|Lerch, Robert - Bob|
Submitted to: National Cave and Karst Management Symposium
Publication Type: Abstract only
Publication Acceptance Date: 4/26/2007
Publication Date: 10/8/2007
Citation: Lerch, R.N., Kremer, R.J. 2007. Fecal bacterial contamination of a karst watershed in central missouri. Available: http://www.nckms2007.org/program/abstracts.html. National Cave and Karst Management Symposium, October 8-12, 2007, St. Louis, MO. Interpretive Summary:
Technical Abstract: The Bonne Femme watershed of Boone County, Missouri has a varied surface geology that includes karst topography with losing streams that are an especially vulnerable setting for ground water contamination. The study objective was to compare fecal contamination and detection of specific pathogenic water-borne bacteria within the major sub-watersheds and relate this contamination to land-use and hydrology. Ten sub-watersheds (8 surface and 2 sub-surface) were sampled weekly, for one month per quarter-calendar year since 2003 for fecal coliforms, Escherichia coli, enterohemorrhagic E. coli O157:H7, Salmonella, and Shigella. Fecal coliform and E. coli enumeration were done by the membrane filtration techniques, and pathogen specific analyses were performed through culture enrichment of water samples followed by DNA extraction of bacterial growth and PCR using pathogen-specific primers. Under low-flow conditions, fecal coliforms and E. coli levels were typically less than 1000 cfu/100 mL, but many sites exceeded state and federal whole body contact limits in the 2nd and 3rd quarters of the year. Under high flow conditions, most sites exceed 10,000 cfu/100 mL, and whole body contact limits were always exceeded. Salmonella and Shigella were detected in at least two streams in each quarter of 2005 and 2006; E. coli O157:H7 was detected in at least one stream each quarter since 2nd quarter 2005. In general, fecal bacterial contamination was significantly correlated to stream discharge and time of year, but it was not significantly correlated to land cover or to physico-chemical properties of the stream water within the sub-watersheds. Site specific causes explained the observed levels at the three sites with the highest fecal bacterial contamination.