Island Reborn From Dredge Spoils

Swan Island, situated in Maryland's Tangier Sound, has undergone a remarkable transformation. Years of erosion and subsidence had diminished its protective barrier role for the community of Ewell. In 2018, a unique opportunity arose when engineers repurposed sediment from routine dredging of navigation channels to rebuild the island.

Approximately 60,000 cubic yards of dredged material were used to restore about 12 acres of Swan Island by 2019. This effort created a varied habitat of higher and lower marsh, alongside dune areas, using native plants like American beach grass and Spartina species.

Engineers implemented containment measures using coconut-fibre logs to secure the sediment. Challenges arose as the sediment was sandier than anticipated, influencing precise placement and plant selection. Additional armouring was used on some shorelines for erosion resistance, with around 200,000 plants installed.

Following completion in 2019, a comprehensive monitoring program was initiated by various agencies, including NCCOS and the US Army Corps of Engineers. This tracked sediment, ground levels, water movement, and ecological conditions to assess the island's performance and adapt management strategies.

Initial monitoring revealed strong growth in high marsh areas but less success in low marsh. This led to the addition of 25,000 Spartina alterniflora plants, demonstrating an adaptive management approach. The project's data informs future coastal restoration projects facing erosion and rising sea levels.