Concentration of chemical constituents in lake sediments from selected coring locations on Lake Lanier, Georgia, May 2018

The data herein were collected in support of a larger study in Gwinnett County, Georgia, on the potential impacts of on-site waste water treatment (septic systems) on Lake Lanier water quality. Until recently, a missing component in this assessment was the inclusion of historical sediment and associated nutrient accumulation data from the lake to place results in a broader context. To this end, the USGS collected sediment cores from ten locations that varied in water depth as well as proximity to residential areas with septic systems. Samples were collected using either a gravity corer or box corer depending on site conditions. Cores were sub-sampled and processed for laboratory analyses. Laboratory analyses were conducted to evaluate nutrient concentrations (carbon, nitrogen, and phosphorus) in sediments, stable isotope ratios of carbon and nitrogen in the sediment organic matter, cesium-137 for select samples, and trace and heavy metals. The latter constituents (cesium-137 and trace and heavy metals) were used primarily to help constrain mass accumulations rates (MAR) and assign ages to each sub-sample so that temporal changes in nutrient concentrations could be evaluated in concert with timing of shoreline development.