Out walking with a short lens.
Both photographs feature the trunks used to control the depth and flow of water across all these marshes. Initially the first trunk is opened on a dike near a salt marsh. Fresh water is lighter than salt and only the top of the truck allows fresh only to flow.
Other trunks on dikes are opened to allow the flow between each marsh, a chain of open gates for fresh water.
The wooden dikes are the same methods used for several hundred years. People enslaved from Barbados and West Africa first introduced this system in the early 1700’s.
ACE Basin, South Carolina.