ACE Basin is a roughly 350,000-acre estuarine landscape on South Carolina’s southern coast where the Ashepoo, Combahee, and South Edisto rivers meet at St. Helena Sound, forming marshes, wetlands, hardwood forests, and tidal waterways. Once dominated by plantations, the region changed after the Civil War as plantation use declined. In the late twentieth century, development pressure prompted local residents and conservation groups to organize protection efforts, leading to the 1988 ACE Basin Task Force and a broad public-private partnership. Their work has preserved about 250,000 acres, making the basin a major Lowcountry conservation, research, and education landscape.