by Steve Droter
February 26, 2013
Part construction site, part mud pit and part wildlife refuge, the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island, Md., tackles two unique challenges in the Chesapeake Bay.
First, sand and sediment accumulate in the Bay’s vital shipping channels—particularly during heavy rain events like Tropical Storm Lee in 2011—and threaten to block cargo ships that allow the Port of Baltimore to contribute $2 billion each year to the region’s economy.
On the other hand, sea level rise, sinking land and increasingly frequent strong storms are quickly eroding away the Bay’s few remaining islands, threatening the survival of iconic wildlife species and critical habitat.
Poplar Island, for example, spanned more than 1,100 acres in the mid-1800s and supported a small community of families, farmers and fishermen until it was abandoned in the 1930s. When restoration began in the 1990s, four scattered acres were all that remained—less than half a percent of the island’s historical size.
But the island that was nearly destroyed is now destined to be rebuilt using 65 million cubic yards of sedimentary silt—imagine a giant cube of mud a quarter mile long in each direction—dredged up from the bottom of the Bay.
In 1998, the U.S. Army Corps of Engineers began to construct stone “containment dykes.” The walls are 10 feet tall and surround Poplar Island’s former footprint, and the island has been divided into six massive containment cells for building island habitat.
The western half of the island, surrounded by an inner ring of 27-foot dykes, is being transformed into 570 acres of forested upland island habitat similar to that of neighboring Coaches Island.
Coaches Island, once vulnerable to the same forces that washed away its neighbor, supports upland species like bald eagles and provides a shallow inlet utilized by nesting diamondback terrapins in the summer and migratory waterfowl during winter.
The eastern half of Poplar Island is further divided into 14 “sub-cells” undergoing various stages of wetland construction and management.
Low-lying wetlands are created through a four-step process. First, dredged sediment is brought in on barges by the Maryland Port Administration, mixed into a watery slurry, and pumped into each cell at precise levels.
As the slurry dries, it forms a massive crust—a vast, other-worldly landscape—that is the base for building habitat.
Next, heavy machines carefully grade the crust and excavate ditches that will function as tidal creeks in the completed marsh.
Then a spillway is opened to expose the new landscape to tidal flow, and water is allowed to move between the Bay and the newly built marshland.
Finally, individual plugs of smooth and saltmeadow cordgrass are planted row upon row into the nutrient-rich soil.
These native plants are capable of withstanding strong storms while offering food and shelter to the 175 species of shorebirds, songbirds, waterfowl and raptors that now visit Poplar Island.
Poplar Island's marshes offer protection and isolation from human and mammalian predators, and the open waters along its perimeter provide feeding opportunities for diving ducks like buffleheads, scaups and long-tailed ducks.
The U.S. Fish and Wildlife Service (USFWS) manages the island’s vegetation and wildlife—including less welcome species like the Canada goose. Fences and fluttering pink flags help deter geese and prevent them from overfeeding on expensive marsh grass.
On our visit in January 2013, USFWS wildlife technician Robbie Callahan led a monitoring team to assess the density of muskrat huts in the marsh. The semiaquatic rodents, though a critical part of the wetland ecosystem, are controlled to prevent damage from overpopulation.
The USFWS also monitors avian predators—like the northern harriers that feed on small rodents—and migratory waterfowl, attracted to Poplar Island during their spring and fall trips along the Atlantic Flyway.
With the help of USFWS experts, Poplar Island is able to provide a range of Bay species with the safe nesting habitat that only a protected, well-managed island can.
Even sunken barges—placed here in the mid-1990s as “breakwaters” in an attempt to retain the island’s remnants—have become host to nesting ospreys and black-crowned night herons.
According to the USFWS, Poplar Island is well on its way to becoming a keystone wildlife refuge. “Poplar Island is an important refuge,” said USFWS biologist Pete McGowan, who specializes in waterfowl and island restoration. “There are species that are highly dependent on these remote island habitats. And this is a habitat type that is rapidly disappearing from the Chesapeake Bay. We need to do what we can to maximize the remaining island habitat that we have, and create new island habitat whenever possible.”
The Paul S. Sarbanes Ecosystem Restoration Project is scheduled for completion in 2041, with a final price tag estimated at $1.4 billion over 45 years. Rebuilding Poplar Island is an enormous, expensive and painstaking process—but its virtues of “beneficial use” have been extolled throughout the conservation and business communities alike, and it has become a "win-win" for the Bay and all the watershed provides.
View more photos on the Chesapeake Bay Program Flickr page.