Poster Presentation C Thursday, 5:00 6:00 pm C Edmund Fitzgerald Exhibit Hall

Minnesota Lake Water Clarity

Leif Olmanson, Marvin Bauer
University of Minnesota
Department of Forest Resources
Remote Sensing and Geospatial Analysis Laboratory
115 Green Hall
1530 Cleveland Avenue North
St. Paul, MN  55108

Patrick Brezonik
University of Minnesota
Water Resources Center
173 McNeal Hall
1985 Buford Avenue
St. Paul, MN  55108

Based on a strong relationship between Secchi disk transparency and spectral-radiometric responses in Landsat TM bands 1 and 3 we have developed an image processing and classification protocol for assessment of lake water clarity. The procedures have been successfully used to classify the water clarity of over 10,000 lakes using 15 early 1990s Landsat TM scenes that cover the entire state of Minnesota. The resulting map gives a regional view of water clarity over the entire State of Minnesota. The map indicates that there are more eutrophic lakes in the southern and southwestern parts of State to more oligotrophic and mesotrophic lakes in the northern and northeastern parts of the State. Minnesota lake water clarity distribution and swimming use support information is also presented. The results indicate that satellite remote sensing is a cost effective way to gather information needed for water quality assessments in lake-rich areas like Minnesota.