Using Hydrologic Tracers as a Risk Assessment Tool in a Karstic Watershed

Watershed studies using a variety of observational parameters are being implemented to assess how pathogen indicators migrate through rural watersheds. The objectives of the research are to examine the presence and persistence of Bacteriodes and E. coli in several east Tennessee watersheds through observations made in the main channel. Evaluation of combined surface water and groundwater inputs should be evaluated when considering possible regulatory actions through establishment of total maximum daily loads. Further, correlations between hydrologic parameters, water quality, Bacteriodes, and E. coli. are being evaluated in order to examine watershed processes in the system and determine their behavioral response to watershed practices and hydrologic stresses. The experimental design includes a preliminary synoptic evaluation of the water chemistry and bacteria during baseflow conditions through repeated measurements. Streams are known to gain and lose flow throughout the watershed, with certain areas being in proximity to karst features. Definitive causation of bacteria at baseflow is speculative at this point. Sinkhole topography is hypothesized to play an important role in the occurrence of bacteria in the channel which may provide rapid hydrologic transport to and from the channel on a seasonal basis, although direct observation from sinkholes and springs have not been made at this point in the study. The study will provide a robust dataset for evaluating landuse input functions for hydrologic inputs to the watershed.