The tills in the eastern Dakotas tend to be much higher in shale-derived material. Because prairie wetlands are characteristically nonintegrated, ground-water flow systems play a dominant role in their hydrologies. LaBaugh et al. LaBaugh et al. Through-flow basins hold water over longer periods and the water tends to have higher concentrations of dissolved solids.
Some basins serve only as discharge areas for ground water.
Wetland hydrologic functions control the chemical characteristics of prairie lakes, and as a result, plant and invertebrate communities.