Editor’s note: This is the 5th in a series of articles covering the region’s dramatically changing coastline. Click here to see all of the articles.
For two days in February of 2013, a blizzard packing hurricane force winds pounded Cape Cod. One of the areas that suffered the most damage was Ballston Beach, a popular spot on Truro’s Atlantic-facing coastline. When high tide struck on the evening of February 8, the storm surge broke through the dunes, pushing water from the ocean all the way back to the Upper Pamet River Valley.
What happened at Ballston is referred to as an overwash, rather than a traditional breach. According to a brochure created by the Town of Truro, a breach—such as those incurred in recent years at Chatham and Martha’s Vineyard’s
Norton Point Beach—occurs when ocean water forces an opening in a barrier beach and is allowed to flow in and out. The brochure explains that an overwash occurs when “ocean water and sediment pour over the beach crest with no water flowing back and returning to the ocean.”
In an attempt to repair the damage, which included further erosion of the dune and flooding in the beach’s parking lot, the Truro Department of Public Works trucked in 4,000 cubic yards of sand from Head of the Meadow, another beach in town.
According to Jay Norton, director of the Truro DPW, this did not quite solve the problem. “The dune restoration was not adequate to prevent future overwashes,” Norton says. “The
height and slope were restricted by the Natural Heritage and Endangered Species Program (NHESP).”
According to the NHESP, sand brought in to rebuild the dunes could stack up to no more than eight feet in height, and the slope could measure a ratio of no more than 10 to 1, horizontal to vertical going away from the dune’s crest.
On January 27 of this year, Winter Storm Juno tore through the repaired dunes. The high tides, combined with strong winds, caused an overwash that once again flowed into the Upper Pamet River Valley, flooding the beach parking lot and pushing sand into the marsh. At 205 feet, this opening in the dune is even wider than that of 2013.
As residents of the area are likely aware, these incidents in 2013 and 2015 are not isolated. In 1978, and again in 1991 and 1992, overwashes were recorded at Ballston with seawater mixing with the fresh water marsh system and the beach
parking lot getting flooded.
Despite this, Norton says the local drinking water is safe. “Should a wellhead be submerged in floodwaters, there is a risk of bacterial contamination, more so than saltwater intrusion,” says Norton. He adds that according to a 1998 report by a Cape Cod Commission hydrologist, in the Pamet Valley the thickness of the freshwater lens—the area where freshwater floats above seawater due to the water types’ different densities—is 120 feet. “This helps to provide a buffer for salt water intrusion,” Norton says.
This natural turmoil at Ballston Beach may seem like a negative situation, however, one local educator sees a silver lining. Eleanor Moody, head of the National Park Service’s National Environmental Education Development Program and a former biology teacher at Chatham High, views the positives. She believes the overwashes that have occurred—and the efforts to fix the damage—are great learning opportunities for the fifth-grade students who travel to Truro during the year to learn about the nature of Cape Cod.
“The overwash has been a wonderful opportunity for students to observe the dynamic landscape of our beach and dune system,” Moody says. “We spend every winter exploring the outer beach. Erosion is part of beach development and sand redistribution.” “The movement of large volumes of sand by humans,” Moody adds, “has prompted many discussions with the students about human intervention in natural processes. We are waiting to see how long it takes for the wall of sand that was built this spring to settle itself back onto the beach and then into the water.”
As for the future of Ballston Beach, Norton says several questions have yet to be answered. “Should the barrier beach remain in its current state,” he asks. “And if so what are the consequences? Should the Town of Truro continue to do short-term repairs of the dune? How is flooding of the Pamet River Valley controlled to protect private property and town infrastructure? What is the best long-term solution?”
Many of these questions are the same ones being asked by residents and officials across Cape Cod and on the Islands. And as the answers are hammered out in the coming weeks, months and years, down on the coast the beaches will continue to transform.