Results from a Source Tracking Assessment of a Nutrient-polluted Watershed

A study conducted by in 2006 sought to characterize a watershed and determine whether the influences of cattle best management practices could be detected at the watershed scale. The Brushy Creek watershed in southeastern Kentucky was monitored for physical and chemical water quality parameters throughout at 18 surface water and six groundwater sites. GIS was then used to compare areas of the watershed with high adoption of cattle BMPs with areas of sparse or non-adoption. The results indicated no differences in water quality that could be attributed to the presence or absence of the BMPs. The suggested hypothesis was that the karstic nature of the watershed was not considered in the development of the BMPs. The current study slated for completion in the spring of 2011, seeks to determine whether karstic groundwater-surface water interaction adequately explains why the cattle BMPs have had little effect on water quality. To date, the land and hydrological conditions of the area have been characterized, including land use groundwater movement, physical habitat assessment of riparian corridors, and censuses of fish and invertebrates. Preliminary results comparing areas of the watershed where groundwatersurface water interactions are high suggest that groundwater is a substantial conduit of nutrient and E. coli contaminants in the stream network. All sites show some form of coliform bacteria. qPCR analysis currently under way indicates that cattle is the predominant source of bacterial contamination, although several sites do appear to have human bacteria as a minor contamination source (less that 10%). Analysis in progress includes source tracking to determine the percentage of bacterial contamination contributed by bovine sources. Seasonally spaced sampling is planned for all sites to allow for comparison with previous analysis. In addition, two sediment samplers are being deployed to characterize movement of suspended solids and particulates through the system.