Data for over 100 watershed properties, including aspects of topography, hydrology, geology, soils, vegetation, lake morphometry and input precipitation chemistry, have been developed since 1980 for 316 watersheds in northern Wisconsin. The hypothesis being evaluated for this lake population is that the observed water chemistry, can be accounted for as a function of antecedent water and chemical inputs, after considering exchange processes in the lake and watershed and the lake/groundwater interactions. Observed variability in color, sulfate, and acid neutralizing capacity levels in Wisconsin lakes were explained. The results differ from previous studies in Wisconsin and nearby areas of Michigan and Minnesota by indicating that in some lakes acidity may not be in equilibrium with current precipitation chemistry. (Copyright (c) 1986 by D. Reidel Publishing Company.)