The U.S. Geological Survey, in cooperation with the Kentucky Natural Resources and Environmental Protection Cabinet, constructed a two-dimensional, steady-state ground-waterflow model to estimate hydraulic properties, contributing areas to discharge boundaries, and the average linear velocity at selected locations in an aquifer system near Calvert City, Ky. Nonlinear regression was used to estimate values of model parameters and their reliability. The regression minimizes the weighted difference between observed and calculated hydraulic heads and rates of flow. The calibrated model generally was better than alternative models considered, and although adding transmissive faults in the bedrock produced a slightly better model, fault transmissivity was not estimated reliably. The average transmissivity of the aquifer was 20,000 feet squared per day. Estimated recharge to two outcrop areas, the Cretaceous McNairy Formation and the Quaternary alluvium, was 0.00269 feet per day (11.8 inches per year) and 0.000484 feet per day (2.1 inches per year), respectively. Contributing areas to wells at the Calvert City Water Company in 1992 did not include the Calvert City Industrial Complex. Since completing the field work for this study in 1992, the Calvert City Water Company discontinued use of its wells and began withdrawing water from new wells that were located 4.5 miles east-southeast of the previous location; the contributing area for these new wells moved farther from the industrial complex. The extent of the alluvium contributing water to wells was limited by the overlying lacustrine deposits. The average linear groundwater velocity at the industrial complex ranged from 0.90 to 4.47 feet per day with a mean of 1.98 feet per day.

Approximate locations of the long-term rainfall station, evaporation stations, and the rural streamflow-gaging stations in Kentucky and Indiana, used in the study...... 7 Contents III 3-7. Graphs showing: 3. Comparison of observed and simulated peak discharges at selected sites and all sites combined for storms used in calibrations of the Rainfall-Runoff Model (RRM)