1. Water Bacteriology Department, Wisconsin State Laboratory of Hygiene, 2601 Agriculture Dr., P.O. Box 7996, Madison, WI 53707-7996, USA
2. Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 600 N. Park Street, Madison, WI USA
3. Environmental Health, Department – Water Bacteriology, Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, 2601 Agriculture Drive, Madison, WI 53718, USA