1. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin, USA; e-mail: , mbrey@usgs.gov, rerickson@usgs.gov, afritts@usgs.gov, bknights@usgs.gov, gsaari@usgs.gov
2. U.S. Geological Survey, Columbia Environmental Research Center, Columbia, Missouri, USA; e-mail: , ageorge@usgs.gov, dchapman@usgs.gov, jessefischer@usgs.gov
3. U.S. Geological Survey, Central Midwest Water Science Center, Urbana, Illinois, USA; e-mail:
4. U.S. Geological Survey, Ecosystems Mission Area, Reston, Virginia; e-mail: