Trends in Ground-Water Levels in Wisconsin, 1967-71 Supplement to Information Circular 9, Trends in Ground-Water Levels in Wisconsin through 1966. Climate and Weather Groundwater Data and Resources IC21 Trends in Ground-Water Levels in Wisconsin, 1967-71 Erickson, R.M.; 1972 Report: 40 p. Download Related Collections Information Circular View Information Circular