Watershed descriptors have been obtained or compiled for 1439 watersheds in the northeastern and upper midwestern United States. A methodology, which combines multiple linear regression procedures with a simple deterministic model for alkalinity shows promise as a tool for acid precipitation assessments. Mean absolute errors in predicted lake alkalinity concentrations of approximately + or - 100 micro eq/L were obtained with no significant difference (at the 0.05 significance level) between predicted and observed alkalinity histograms. Estimates of the lake resources-at-risk across the depositional gradient from Minnesota to the Adirondack Park of New York were established.