Finally, a good photograph of a wooden ‘trunk’, or water gate. This particular one has just been added here.
The side we see is viewed from inside a marsh. The dike is the dirt wall which the long wooden box section has been inserted under. A trunk is simple a wooden box, open on both sides that water flows through. A gate, here the tall boards, with a solid wooden bottom can be pushed to close the open end and stop the flow of water.
The other side of this dike is the Ashley River which flows down to Charleston. Most dikes will have a trail on top, some even a dirt road. These marshes and dikes go for miles.
The holes visible in the center board allow a pole (new trunk here, so metal pipe) to be inserted and pushed up/down to control the wooden doors position. Basically open and close the hole and flow.
The trunk in this dike is the same as they were in the 1600’s, except the metal pipe of course. All through the entire South Carolina and Georgia Lowcountry there are thousands of these trunks still keeping water flowing in marshes.
The link at the start of this article is a great, and short, history of these marshes and trunks.