1. National Risk Management Research Laboratory, US Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268 USA
2. Humboldt State University, Department of Environmental and Natural Resource Sciences, 1 Harpst Street, Arcata, California 95521-8299 USA
3. Department of Resource Management and Geography, University of Melbourne, 221 Bouverie St. Parkville, Victoria 3010, Australia
4. River Basin Center, University of Georgia, 110 Riverbend Parkway, Athens, Georgia 30602 USA