EVALUATING STATEWIDE AND REGIONAL GROUNDWATER QUALITY USING ARCHIVED DATA AND ONGOING MONITORING

The Kentucky Geological Survey and the Kentucky Division of Water are evaluating ambient (not affected by point-source discharges) groundwater quality statewide, within physiographic and geographic regions, and within major watersheds. Our goals are to determine the amounts and variability of inorganic solutes, nutrients, pesticides, and volatile organic chemicals in groundwater, and to investigate natural versus nonpoint-source controls on groundwater quality.

Data sources include the Kentucky Groundwater Data Repository, which contains analytical reports from more than 15,000 wells and springs, and an ongoing groundwater monitoring program, which samples more than 120 sites quarterly each year. Data tables and probability plots are used to summarize solute concentrations statewide, within physiographic regions, and within major watersheds. Maps are used to show relations of concentrations to bedrock type and land use. Box-and-whisker plots are used to compare concentrations in different physiographic regions and different watersheds, and to compare concentrations from springs versus wells and filtered versus unfiltered samples. Plots of concentrations versus well depth are used to compare solute abundances in shallow, intermediate, and deep flow systems.

Results show that concentrations of most inorganic solutes, including metals, are controlled by bedrock lithology. Some springs and shallow wells have exceptionally high levels of nutrients and detectable amounts of pesticides, indicating that nonpoint-source chemicals have entered the groundwater system. Volatile organic chemicals are only rarely present in amounts above analytical detection limits. These results are being used to refine groundwater protection programs and help make informed decisions regarding groundwater use.