beach, with the tip bending in toward the bay at a sharp angle; at its widest, the spit’s width is just 155 feet—or one half the length of a football field—across.
Andrew McManus, Mashpee’s conservation agent, commented on efforts underway to slow the erosion of the spit. “There are currently three ongoing dredge permits in Mashpee,” McManus states, “all of which take place in Popponesset Bay. The dredging helps to keep navigation channels open for boats coming in and out of Popponesset Bay into Vineyard Sound. The dredge spoils are deposited onto the Popponesset Spit annually to help re-nourish, fortify and protect the spit from storm damage and subsequent erosion.”
Michael Oleksak, president of Save Popponesset Bay, an organization of local volunteers whose mission is to preserve the spit and keep the surrounding waterways safe and navigable, explains why the future of this barrier beach is so important. “Protection of the spit is essential as it provides protection to a number of homes behind it on Popponesset Island and other coastal areas of New Seabury from storm surges,” Oleksak says. “The spit is also essential habitat for a variety of shorebirds, including piping plovers, roseate, common and least terns.”
Oleksak describes some of the efforts the organization has undertaken. “Save Popponesset Bay, which took ownership of the western two-thirds of the spit in 2002 (with the eastern one-third owned by Mass Audubon), has partnered with the Town of Mashpee and allowed the dredge material to be placed on low points of the spit.
In recent years, the spit has endured extensive damage and erosion. During Hurricane Sandy in October of 2012 the spit was breached in several places by powerful tides; in Winter Storm Juno in January of 2015 work that had been recently completed to strengthen the spit—the planting of beach grasses and the adding of sand to the dunes—was washed away by the tide.
After Juno, Save Popponesset Bay partnered with the coastal engineering firm, Woods Hole Group, and devised a plan to strengthen the spit with additional sand. “We have since trucked in over 15,000 cubic yards of sand and have already transformed the spit with a significant dune now extending down to [Mass Audubon’s section],” Oleksak says. The organization has also planted dune grasses in hopes they will further strengthen the dunes, and installed signs and fencing to discourage visitors from walking on the dunes.
On average the dune on the spit stands one to three feet tall, with its highest point—about 800 feet out—measuring just over six feet.
Over the years attempts have been made by individual homeowners in the area to protect their property by installing seawalls or breakwaters to curb erosion. According to McManus, this practice has actually proven detrimental to the natural coastal erosion process. “By armoring an eroding coastal bank, you take away the sediment source that would eventually nourish other down drift coastal areas,” McManus says. “While these seawalls and revetments are effective in protecting property from storm damage, they also transfer wave energy to the next available area of coastline that’s not armored, increasing and concentrating the erosion forces of waves into those areas and amplifying the damage.” Today the Massachusetts Department of Environmental Protection prohibits the practice, and only those homes built in the area before August 1978 are allowed to fortify their shoreline; they’re grandfathered in.
Where the seawalls have been permitted, the property owners are generally required to provide an amount of annual “beach nourishment” (a.k.a. sand) that equates to an amount that would be expected to erode from the shore were it unarmored. Though great effort and expense has already been expended, McManus views the construction of seawalls as a temporary, stopgap solution to Popponesset’s erosion problem.
McManus has another idea that might offer more enduring success, though it’s unlikely to ever be realized. “The best possible solution,” he says, “is to dissuade development in close proximity to areas of eroding coastal banks. Unfortunately, these areas are the most coveted real estate and much of it has already been built out. Dealing with coastal erosion requires constant vigilance and regular beach nourishment. However, given a large enough storm, no amount of nourishment can protect a given area from storm surges and subsequent damage.”
Oleksak says ongoing efforts have shown progress. “Continuing to build the dune and the slope of the beach leading up to it will help by preventing overwashes,” he says, referring to the phenomenon where elevated tides and powerful waves literally wash over a beach or spit, eroding the sand—and then dumping it inland. This scenario has notably taken place in recent years at Truro’s Ballston Beach.
“Our work has turned the tide,” Oleksak says, “with more work planned. The serious storms in January 2016 did not overwash the spit.” Save Popponesset Bay planned to add 7,000 cubic yards of sand to the spit in February, with more scheduled to arrive in March following the annual dredging of the outer channel.
Together, the Town of Mashpee and Save Popponesset Bay are doing what they can to help the spit survive the area’s tumultuous weather, with the goal of protecting a natural shorebird habitat—and the many human residents who live behind it.
He is celebrating the release of his second book: In My Footsteps: A Traveler’s Guide to Martha’s Vineyard, Schiffer Publishing (2016).
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