Tidal gauge keeps waters of Goshen Cove from stagnating

Employees of the Woods Hole Group based in East Falmouth, Mass., including Dan Rogers, left, a field biologist/diver, and Michell Buck, a coastal engineer, begin the process of collecting data from the Goshen Cove in Waterford to study the effects of large storms on the cove Thursday. The crew is installing a tidal gauge, which will transmit data to be analyzed to find out why the channel shifts and changes its path after a storm such as Sandy.
Employees of the Woods Hole Group based in East Falmouth, Mass., including Dan Rogers, left, a field biologist/diver, and Michell Buck, a coastal engineer, begin the process of collecting data from the Goshen Cove in Waterford to study the effects of large storms on the cove Thursday. The crew is installing a tidal gauge, which will transmit data to be analyzed to find out why the channel shifts and changes its path after a storm such as Sandy. Tim Martin/The Day Buy Photo

Waterford - In hip waders and rubber boots, Mitchell Buck dropped himself into the chilly waters of Goshen Cove Thursday morning, then sloshed through the shallow pond in search of a perch for a device that could help solve a persistent problem in this important tidal wetland.

"We're going to install a tide gauge off this bridge to see how the tides in this pond compare to the tides in the ocean," said Buck, coastal engineer with the Woods Hole Group, an environmental consulting firm. "It's that daily tidal flushing that keeps the pond from becoming stagnant."

Looking on as Buck and Dan Rogers, field biologist with the Woods Hole Group, began their work on the cove was Mark Darin, supervisor of Harkness Memorial State Park. The brackish cove, where the waters of Long Island Sound mix with the fresh waters of Ledges Brook, is the centerpiece of the 80-acre William Niering Natural Area Preserve, which takes up the west side of Harkness.

With its historic mansion, manicured gardens and picnic area overlooking the Sound, Harkness draws some 250,000 people a year. Except for a short walking trail and viewing platform over the marsh, though, the Niering area is off-limits to humans, set aside for the many shorebirds and other wildlife that use it.

Among the challenges that come with operating a popular park side-by-side with a nature preserve, Darin said, is keeping visitors and their dogs away from the nesting area for threatened piping plovers and least terns on the barrier beach at the end of the cove. He doesn't normally welcome humans wading through the cove but was making an exception for Buck and Rogers in the interest of figuring out how to tame the outlet between the cove and the Sound in a way that will both improve the marsh and protect the terns and plovers.

"When the outlet to the cove is flowing nicely, it creates a natural barrier," keeping people out of the nesting area, he said.

The problem, explained Tom Tyler, director of state parks, is that the outlet channel is such a changeable waterway, shifting dramatically each time there's a big storm. Often, soon after it moves, the channel clogs with sand, and water flow to the marsh is constricted. Sometimes in the summer months the pond at the center of the marsh becomes stagnant, emitting an unpleasant odor.

"It's a really dynamic piece of shoreline, and after each storm the details of the problem are different," Tyler said. "Our goal is to find a permanent or semi-permanent solution that's affordable."

Darin said Harkness crews have to reopen the channel about four or five times a year. About half the time, he said, strong backs and shovels will do the job, but tractors are required at other times.

"There have been a couple of times when we've had to bring bulldozers in," he said. "But we can't bring any machinery in during plover nesting season," which lasts from March through September.

After Hurricane Sandy, he said, the channel widened and moved eastward, "but since then it's started meandering back.

Keeping up with the shifting cove outlet, he said, poses challenges because of the park's limited manpower. But left to clog, it can erode the dunes the plovers and terns depend on for their nesting area and cause flooding of the upland marsh including areas near homes.

In search of a solution, Tyler said, the state Department of Energy and Environmental Protection hired the engineering firm Fuss & O'Neill to study the cove and develop a plan. Tyler said he hopes to have the plan by this summer.

As subcontractors for Fuss & O'Neill, the Woods Hole Group is compiling the environmental data on the cove, including tidal flows and water depths. Buck and Rogers waited until high tide Thursday to launch their 12-foot aluminum flat bottom boat out onto the cove, where they used sonar equipment to measure depths.

The tide gauge, Buck explained, will log a month's worth of data before they come back to collect it. He fixed the gauge, resembling a fat metal rod, to a wooden block, then secured it to a piling that supports an old wooden bridge built by the family that owned the marsh area before the state acquired it. Holding the gauge in place are a series of plastic ties and metal hose clamps covered with electrical tape to guard against the corrosive sea water.

"You never know," Rogers said, and the two tightened yet another plastic tie around the gauge, just to make sure. "The ocean's stolen gauges from us before."

j.benson@theday.com

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