1. U.S. Geological
Survey, 2280 Woodale Drive, Mounds View, Minnesota 55112, United States
2. University of Wisconsin−La Crosse, River Studies
Center, La Crosse, Wisconsin 54601, United States
3. National Atmospheric
Deposition Program, Illinois State Water Survey, University of Illinois, 2204 Griffith Drive, Champaign, Illinois 61820, United States
4. National Park
Service, Voyageurs National Park, 415
South Pokegama Avenue, Grand Rapids, Minnesota 55744, United States
5. U.S. Geological
Survey, 8505 Research Way, Middleton, Wisconsin 53562, United States