Georgia Water Science Center
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The Apalachicola-Chattahoochee-Flint (ACF) River National Water Quality Assessment (NAWQA) Program
ACF Study Design: Groundwater Study Unit Survey
The study-unit survey was designed to characterize the quality of shallow ground water within the Upper Floridan Aquifer System and to determine the effects of land use. An area of about 3,900 sq mi in the southern part of the study unit, known locally as the Dougherty Plain and Marianna Lowlands, and underlain by the Floridan aquifer system, was selected for the ground-water study-unit survey. The predominant land use in the Dougherty Plain and Marianna Lowlands is row-crop agriculture and orchards. The source of some public and most domestic water supply is the Floridan aquifer system, a highly productive fractured limestone aquifer having karst features. To establish sampling sites within the Dougherty Plain and Marianna Lowlands, the area was subdivided into 30 polygons of similar size and existing wells or, where present, one or two high-flow springs were chosen for sampling from each polygon. Forty two sites were selected for sampling. Depth to water in the monitoring wells ranged from 10-60 ft below land surface (one well was a flowing well with approximately 3 ft of head). Each site was sampled once in August or September 1995. Samples were analyzed for nutrients, pesticides, volatile organic compounds, trace metals, major ions, organic carbon, stable isotopes, and selected radionuclides. On-site measurements of ground-water levels, flow from springs, and field measurements were made at each site.