As water moves through the limestone, shale, and sandstone geologic formations underlying Crawford County, it dissolves and carries in solution minerals contained in the bedrock. Iron and hydrogen sulfide are contaminants of wells particularly in the central part of the county. Human activities, such as agricultural production, domestic waste disposal, and lawn and turf care, may have some influence on the county's ground-water quality. This range is assumed to represent natural background levels. The average test value for the 114 wells tested was 1.52 ppm.
Bacterial counts are another indicator of ground-water quality.
The Crawford County Department of Health tests water samples for concerned citizens. Results of these tests indicate an occasional fecal coliform well contamination in wells. Design, location and condition of a well, as well as the characteristics of the soils and geologic formations in which the well is constructed, influence the potential for pollutants to enter the well. Surface Water Runoff and sediment from residential development, construction sites and agricultural lands may enter the county's streams and lakes. Crawford County contains portions of several streams and their tributaries that have been classified by the Assessment as being affected by nonpoint source pollution.