Channel dredging created Cape Fear’s spoil islands

The N.C. State Port in Wilmington is 24 miles upriver from the mouth of the Cape Fear River. A channel is maintained to allow large ships to travel upriver to the port. There is almost continual maintenance dredging at some point between the river’s mouth and Wilmington.

Dredging removes large quantities of dirt, mud, rock, debris, former ballast stone and other things from the bottom of the river. While there are a few areas to store this detritus along the river’s banks — some has been carried to offshore spoil areas — there are many islands in the river along the edge of the channel that were formed with this material; they are collectively called spoil islands. Initially, these islands were bare mounds of sand, mud, rock and other debris, but over time, they have developed vegetation and become home to birds and wildlife. The sandbars, marshes, flats and ledges around them have become havens for fish.

Spoil islands are constantly changing and shifting, so the number isn’t constant. At any time, there are about 20 spoil islands in the river between Wilmington and the ocean, some very small and some quite large. Some have large, diked spoil containment areas, some are barely above water and most are at numerous stages of building and/or erosion.

A spokesman for the U.S. Army Corps of Engineers said about half are under their control for spoil-containment sites from easements given by the state in 1965. The others are state and privately owned.

In their simplest form, the spoil islands are obstacles adjacent to the deep channel that interrupt the tidal currents in the river. Many of the older ones have developed ecosystems that include trees and land grasses above the high-water level, plus flats, drop-offs and marsh grasses in the water. Some of the joined islands have small creeks running into them where they were once separated. This creates a diverse habitat for baitfish, shrimp and larger predators.

Fishermen using shallow-draft boats and kayaks exploring the flats and marshes around the spoil islands have found they hold a wide variety of fish. Flounder, red drum and speckled trout are common catches, and they occasional hold stripers, gar, sturgeon and other species.