Georgia Water Science Center
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The Apalachicola-Chattahoochee-Flint (ACF) River National Water Quality Assessment (NAWQA) Program
ACF Study Design: Special Studies
The study design for the ACF River basin study unit was modified to include four special studies: 1) addition of an intensive network of synoptic sites within the poultry, urban and suburban basins; 2) analysis of sediment cores collected from six of the reservoirs within the study unit; 3) intensive sampling of the Flint River during record flooding; and 4) seasonal sampling of fish to determine community recovery following the record flooding. Each of these activities was pertinent to the assessment of water-quality conditions within the ACF River basin, and also provided information of value to both regional and national synthesis efforts.
A network of surface-water monitoring sites, which included the poultry indicator site, three-between basin comparison sites, and seven additional sites, were sampled during a two-day synoptic survey that represented baseflow conditions in the upper Piedmont region of the ACF River basin. Three surveys were conducted within Sope Creek which included the indicator and within basin comparison sites and an additional twelve sites located within the Sope Creek basin. Two surveys were conducted within the metro Atlanta area. Eleven sites were sampled in May 1995. The second survey, conducted during July 1995, was expanded to include 39 sites within metropolitian Atlanta and Columbus, including integrator, indicator, comparison, large tributaries, two additional mainstem sites, and 19 sites located within the Peachtree Creek basin. The purpose for these surveys was to locate areas of ground-water discharge that would provide the basis for a flow-system study, and to better define water quality in small basins affected by urban and suburban land uses. On-site measurements of flow and field parameters were made, and samples were collected and analyzed for nutrients, pesticides, major ions, and organic carbon.
The system of reservoirs within the study unit provided an opportunity to evaluate land-use changes and chemical inputs within the basin, as reflected by changes in the chemical composition of sediments deposited within the reservoirs. Sediment cores were collected from six of the major reservoirs for the purpose of defining changes within each reservoir and differences between reservoirs. Each core was divided into discrete subsamples that were age dated and analyzed for a suite of organic compounds, trace metals, major ions, nitrogen, phosphorus, and carbon.
During July 1994, Tropical Storm Alberto caused record flooding in southwestern and central Georgia, southeastern Alabama, and northwestern Florida. Parts of Georgia received as much as 28 inches of rainfall during the storm. The record flooding provided a unique opportunity to measure concentrations and loads of nutrients, suspended sediments, and pesticides during extreme hydrologic conditions. Water samples were collected from several locations affected by the flood, but the most frequent data collection within the ACF River basin occurred at the Flint River at Newton, Georgia, the most downstream site that was accessible throughout the flood. Nineteen samples were collected during the period July 5-26, 1994.
The record flooding also provided an opportunity to document the recovery of fish communities following the catastrophic event. The pre-flood fish community in Lime Creek, one of six indicator sites, had been documented as a part of the original study design based on samples collected in June 1993 and May 1994. To determine post-flood community structure three samples were collected during the period August 1994 through August 1995.