In a bay where waves and rising water levels are sweeping islands away, the corps is turning those few fragile pieces of land - totaling less than five acres - into a re-created 1,700-acre island with wetlands and a forest to restore decimated bird populations. Already, before all the marshes are in and the forest is planted, the number of bird species has increased from 10 in the 1990s to 170 today, including some threatened species.
The corps and U.S. scientists think they have outdone nature itself.
Nature, they say, had failed. The last ice age left land with erodible shores. The corps - in true military fashion - outfitted its land with armor, wrapping the shore in boulders as large as 4,000 pounds to shelter the new land from the open sea.
The addition of wetlands and an "upland forest" would make a perfect world for birds facing a startling loss of habitat. Where nature offered problems, Callahan noted, "we can engineer solutions."
Chris Guy, a U.S. Fish and Wildlife Service biologist who works on the project, explained, "We know what it is the birds need, so we can do a better job of designing their environment."
A better job than whom? he was asked.
"Mother Nature," he replied.
While epic in scale, the project 40 miles east of the nation's capital isn't unique. Various branches of the U.S. government - compensating for past neglect or trying to head off the anticipated effects of climate change - have embarked on highly ambitious and innovative natural projects, some under the umbrella of President Obama's America's Great Outdoors initiative, a federal government conservation program.
Perry Gayaldo, the deputy director of the National Oceanic and Atmospheric Administration's restoration center, said the large-scale efforts reflected a maturing national attitude toward the environment.
"Natural resources that were once thought to be limitless are now known to have limits, so it's important to restore some of what was lost," he said.
"In the Northeast, people used to talk about being able to walk across the rivers on the backs of the fish. People miss that."
The economic benefits are less obvious but real, officials say. The corps will spend about $14 million on Poplar Island this year, with the total cost over 40 years estimated at roughly $600 million. Of this year's expenditure, about 80 percent is for dredging the Chesapeake Bay channel in order to keep the bay open to large ships docking in Baltimore, a vital port for the region.
The traditional dredging process meant scooping sediment from the bay, then dumping it out at sea. At Poplar Island, the corps' plan eventually will use 68 million cubic yards of that dredged material, about two-thirds of what's expected to be dredged over the next 20 years.
It will stop pumping in dredge material in 2029, and the island will be considered finished in 2041. At that time, it will be 1,715 acres with its highest point about 21 feet above the water level.
Workers here freely admit that it doesn't all look entirely natural.
Still, the hope is that, even if not quite authentic-looking, the island will function naturally.