The Changing Shape of Popponesset Beach, Mashpee
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.
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