Silty plume at Cow Bay was red but not dangerous

Beach nourishment project at Bend in the Road attracts interest.

Sediment from an up-Island pit is piled along the shoreline as part of the Cow Bay beach nourishment project. Suspended sediment was seen in the adjacent water. —Stacey Rupolo

A beach nourishment project underway at Bend in the Road Beach and Cow Bay created a plume of reddish silt that moved along the shore, catching the attention of many drivers on Beach Road.

“The Cow Bay Association is paying for this,” Jane Varkonda, the conservation agent for the town of Edgartown, said of the beach nourishment project. The private group undertook the project to replenish the beach, to prevent undermining of cabanas, and to preserve an access road to the property of Cow Bay Association homeowner Dean Metropoulos. “There is nothing to worry about,” she said. “Everything is within the perimeter of the permit.”

The association has undertaken this task before. Between 2008 and 2013, they replenished the sand on the beach. In 2010 they used sand dredged from Sengekontacket Pond by the town of Oak Bluffs.

Ms. Varkonda said that the source of the sand this time is a new pit opened at John Keene Excavation in West Tisbury. “[The sand] is orange because it hasn’t been exposed to the air,” she said. “It will eventually bleach out.” The orange color is caused by iron in sand; this led some callers to the town to express concern that the iron would feed an algal bloom and be harmful to shellfish.

“Rick Karney [director of the Martha’s Vineyard Shellfish Group] investigated,” Ms. Varkonda continued, “and he found that it isn’t the right kind of iron.” Other reports claimed that shellfish in Sengekontacket Pond were being smothered, but Mr. Karney said that wasn’t the case, according to Ms. Varkonda.

Paul Bagnall, the shellfish constable for the town of Edgartown, agreed. “It’s not harmful to the shellfish,” he said of the red plume. “It’s just a nuisance when it enters the pond, and it gives you an idea of how much sediment is moving around Martha’s Vineyard. They can’t help having it suspended like that; it’s best to do it this time of year.” He noted that sediment is always in motion, but the red color of this plume served as a sort of marker to make it more noticeable. Bagnall said that in the “grand, mass balance of things,” the amount of iron in the sediment was not significant.

The beach project is necessary, Ms. Varkonda said, because there is no longer a source of sediment to maintain Bend in the Road Beach naturally. The longshore current moves west to east from Oak Bluffs, but groins and other “hardscaping” features of the shoreline there, such as jetties, prevent sand from moving eastward. The Cow Bay area sand moves toward Edgartown, leaving the Bend in the Road Beach “starved.”

Permissions for the project come from the Commonwealth of Massachusetts, Ms. Varkonda said. It has been licensed under Chapter 91 of state General Law, the Public Waterfront Act, and received a water quality certificate from the Department of Environmental Protection. The Edgartown conservation commission also issues an order of conditions that indicates that the plan complies with the Wetlands Protection Act and the town’s conservation bylaw.

The U.S. Army Corps of Engineers also issues a permit. “Our jurisdiction is over all work below the high-tide line,” said Kevin Kotelly, permit project manager for the Army Corps. “The town submitted a project design, a plan, and site photos. We reviewed it with a number of other agencies.” He listed the U.S. Environmental Protection Agency, National Marine Fisheries, Coastal Zone Management, the state Department of Marine Fisheries, and the state Department of Environmental Protection.

The Army Corps permit, which is good for 10 years, also covers dredge work being done in Katama Bay and near the Edgartown Lighthouse. The permit was issued in September 2014. Mr. Kotelly said that he was not aware of the most recent activity, and said that he would be calling the consultant to the Cow Bay project to make inquiries.

“They need to be in compliance with our permit,” said the regulatory engineer. “If there’s a turbidity plume, that could be a problem.”

After speaking with the Woods Hole Group consultants for the project, Kotelly reported that they found there was no cause for alarm. The plume had been present for one or two tide cycles, they said, and then had disappeared.