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Wednesday, January 25, 2017

Charlestown among towns most at risk from sea level rise

By FRANK CARINI/ecoRI News staff

Photos by Will Collette
With 400-plus miles of coastline, Rhode Island features a marvelous collection of beautiful bluffs, popular beaches, favorite fishing holes and scenic waterfronts. The state’s coastal landscape also includes often-overlooked salt marshes, without which Rhode Island’s nickname would be much less tourism friendly.

These unique ecosystems are a priceless resource with irreplaceable benefits to both people and wildlife. The Ocean State is losing and has lost thousands acres of salt marsh to development and a changing climate. 

It’s been estimated that the state has lost about 60 percent of its salt marshes, many of which were filled with mud and sand dredged during navigation projects or filled in with other waste materials. Downtown Providence, for instance, was once known as the Great Salt Cove, prior to its filling.

Salt marshes are the protectors of Rhode Island’s most important cultural, economic and environmental resource, Narragansett Bay. 

But more than 50 percent of the bay’s salt marshes have been destroyed during the past three centuries. Much of the remaining marshes have been diminished by coastal development, a changing climate and mosquito ditching. Mosquito ditches are narrow channels that were dug to drain the upper reaches of salt marshes. 

It was believed that such efforts would control mosquito breeding, but all that work did was drain salt marshes and kill off mummichogs, a mosquito-eating fish that are important prey for herons, egrets and larger predatory fish.

Salt marshes are shoreline wetlands that are flooded and drained by salt water brought in by the tides. These intertidal ecosystems — foraging habitat for fish, shellfish, birds and mammals, and home to nursery areas and spawning grounds — are essential for healthy coastlines, communities and fisheries. They are an integral part of Rhode Island’s economy and culture.

Salt marshes play an important role in Rhode Island’s fishing/shellfishing industry. The economic value of salt marshes related to recreational and commercial fishing activities is estimated to be $6,417 an acre, according to James Boyd of the Coastal Resources Management Council (CRMC).

They help Rhode Island’s tourism/outdoor-recreation industry generate some $2 billion annually. The many vistas afforded by the state’s salt-marsh landscape also contribute immeasurably to the Ocean State’s beauty and peacefulness.

Healthy salt marshes help communities, buildings, infrastructure and the environment better withstand the impacts of sea-level rise and coastal storm surge. Salt marshes protect shorelines from erosion by buffering wave action and trapping sediment. These vital ecosystems reduce flooding by absorbing rainwater, and protect water quality by filtering runoff and metabolizing excess nutrients, such as nitrogen.



But storm surge and wave erosion, combined with the lack of replenishment from estuaries whose rivers have been dammed or choked off by centuries of development, have left once-hardy tidal-marsh ecosystems at a point where salt-marsh elevations can’t keep up with sea-level rise, according to Jennifer White, a biologist with the U.S. Fish & Wildlife Service.

For example, the coastal portion of the Sapowet Marsh Wildlife Management Area in Tiverton has experienced more than 90 feet of shoreline erosion in the past 75 years, according to the Rhode Island Department of Environmental Management (DEM).

The Nature Conservancy and the U.S. Fish & Wildlife Service are working to restore and strengthen salt-marsh habitat at Sachuest Point National Wildlife Refuge in Middletown to better withstand the impacts of sea-level rise, coastal storm surge and coastal erosion.

The East Coast, from North Carolina to Boston, is considered a hot spot for sea-level rise, with coastal waters climbing three to four times faster than the global average, according to the U.S. Geologic Survey.

The current sea-level rise estimates for Rhode Island are a foot by 2035, 2 feet by 2050 and 7 feet by 2100. Areas at most risk for sea-level rise — Barrington, Charlestown, Narragansett, North Kingstown, Warren and Westerly — are already experiencing the death of salt marshes. A 5-foot rise in sea level is expected to wipe out 87 percent of the state’s remaining 4,000 acres of coastal wetlands, according to CRMC.

Although coastal areas go through natural periods of change, there has been a net loss of sediment during the past few decades in Rhode Island, according to CRMC’s Shoreline Change Special Area Management Area (Beach SAMP), and many municipalities have faced or are facing erosion issues on both public and private beaches. The agency also has noted that the most eroded portions of Rhode Island’s coastline have lost more than 250 feet of beach in the past 50 years.

Salt marshes and other wetlands are highly sensitive to development, which can disrupt their highly valued services. Polluted stormwater runoff from inland development can damage salt-marsh health. 

This runoff from roads and other impervious surfaces, and nutrient-rich runoff from fertilized lawns and agricultural areas and from septic systems and cesspools, also can degrade freshwater wetlands.

Balancing development interests with a healthy environment is a difficult task, especially when the policies, regulations and guidelines that govern development are constantly under attack, underenforced or ignored.

Threats of litigation, special interests and a state economic development plan that preaches “cranes in the sky” are applying considerable pressure on the Ocean State’s dwindling collection of healthy salt marsh.

Art Ganz, president of the Salt Ponds Coalition, told ecoRI News late last year that no one is enforcing coastal development. “We have the tools, like the Beach SAMP and Stormtools, that do a good job planning and thinking about the changing coastline and how it should be developed, but there’s been no implementation yet. Nobody wants to be the first guy to say no and get slapped with a lawsuit.”

During the 2016 General Assembly sessions developers were given a boost with the passage of the wetland buffer bill that allowed wetland buffers to be included in determining the number of homes or apartments that can be built on a parcel.

The legislation was a surprise follow-up of a law passed in 2015 that allows the state to establish universal protective zones for freshwater wetlands. Rhode Island development was given a similar boost in 2013, with passage of a law allowing unbuildable sloped land to be included in lot sizes.

Ganz, who retired from DEM’s Department of Natural Resources in 2005 after 35 years, noted that despite CRMC cease-and-desist orders development continued along Green Hill Beach in South Kingstown. He said some of the properties there will be under 5-9 feet of water when the next 100-year storm strikes.

“Coastal planning is ignored and the problem keeps magnifying as we keep developing places,” Ganz said. “The awareness is there but enforcement is lacking. We’re using taxpayer money to jack up houses that should have never been built. Where are we going? I don’t know.”

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