ANNAPOLIS, Md. – About a decade ago, a bird species facing a rapid population decline vanished from one of its previously documented haunts on Maryland’s Eastern Shore. What had once been a swath of ideal high-marsh habitat for saltmarsh sparrows near Deal Island now flooded too often.
Experts cite sea level rise as one of the main drivers of the increased flooding, which in turn accelerates erosion and, ultimately, the loss of the marshes.
Saltmarsh sparrows build their nests close to the ground amid wetland grasses. With high tides and storm surges inundating those nests more often, the birds fled, said David Curson, director of bird conservation for Audubon Mid-Atlantic.
“If we don’t take action, nearly all of the marshes in the [Chesapeake] Bay will be lost to erosion by the end of this century,” said Curson, who has surveyed the Deal Island population for years. “This would be a real disaster because of the essential ecosystem services they provide.”
After four years of planning, a $13 million effort is underway to test a possible solution. The U.S. Army Corps of Engineers is using mud dredged from a nearby river to raise the height of a section of marshland that once hosted the sparrows.
A dredge operated by Cottrell Contracting Corp. of Chesapeake, VA, started siphoning muck from the bottom of the lower Wicomico River in mid-October. That is routine. Since the 1890s, the river has been dredged every few years to maintain adequate depth for ships traveling to Salisbury. The port handles 1 million tons of cargo per year, making it the state’s second-largest water hub after Baltimore.
What’s different is where the dredged material is being placed. Typically, it has been unloaded wherever a willing landowner could be found and environmental hurdles could be cleared.
When Wicomico County and the Army Corps could no longer locate a suitable site on the lower half of the river a few years ago, they began looking farther afield. The partners prioritized sites at the greatest risk of washing away. A spot within the state’s 13,000-acre Deal Island Wildlife Management Area (WMA) easily fit the bill, they said.
“You can see the marsh is breaking up,” said Curson as he displayed photographs during a virtual public meeting for the project.
The project entails mixing the dredged silt with water and pumping the resulting slurry through a temporary 9-mile pipeline. There, workers spray the material onto a 75-acre plot of badly eroded wetlands that lie between the Manokin River and the WMA’s main impoundment.
That phase of the project is scheduled for completion by mid-February. If all goes according to plan, the targeted acreage will receive 140,000 cubic yards of fresh earth, raising its height an average of 1.5 feet. The Army Corps plans to restore vegetation over two years by spreading seeds from the air and planting grasses by hand.
A second phase of dredging on the upper portion of the river is scheduled for late 2024, but that spoil is ticketed for a site near Salisbury.
At the Deal Island WMA, the project should convert “low marsh” to “high marsh,” making it hospitable once again for saltmarsh sparrows, Curson said.
The birds are mostly gray with orange face markings. But they’re rarely seen or heard, keeping mostly to themselves within the shelter of the surrounding grasses.
These saltmarsh ghosts are fading even further. The number of saltmarsh sparrows, which inhabit marshes along the Atlantic Ocean and upper Gulf of Mexico, has declined 75% since 1990. If nothing is done, experts fear they could go extinct by 2050.
The project will have benefits beyond helping sparrows, supporters say. The firmer land should help slow erosion within the WMA, which is considered a critical stopover for migratory birds and waterfowl.
Other projects in the Bay watershed have used dredged material to create habitat. Since the 1990s, for example, the Army Corps has been restoring and expanding Poplar Island out of mud dredged from channels leading to the Port of Baltimore and the Chesapeake and Delaware Canal. Poplar Island, growing just off the coast of Talbot County, started with open water, presenting planners with a fresh palette.
The Deal Island project is different because it seeks to raise the elevation of saltmarshes and mud flats to keep them from disappearing. The Army Corps has used dredged material to raise elevations for habitat purposes in other parts of the country, but this is its first effort in the Bay region, officials say.
“This is a real opportunity to create habitat,” said Bart Wilson, a geologist with the U.S. Fish and Wildlife Service, which is partnering on the project. “This is the kind of habitat we want to expand not only in the Chesapeake but in the Mid-Atlantic and the entire Northeast.”
A marsh restoration project within the sprawling Blackwater National Wildlife Refuge in Dorchester County has much in common with the Deal Island work. Both are what experts call “thin-layering” projects. Traditional “thick” applications provide more security from sea level rise but have often smothered life in the muck, including the existing plants.
The restoration at Blackwater, though, wasn’t an Army Corps venture. The Corps dredges huge amounts of material while maintaining 300 miles of navigation channels within its Baltimore district. Deal Island will test whether some of that material could be used to stem marsh losses around the Bay, said John Moulis, a wildlife official for the Maryland Department of Natural Resources, which oversees the Deal Island WMA.
“If we could capture material on a scale that comes from the navigation section dredging and if we could figure out a way to marry the two initiatives, perhaps this is something we could use into the future to address marsh habitat loss,” Moulis said.