Escherichia coli in the swash zone at four Ohio bathing beaches

The zone of the shoreline that is constantly washed by waves or tides, called the swash zone, is an attractive recreational area, especially for children who play in the sand. The swash zone, however, has been suggested as a possible habitat for waterborne disease-causing microorganisms (pathogens). The spaces between the sand grains, or interstices, offer habitats that may support the survival of certain bacterial, viral, and protozoan pathogens (U.S. Environmental Protection Agency, 1999). To investigate this possibility, the U.S. Geological Survey (USGS) determined the distribution of Escherichia coli ( E. coli ) in subsurface sediments and interstitial waters collected from near the swash zone at three Lake Erie urban beaches and one inland lake during the recreational seasons of 2000 and 2001. Water and lake-bottom sediment samples were also collected within the bathing areas and were analyzed for E. coli ; these bathing-water data were compared to swash-zone data to determine whether swash-zone materials were enriched with E. coli .