TRANSPARENCY CALIBRATIONS FOR LAKE ST CLAIR AND LAKE-MICHIGAN

Extensive measurements of water transparency using a Sea Tech transmissometer and total suspended solids (TSM) were made in the southern basin of Lake Michigan and in Lake St. Clair. The relationship between transparency and TSM in each lake can be expressed very well by a single equation. The similarity in the slopes of the lines for the two lakes suggests that the physical properties of the particles suspended in the water are very similar, while the large difference between the intercepts is due to the presence in Lake St. Clair of very fine material (particle diameter less than one micron) which is not present in Lake Michigan. Attempts to use the transparency measurements to identify different particle populations in Lake Michigan as a function of time, station, and sample depth were unsuccessful. Limited data from northern Lake Michigan, Lake Huron, and Lake Superior suggest that the material in Lake Huron is similar to that in the southern basin of Lake Michigan while the observations in northern Lake Michigan more closely resemble those from Lake Superior. © 1990, International Association for Great Lakes Research. All rights reserved.