Posted on August 5, 2024
SAVANNAH, Ga. – The U.S. Army Corps of Engineers, Savannah District, used dredged sediment from the Atlantic Intracoastal Waterway to create a two-acre artificial island for birds along the East River.
Located within the Cumberland Dividings, a network of channels between Cumberland Island and the eastern coast of Georgia, the island is designed to provide nesting and foraging habitat for a variety of shorebird and seabird species.
“The island is made completely from dredge material, a mixture of sand, silt, and clay pumped from the bottom of the AIWW,” said Emily Wortman, a civil engineer in the Savannah District’s Hydraulics and Hydrology Branch. “An estimated 200,000 to 240,000 cubic yards of dredged material was used to create the bird island.”
The natural islands in this area are typically much lower in elevation due to erosion created by storms, strong wave action and rising sea levels over time.
“The lower elevations, coupled with their proximity to the AIWW, have made the islands prone to overwash from boat wakes and storms, which can threaten or deter bird nesting activities,” said Jared Lopes, a water resources planner in the Savannah District’s Planning Branch.
The Georgia Department of Natural Resources provided the District with a recommended elevation for the bird island based on productive reference nesting sites in coastal Georgia.
“This elevation considers the effects of potential boat wakes in the AIWW, combined with the impact of natural wave action and spring tides,” said Lopes. “By elevating the central part of the island to the target height, overwash is minimized, protecting nesting sites and reducing sediment transport during storm events. Additionally, this target elevation provides an enhanced vantage point for certain bird species.”
The shape and slopes of the island were also major design factors.
“Barrier Islands in this area of the Southeast typically have round or egg-shaped contours surrounded by gentle slopes which helped guide the general island design,” said Lopes. “This layout provides birds easy shoreline and intertidal foraging access. The slope was also designed to reduce the potential for egg displacement.”
Lopes further explained that the island will provide additional safety for the birds by reducing chances of predation, due to the distance of open water separating the island from shore at mean low tide.
Despite the benefits of using dredge material to create the island, the District had to overcome some hurdles to get the project approved and completed.
“It took a lot of effort and communicating between various agencies and stakeholders to get everyone onboard with the development of the island and on the same page,” said Wortman. “Building the island in that type of difficult environment was challenging too, but I think the project has been pretty successful so far.”
