1. Dep. of Epidemiology; Univ. of Washington; 1959 NE Pacific Street, Health Sciences Building F-262, Box 357236 Seattle WA 98195
2. Dep. of Civil Engineering; Univ. of Nebraska-Lincoln; N104 SLNK Lincoln NE 68588
3. Dep. of Civil Engineering; Univ. of Nebraska-Lincoln, 203B Peter Kiewit Institute; Omaha NE 68182
4. Environment Dep.; Univ. of York; Heslington York YO10 5DD UK
5. Agroecosystem Management Research Unit, USDA-ARS; 137 Keim Hall, UNL-East Campus Lincoln NE 68583
6. Water Resources Research Center; Univ. of Arizona; 350 N Campbell Avenue Tucson AZ 85719
7. Dep. of Veterinary and Biomedical Sciences; Univ. of Minnesota; 1971 Commonwealth Avenue St. Paul MN 55108
8. Water Sciences Laboratory; Univ. of Nebraska-Lincoln; 202 Water Sciences Laboratory, 1840 North 37th Street Lincoln NE 68583
9. Dep. of Civil and Environmental Engineering; Univ. of Illinois at Urbana-Champaign; Urbana IL 61801