Biogeochemical Indicators of Land-Use Change in the Grand Traverse Bay Watershed

The USGS has a continuing collaboration with faculty at Michigan State University (MSU; David W. Hyndman and David T. Long, Department of Geological Sciences; Bryan C. Pijanowski, Department of Entomology) to relate land use and land use change to water quality in the Grand Traverse Bay Watershed, MI. The USGS component of this collaboration addresses how land use affects the occurrence and distribution of E. coli bacteria, chemical indicators of human pollution such as caffeine and cholesterol, and recently, the presence of specific pharmaceutical compounds. In collaboration with MSU , the USGS has (1) sampled up to 35 sites for coliform and E. coli bacteria on 7 dates over four years; (2) analyzed the DNA fingerprints of 335 E. coli bacteria taken from these sites and antibiotic resistance patterns for 95 of these, and shown relations between land use and sampling date and the types of E. coli found; (3) evaluated sampling methodologies and spatial scales required for optimum E. coli DNA fingerprint detection; and (4) detected indicators of pharmaceutical compounds (caffeine, cholesterol, nonylphenols, plus other constituents) at selected watershed sites on multiple dates. We have recently begun to incorporate this information into GIS and hydrologic models developed by our MSU collaborators.

In addition, at the request of the Grand Traverse County Public Health Department, we have recently sampled water and sediments at county beaches to provide background information on microbial pollution at these sites, using new methods proposed for beach monitoring by the USEPA. This prior and current work allows us to relate microbial and emerging-contaminant pollution of waters in the Grand Traverse Bay Waterhsed to (1) land use, (2) possible source and (3) hydrologic conditions and to predict trends in these parameters as land use changes occur.