[1] Univ Minnesota, Water Resources Sci Program, Minneapolis, MN 55455 USA
[2] Univ Toronto Scarborough, Dept Phys & Environm Sci, Toronto, ON, Canada
[3] Sci Museum Minnesota, St Croix Watershed Res Stn, St Paul, MN USA
[4] Minnesota Dept Nat Resources, Div Lands & Minerals, St Paul, MN USA
[5] Univ Minnesota Duluth, Dept Civil Engn, Duluth, MN 55812 USA
[6] Univ Wisconsin, Plant & Earth Sci, River Falls, WI 54022 USA