The Mobile–Tensaw River Delta is the largest river delta and wetland in Alabama. It encompasses about 260,000 acres in a 40-by-10-mile area and is the second-largest delta in the contiguous United States. This large river delta is around 45 mi long and averages 8 mi wide, being 16 mi wide at its widest point. It covers roughly 300 sq mi. Of its 260,000 acres, …The Mobile–Tensaw River Delta is the largest river delta and wetland in Alabama. It encompasses about 260,000 acres in a 40-by-10-mile area and is the second-largest delta in the contiguous United States. This large river delta is around 45 mi long and averages 8 mi wide, being 16 mi wide at its widest point. It covers roughly 300 sq mi. Of its 260,000 acres, 20,000 acres consist of open water, 10,000 acres are marsh, 70,000 acres are swamp; and more than 85,000 acres are bottomland forest. It drains an area of about 44,000 sq miles, which includes 64% of Alabama and small portions of Georgia and Mississippi.