1. North Carolina State University, Raleigh, North Carolina, USA
2. Iowa Geological Survey, Iowa City, Iowa, USA
3. The University of Iowa, Iowa City, Iowa, USA
4. Iowa Environmental Council, Des Moines, Iowa, USA
5. Toxic Substances Hydrology Program, U.S. Geological Survey, Iowa City, Iowa, USA
6. University Hygienic Laboratory, Iowa City, Iowa, USA