CHATHAM – The town's shoreline has always been dynamic, but the fallout from changes in 2017 is likely to be felt for years, perhaps decades to come.
“This has been an active year,” said Coastal Resources Director Ted Keon.
It was a bit of a “double whammy,” he said, with changes on both eastern and southern shorelines. As the town heads into 2018, plans are underway for a large-scale, two-year dredging and beach nourishment project to address erosion along Nantucket Sound beaches, while fishermen, boaters and shoreline observers are keeping a close watch on the eastern shore's dynamic inlet and barrier beach system.
For months, the southern end of North Beach Island had been extending, squeezing the navigation channel through the 1987 inlet across from the Lighthouse Overlook. The channel shifted daily and it wasn't at all certain that it would remain open and navigable. Meanwhile, South Beach extending south from Lighthouse Beach was growing narrower and narrower and was frequently washed over during extreme high tides and storms.
On April 1, a storm punched a hole in South Beach about a half mile south of Lighthouse Beach. Within a day it was 150 feet wide at low water and deep enough for a 20-foot boat to traverse. The new breakthrough, dubbed the April Fool's or Fool's Cut, quickly widened and in a short time was being seen as a new, quicker and safer route linking Nantucket Sound to the Atlantic. The inlet deepened and stabilized, and by the summer it was being used frequently by recreational and commercial boaters.
It also had an impact on the 1987 inlet and the navigation channel, which continued to degrade, to the point where officials are worried about its continued viability.
Nearly three months later, in late June, the northernmost tip of North Beach Island was cut off during another storm, widening the 2007 inlet. The orphaned lobe of sand eventually disappeared. Both of the new cuts in the barrier beach system are the anticipated progression of that system's cycle of erosion and rebuilding, Keon and other experts say. This set up a duel between the 1987 and 2007 inlet for dominance in tidal exchange – and boat traffic – between Pleasant Bay and Chatham Harbor and the Atlantic. Experts expect the northern inlet to win out.
“We're seeing that play out at this point,” Keon said.
Erosion accelerated along Nantucket Sound, showing most significantly at Cockle Cove Beach and Harding's Beach, the result of the interruption of the natural west to east flow of sand by dozens of groins from Yarmouth to Chatham. Planning navigation dredging that would have produced sand to bolster those beaches hadn't happened, which left them more vulnerable than usual. That was especially evident at Cockle Cove, where an October storm chewed up a section of the parking lot.
Harding's Beach is the town's most profitable paid beach, and the loss of beach front – this summer high tide reached the foot of the dunes in many locations – threatens a significant revenue source. To help restore the beaches, Keon and Natural Resources Director Robert Duncanson presented a plan to selectmen in November for a two-year, $750,000 dredging and beach nourishment project. The town is fortunate to have a ready source of sand to mine in the area of the Morris Island cut, where, not coincidentally, a nearly unlimited amount is being swept in through the 2013 break in South Beach.
The plan, endorsed by selectmen, calls for nourishing Cockle Cove Beach next year at a cost of $450,000, with Harding's Beach following in fiscal 2020 at $300,000. Cockle Cove should be on a nourishment cycle of approximately ever five years, with Harding's Beach nourished every seven years, Keon said.
He pointed out that none of this is surprising. Both the south side beaches and the barrier beach on the east side of town have been eroding and accreting for hundreds of years. Large-scale inlet migrations and beach movements “are almost commonplace to the community.” Yet because of development in the last half century and intense recreational use, it's more noticeable and has a greater impact.
In the coming year, Keon and other coastal watchers will be paying close attention to the changes in the 1987 inlet and the Lighthouse Beach-South Beach area, as well as how the widening of the 2007 inlet impacts the inner shoreline and shoaling in the bay and harbor.
“Both of those inlet systems are going through changes right now that will continue,” Keon said. “It's important to watch and monitor them.”