Work plan for regional reconnaissance for selected herbicides and nitrate in ground water of the mid-continent United States, 1991

An approach was developed to obtain a consistent, regional distribution of herbicide and nitrate data from near-surface aquifers in the corn and soybean producing region of the mid-continent. Near-surface aquifers are defined as those with the top of aquifer material within 50 feet of land surface, regardless of whether the material is saturated or unsaturated. Three hundred wells will be selected for sampling from 12 states. These States include Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin. The reconnaissance data obtained will be used to determine the spatial and seasonal distribution of selected herbicides, two atrazine metabolites, and nitrate in near-surface aquifers in the study region. Hydrologic, geologic, and land-use data will be collected for use in an exploratory statistical analysis to help explain the herbicide distribution.