It was not dredging. It was a sophisticated structure to connect two distinct bodies of water. Per the article > "in its heyday it would have stretched a little

It was not dredging. It was a sophisticated structure to connect two distinct bodies of water. Per the article > "in its heyday it would have stretched a little less than a mile across most of Fort Morgan Peninsula, from Oyster Bay in the north to Little Lagoon in the south. Both bodies of water are at sea level, but the land between reaches up to six feet in elevation. That means anyone digging a trench across the peninsula would risk draining the water table into those sea-level outlets. The solution in this case may have been two dams at either end of the passageway that canoe travelers would have had to carry their boats around. With a shallow draft, dugout canoes would have only needed a few inches of water to pass through the three-foot-deep canal."