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The Changing Shape of the Cape & Islands: Great Point, Nantucket

A westward looking view of Great Point. Photo by Chris Seufert. Historical maps of the island from 1787 and 1835. Courtesy of the Nantucket Historical Association

Since taking on the position in 2015, Pollnac has learned about changes that have taken place in the area over the years, and others he has observed first-hand. For example, since 1995, he says about 100 feet of beach east of the lighthouse has eroded, leaving the light an estimated 300 feet from shore today. In the fall of 2012, Hurricane Sandy carved a large dent in the dunes in the same area. And though the lighthouse does not appear to be in any imminent danger, Pollnac has observed erosion’s powerful effects elsewhere on Great Point. “One thing I saw in December 2016 was flooding of the access road near the lighthouse (2),” Pollnac says. “There is an intersection where you can head toward the ocean or sound side. A few storms came from the west, one after another and, combined with high tides, flooded the road more than 400 feet from the shore.”

That intersection—and the rest of Great Point, including the land on which the lighthouse stands—is owned by the U.S. Fish & Wildlife Service. The agency’s role is to protect wildlife and wildlife habitats on the land it owns. According to Libby Herland, project leader of the Eastern Mass. National Wildlife Refuge Complex, an organization of eight wildlife refuges, this responsibility includes building and maintaining symbolic “fencing” (posts and string) in an area north of the light to keep seals from being bothered by humans, and fencing the nesting habitats of piping plover and other endangered birds. “Putting up fences protects the wildlife,” Herland says, “but it also protects the dunes by keeping people and vehicles off of them.”

Tom O’Shea, the Trustees’ director of stewardship and natural resources, has been targeting areas of critical concern using scientific models used by the Woods Hole Group, an environmental, scientific and engineering consulting firm. He says the models, which predict sea level rise and storm surge increases for Great Point in the years 2030 to 2070, paint a relatively dire picture for the area—but adds there is only so much anyone can really do. “We are not sure how proactive we can be,” O’Shea says. “We need to wait for more sediment-transport analysis. We want to be smart about any adaptations we make.”

Analyzing the sediment, he says, can give researchers information about where accreted material has come from and where eroded material has gone. Once the study is completed, O’Shea says the Trustees will have a better understanding of how the beach will likely change, and may decide to implement new technologies currently under development to help shorelines adapt to or withstand erosion. These include a new type of fencing that helps disperse wave energy, or the installation of oyster reefs to help the beds—which protect shorelines from erosion—grow faster.

Ultimately, O’Shea says man can—and should—only do so much. “All barrier beaches are dynamic,” he says. “It’s important to let the natural processes occur. We need to not take action unless it is really necessary.”

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