Small Impoundment Management in North America

Chapter 16: Managing Small Impoundments for Wildlife

Kevin D. Nelms, Michael D. Porter, and Matthew J. Gray


In addition to providing habitat for fish, small impoundments that are constructed and managed properly can attract and support various wildlife species. Managed impoundments are important water sources for wildlife and can provide food and cover necessary for survival and reproduction. This chapter introduces impoundment characteristics and management techniques that provide wildlife habitat. We also address management of major groups of wetland dependent wildlife that use impoundments.

Most wildlife need water for daily survival. Some species have adapted to and require water for their entire life cycle (Marks 2006). These species are called wetland dependent wildlife. At least 150 bird species in the USA are classified as wetland dependent (Marks 2006). Additionally, another 900 terrestrial wildlife species use wetlands for breeding, foraging, or other life cycle activities (Marks 2006). Impoundments that are managed properly can play an important role in providing habitat for wetland dependent species.

Most small impoundments provide deepwater habitat (>2 m in depth), but also create shallow flooded areas known as wetlands. Wetlands are areas where water covers the soil or is present near the surface of the soil for at least part of the year (Lewis 1995; Mitsch and Gosselink 2000; Marks 2005; Baldassarre and Bolen 2006). The presence of water and the subsequent lack of oxygen create particular types of soils called hydric soils (Lewis 1995; Mitsch and Gosselink 2000; Baldassarre and Bolen 2006; Marks 2006). Saturated soil conditions and impounded water in wetlands favor the growth of water-loving plants, called hydrophytes (Lewis 1995; Mitsch and Gosselink 2000; Marks 2005; Baldassarre and Bolen 2006).

Wetlands are responsible for producing and supporting many wildlife species, such as waterfowl, songbirds, shorebirds, reptiles, amphibians and some mammals. Wetlands provide habitat for one-third of the federally listed endangered and threatened plant and animal species (Marks 2006). Many wildlife species require a complex of wetlands to meet life cycle needs (Baldassarre and Bolen 2006; Marks 2006). For example, migratory waterfowl and shorebirds need wetlands at their breeding grounds located in the northern USA and Canada, but also need wetlands during migration, which can extend to Central and South America. Other species such as amphibians frequently disperse among wetlands, and their populations depend on this exchange of individuals to maintain genetic diversity. Thus, impoundments can provide important habitat for various wildlife across a landscape, and contribute to maintaining populations.