We are from a river area that is similar to the ICW. Our delta contains thousands of miles of creeks and sloughs, and a dredged ship channel from San Francisco to Stockton, our hometown.
This wetland area probably looked a lot like the ICW two hundred years ago, but around 1930 peatland islands were reclaimed from the river by building levees. (Some say these "islands" should be called polders, and these "levees" should be called dikes, but that a whole 'nother discussion.)
This rich reclaimed soil was used for farmland with thousands of acres under cultivation in tomatoes, corn, sunflowers, and the Queen of our Delta, asparagus. By the way, there is no asparagus in the world that can compare with the asparagus grown in that peaty soil.