Restoring and Recycling at the John H. Chafee Wildlife Refuge

Bags of clam shells shore up what will become restored marsh.

The temperature along the bank of Narrow River is in the 30’s, and gusts of wind have a way of sneaking under coats, like someone is pouring ice water down the neck. The area seems devoid of life, save for a congregation of gulls gathered around a long black tube that resembles nothing so much as a fire hose. The hose wends its way to a floating craft on the river, where an engine drones. This is a dredge, its noise proclaiming the new phase of a salt marsh restoration at the John H. Chafee National Wildlife Refuge.

“We saw the opportunity to make the river a little wider for boats and kayaks and give them more space,” says Ben Gaspar of US Fish and Wildlife (USFW). “We also saw that it could be excellent eel grass habitat, and so when we were dredging, we went to the eel grass depth.” The restored area has varying “target depths”, so that different spots are filled to different levels in order to encourage things like eel grass beds and marsh grasses to grow. Eel grass is an essential part of the ecosystem, providing shelter for a wide variety of marine life.

Moving mud
The work is part of a $1.4 million, multi-year cooperative agreement between The Nature Conservancy (TNC) and USFW. The federal funds are part of the Hurricane Sandy recovery projects, and this one involves over a dozen federal, state, and local organizations. In all, the project will affect 30 acres of marsh along Narrow River altered by erosion from storms like Sandy, along with sea level rise. USFW wanted to address salt marsh loss at two refuges (Chafee and Sachuest Point). When the federal funds became available, the refuge manager, Charlie Vandemoer, reached out to TNC to help make it happen. Vandemoer says that some salt marsh banks have eroded over three feet, and over a hundred acres of marsh has been degraded because of sea level rise.

The dredge boat currently in use on Narrow River. Photo: Tim Mooney, TNC

The Conservancy and USFW say the latest phase will move 700 cubic yards of material from the river to the shore to restore marshland that has been lost. The dredge work from today sucks material from the bottom of the river and deposits it on the shore where the marsh has deteriorated. Thus, the dredged material is not only being recycled, it is also the same composition as that of the surrounding area. This type of symmetry avoids unintended consequences that may arise from bringing in materials from other locations. Gaspar relates the story of another project where material had been brought in from elsewhere, only to find that the iron content in the soil would prevent native plants from growing.

From the ocean to the table and back to the ocean
Even in this case, though, the action from currents, storms, and boats would continue to erode the new material. With some projects, coir logs are used. Coir logs are made from coconut fiber and rolled into “logs”. They are then placed at the edge of a protected site to slow erosion. While they are useful in some cases, it was determined that they would deteriorate too rapidly in an area with this much water movement.

According to TNC’s Tim Mooney, the organization decided to experiment with an alternative. “After the coir logs didn’t hold up, our consultants suggested using hard materials to stabilize the leading edge of the marsh and abate erosion. TNC was experimenting with bagged oyster shell in Ninigret Pond at the time, in a precursor to our current reef building work. We had a pile of surf clam shells that were too broken up for reef restoration, so we worked with USFWS to bag it up and make it available for marsh creation at Chafee NWR. From a regulatory standpoint, it was important that it was biogenic (produced by living organisms) material. So far, the shell bags are holding up very well to the wave energy on the marsh.” The shells came from a prior arrangement with Matunuck Oyster Bar, wherein the restaurant would keep empty clam and oyster shells. Periodically, the shells would be picked up and brought to a South County location, where they complete a six month stay to allow them to cure.

Time and tides…
The dredging window must be done from early November through December in order to avoid disturbing winter flounder. On this day, the crew from a contracted company is reporting an issue with hard material at the bottom. The dredge does its work following a strict grid pattern to insure consistent results. The appearance of the harder material is causing the dredge to tilt off in a different direction. Gaspar will report that, and the team will discuss what new measures will be taken to compensate.

There are about a dozen organizations involved in the whole restoration project. When that happens, there is a mountain of paperwork involved. TNC provided a lot of the expertise in contracting to get the varying organizations needed to do all the phases of the project. “One of TNC’s strengths is contracting and project management, and that’s primarily what we’re bringing to the work,” said Mooney.

Ben Gaspar.USFWS.Chafee NWR. Photo: Tim Mooney, TNC

Learning as they go
As the dredge resumes work, the gull meeting is hastily adjourned in favor of a short flight to the now gurgling black hose. It begins to spew water, sand, and marine organisms, the last quickly snapped up by the gulls.
Once this project finishes, USFW will assess things like salinity level and use equipment that measures the depth of the marsh (mud) itself. These, along with other measures, will encourage the long-term goal of restoring and maintaining the marsh. Tim Mooney says the need both in Narrow River and other places requires action now, rather than later. “We approach these projects with the best science we have. Then we watch them closely and adjust (our techniques) for the next time. We don’t have time to wait, as marshes are disappearing rapidly.” As if to underscore the need for preservation, a Great Blue Heron glides into the marsh and lands its lanky frame a dozen yards away.
Gaspar maintains high hopes for the future of the project: “Even as we’re working out here now, TNC is rounding up volunteers to come out and plant in the spring. It’s very exciting.”

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