Preparing for rising seas

On one of the coldest days of the year, Wenley Ferguson fights the wind at the edge of Quonochontaug Pond in Charlestown. Bundled in a parka and knee-high rubber boots, she watches as workers use two large hydraulic dredges to pump a slurry of sand and water a quarter mile through an orange flexible pipe and onto the adjacent salt marsh in an effort to raise the elevation of the wetland. With flocks of gulls and shorebirds called dunlin gathering at the outflow pipe to forage for tiny marine creatures, two bulldozer drivers push the sandy sediments around on top of the delicate marsh, grading the site to create areas of high- and low-marsh habitat, as well as drainage channels so water does not pool on the surface as the tide recedes.

The habitat restoration coordinator for Save the Bay, Ferguson and Caitlin Chaffee from the Rhode Island Coastal Resources Management Council oversee the team of workers as they

Roy Carpenter's Beach after Super Storm Sandy (Michael Cevoli)

endure the challenging conditions to complete the first stage of what officials hope will save the marsh from rising seas.

“It looks a bit like a desert at the moment,” admits Ferguson, who calls the effort a sediment placement project. In a year or two, however, after native marsh plants have been planted and nature has had a chance to carve its signature into the project, the marsh will look and work like it did before sea level began its rapid ascent.

“We’re taking these extreme measures to place sediment on degraded salt marshes because we’ve seen widespread loss of salt marsh vegetation over the last 15 years,” says Ferguson. “A healthy marsh can build elevation through its root matter or through the accretion of sediments, but our marshes aren’t keeping pace with sea level rise.

During the last 20 years, sea level has risen an average of 5 millimeters per year, but local salt marshes are building elevation at just 2 millimeters per year. “And millimeters matter,” Ferguson notes. While salt marsh vegetation thrives on the twice daily influx of water from the tides, the rising sea level has meant that many of the Ocean State’s salt marshes are becoming permanently flooded, killing the vegetation where rare birds nest, and negating the marsh’s ability to cushion surging storms.

The Quonochontaug project follows similar efforts at Sachuest Point National Wildlife Refuge in Middletown, the Narrow River in Narragansett, and Ninigret Pond in Charlestown.

            A decade ago it would have been unthinkable for Ferguson to stand idly by as dredged material was dumped on a salt marsh. She spent much of the 1990s and 2000s removing fill and other impediments to the natural tidal flow at more than a dozen marshes damaged by human disturbances in the state.  Under normal circumstances, Ferguson may have been one of the first to stand in the way of a heavy bulldozer driving over the fragile marsh plants. But the circumstances these days are anything but normal.

            According to a gauge in Narragansett Bay, sea level has risen 11 inches since 1930, most of it in the last three decades. The National Oceanic and Atmospheric Administration recently raised its estimates for future sea level rise to five feet by 2050 and more than 11 feet by 2100. During moon tides and major storms, water levels will get even higher. And that means that most of Rhode Island’s salt marshes – and much of the rest of the coastline – will soon become flooded. The changing climate is driving other dramatic changes in the Ocean State as well, from increasingly damaging storm runoff to degraded forests and heat-related illnesses.

             The state of Rhode Island and its coastal communities, along with coastal businesses, residents and some inland towns, are beginning to plan for the inevitable implications of climate change. Structures are being raised, barriers are being built, and numerous other strategies are being deployed in anticipation of....

Read the rest of this story in the June 2019 issue of Rhode Island Monthly magazine.