Donald A. Keefer, and Illinois State Geological Survey
A statewide dataset for evaluating the potential for contamination of shallow aquifers by pesticides and nitrate. The sources of this data set were published and digitized at 1:250,000; however, the soils map and depth to aquifer map (stack-unit map) were generated from source data mapped at 1:15,000 and 1:64,000, respectively. This aquifer sensitivity map was published at 1:500,000 (statewide map), and 1:250,000 (county maps). Nominal scale is 1:250,000. ISGS.