This description of prairie basin wetlands of the Dakotas is part of a series of community profiles on ecologically important wetlands of national significance. The shallow wetlands of the Dakotas form the bulk of the portion of the Prairie Pothole Region lying within the United States. This region is famous as the producer of at least half of North America's waterfowl and an unknown, but large, proportion of other prairie-dwelling marsh and aquatic birds.The wetlands described here lie in relatively small, shallow basins that vary greatly in their ability to maintain surface water, and in their water chemistry, which varies from fresh to hypersaline. These wetlands occur in a wide variety of hydrological settings, in an area where annual and seasonal precipitation varies greatly in form and amount. Thus the presence of surface water in these wetlands is largely unpredictable. Superimposed on these phenomena are the effects of a variety of land uses, including pasture, cultivation, mechanical forage removal, idle conditions and burning. All those factors greatly affect the plant and animal communities found in these basins.This profile covers lacustrine and palustrine basins with temporarily flooded, seasonally flooded, and semipermanently flooded water regimes. Basins with these water regimes compose about 90% of the basins in the Prairie Pothole Region of the Dakotas. This profile outlines the wetland subsystems, classes and subclasses that occur in these basins, and provides a useful reference to their geologic, climatic, hydrologic, and pedologic setting.Detailed information on the biotic environment of the wetlands dealt with in this profile will be useful to scientists and resource managers. Special recognition is paid to the macrophyte and invertebrate communities, which have dynamic qualities found in few other of the world's wetland ecosystems.The most noteworthy animal inhabitants of these basins are waterfowl, which are a resource of international concern. Because of the importance of this resource, much research on the habitat use and feeding ecology of breeding waterfowl has been conducted in the region. These topics receive special attention in this profile.The Prairie Pothole Region is a major world supplier of cereal grains. Consequently, wetlands in the region are often drained for crop production or otherwise cropped when water conditions permit. These practices degrade the value of wetlands for most species of wildlife and conflict with the aims of conservationists. The subject of human uses and impacts to prairie wetlands is thus an important part of this profile.