Through enhancement and active management healthy, clear water wetland conditions can be achieved. State of the art fish barriers and water control structures installed on inlets and outlets to shallow lakes and large marshes effectively restore and maintain water quality and abundant aquatic food resources for lesser scaup, mallards and other waterfowl species. Ducks Unlimited engineers have led the way to healthy wetland systems with innovative structural designs and cost effective techniques.
Water control structures allow wetland managers the ability to raise and lower water levels within the marsh or shallow lake to stimulate a desirable vegetation response or reduce rough fish populations. Lowering lake levels by just a few feet during the fall may be enough to encourage a winterkill of fish. Fully draining a lake consolidates basin sediments and encourages growth of desirable plants. In both cases, a lake returns to a healthy, clear water state and aquatic plant and invertebrate populations rebound.
Fish barriers, as the name suggests, are engineered devices designed to prevent nuisance fish from entering a water body. Fish barriers are placed on the inlets and outlets of shallow lakes and marshes where fish enter the wetland from feeder streams and ditches. Water passes through the structure, but fish are prevented from passing. Below are two styles of fish barriers employed by DU. The fish barrier is a finger style fish barrier designed to prevent larger fish from passing upstream through the fingers while allowing water to pass freely through the barrier. The second fish barrier is a more complicated design developed by DU engineers that prevents all sizes of rough fish from moving into a shallow lake.
Wild Rice Lake Management in Minnesota
DU is focused on managing key wild rice lakes in the forested region of northern Minnesota. Wild rice provides both food and cover for waterfowl, and these lakes are important breeding and fall staging areas, especially for ring-necked ducks, wood ducks and mallards. Beaver dams, cattail mats and sediment in the outlets of these lakes can raise water levels and drown out wild rice. DU is working to eliminate these obstructions and maintain free flowing outlets.