Developing Wetlands

Many areas in Missouri could be developed into productive wetlands with little expense. In fact, many wetland areas need only be identified, preserved, and protected. In such cases there is no development cost.

Before selecting the final site, consult an experienced wetland developer. MDC personnel can inform you of any restrictions or permits that might be required before construction begins. They will also be aware of any cost-share programs that might be available.

As a landowner, your first consideration should be your overall objective for the wetland and whether your property's potential site can meet your expectations. For example, if your objective is to benefit migrating waterfowl and to provide hunting opportunities, design and manage your wetland to provide seasonally available (fall and early spring) water and a sufficient quantity and quality of food to attract waterfowl. This usually requires a water-control system. However, if the wetland will be used mainly for water filtration, natural flooding will accomplish this objective.

Site Selection

Site selection is critical. The topography, soil type, water source, and overall objective for the wetland will influence the final site selection. The topography, or lay of the land, should be flat enough to allow shallow flooding of an area large enough to be functional. The soil must have the capacity to hold water.

Areas within floodplains along the base of hills, historic abandoned channels within the floodplain, back swamp areas along rivers, and areas below ponds or lakes can all provide excellent water sources. Often, extremely wet areas in fields occur in these locations and can be converted back to wildlife-beneficial wetlands. If floods ruin the crops in an area five out of 10 years, it may be better to eliminate this income risk by restoring the area to a wetland.

A good water source at the site is a very important consideration because a wetland cannot function without water. Your intended use of the wetland will dictate the quantity of water needed and the timing of delivery. The water can come from underground sources, such as wells or springs, or from ponds, lakes, or streams. Pumping water from underground sources can be expensive but will usually provide dependable water levels. If the water comes from natural sources or intermittent flooding, flood frequency and flooding heights of the adjacent stream must be considered.

Wetland Construction

Once you have selected an appropriate site, you can begin developing your wetland. Some wetlands may only require repair of natural levees, but others may need more extensive levee construction. Determine levee design by how you intend to use the wetland and site topography.

Levees should be built to a height of at least 12 inches above the maximum water line. This amount of “freeboard” will keep wave action and water saturation from destroying your levees. Too much freeboard may result in managed water levels that are too deep to benefit many wetland species. Usually a 6:1 slope is adequate on small levees. If the levee will be subjected to overtopping by floodwaters, an 8:1 or even 10:1 slope with a minimum 10-foot top should be used. The levee should be wide enough to allow maintenance of the top and side slopes. Flatter slopes on the levee will prevent damage from burrowing animals. Levees should be constructed away from stream banks to reduce erosion.

The type of water-level control device you install will be influenced by the intended use of the wetland and by the water source. A water-control structure typically consists of a culvert and a gate device to stop the flow of water. Various types of gates are available. Choose one to fit your specific situation.

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