Wing dikes are rock structures extending from the river bank perpendicular to the river's current. The Corps built them to prevent the main channel from filling by directing the river's current away from the bank and into the channel.
L Dikes or also called Trail Dikes are constructed along outside bends of the channelized Missouri River, trail dikes are positioned to protect against bank erosion. Similar to wing dikes, trail dikes provide rock habitat and deep holes, which attract many fish species.
As water is forced around and over a wing dike, it carves deep "scour holes" at the tip and downstream of the dike. The holes provide important winter and summer habitat for flathead catfish, blue catfish and channel catfish. The rocks of a wing dike also provide spawning and rearing habitat for catfish. Other big river fishes, such as carp, walleye, bluegill and largemouth bass, use the rock as shelter to avoid the constant force of the river's current.