Wet prairies covered a much smaller proportion of the unit than in the Minnesota River Prairie. Wet prairie was restricted to narrow stream margins. Forest was similarly restricted to ravines along a few streams, such as the Rock and Redwood rivers. There are few remnants of presettlement vegetation left. Fires were very common before settlement, re-energizing the prairie plant communities.
Tornadic events associated with thunderstorms are also common.
The major conservation concern is water quality. Shallow aquifers which used to supply the rural population with water are now polluted with nitrates, phosphates and pesticides. Agricultural activity is the major source of this pollution. Presently, there are rural water associations providing much of the water for rural people. The source of this water is deep wells that tap into the Dakota Aquifer.