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Eel Point closed to vehicles; erosion the cause
BY PETER B. BRACE INDEPENDENT WRITER
Due to severe erosion, the Nantucket Conservation Foundation closed the end of Eel Point to vehicles indefinitely.
NCF Ecologist Karen Beattie estimates that erosion during the last 18 months has pushed the beach back into the salt marsh on the south side of Eel Point, washing away dunes held in place with beach grass and Rosa rugosa beach roses, further filling several mosquito ditches and blowing the sand back over the marsh.
"It's mainly a severe erosion issue," said Beattie, adding that there are no piping plovers or American oystercatchers nesting on this side of Eel Point.
"We've probably lost several hundred feet of beach out there in the last year-and-a-half and the way things are right now, the marsh goes right up to the water," he said.
Prior to the closing, vehicles, though driving on this sand, were technically driving on the marsh, a practice that the Foundation is bound by state and federal wetlands protection laws to prohibit on their properties.
To protect this marsh until the beach in front of it widens enough to allow vehicles to get on the beach and move down it without driving on the salt marsh, the Foundation is erecting a fence well before the former vehicle entrance to this beach with signs prohibiting vehicles but allowing beach goers to proceed on foot.
"People can drive out the marsh road until they're within 200 yards of the beach," said Beattie. "I know it's an extremely popular fishing spot, but we just can't allow vehicles on the beach. It would be a blatant wetlands violation. Not only do we want to prevent damage from people driving on the beach, we want to prevent people from getting stuck."
Beattie's theory for the cause behind the erosion is that the new opening in the barrier beach between Smith's Point and Esther Island produces strong tidal currents that flow in and out of that part of Madaket Harbor.
"I'm not an expert on currents," said Beattie, "but we really started to experience severe problems when the cut blew out Smith's Point. That's my uneducated guess."
The cut, caused by a southeasterly storm on April 19, 2007 that cleaved a channel into the 200-foot beach between ocean and harbor, has since moved westward. In so doing, it has built Smith's Point and closed in an inlet on Esther Island. The inlet formed in 1988 from the remnants of a channel between Nantucket and Esther Island after Hurricane Esther cut it off from Nantucket on Sept. 21, 1961.
Dr. Peter Rosen, a coastal engineer and Chairman of the Department of Earth and Environmental Science at Northeastern University in Boston, confirmed the potential for this new cut to move westward but, having not seen it for himself, could not comment definitively on it.
"Inlets migrate because the longshore drift fills in whichever direction the drift is heading," said Rosen. "Predominantly, the drift in Madaket is to the west. The tidal currents are keeping it [the new cut] open and the only place for it to scour is to the west. The high velocity tidal currents, which are the only thing keeping it open, eat away at the east side."
Rosen was wary about agreeing with Beattie's guess that water charging through this new cut may be causing Eel Point to erode faster than normal and said he sees no correlation between the two coastal geological changes other than the fact that they are close to each other.
"Are storms driving a significant additional amount of wave energy in there? I doubt it," said Rosen. "If, in fact, significant water is driven through the inlet beyond tidal flow. I'll give you a cautious 'maybe:
"If it keeps migrating west, it's getting to be a lot less efficient condition. Whether it leads to closure [of the new
cut], we'll have to wait and see." I
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