1. The Conservation Fund Freshwater Institute, 1098 Turner Road, Shepherdstown, WV 25543, USA
2. Bureau of Science Services, Wisconsin Department of Natural Resources, 2801 Progress Rd, Madison, WI 53716, USA
3. Department of Natural Resources Ecology and Management, Iowa State University, 339 Science II, Ames, IA 50011, USA
4. Department of Agricultural and Biosystems Engineering, Iowa State University, 100 Davidson Hall, Ames, IA 50011, USA