Forecasting Water Demands and Systems Capabilities

One feature of the 1968 Illinois Water Plan was concern with the condition and future capability of water systems in 1200 incorporated communities. It was necessary to determine the condition of each water facility, such as its present pumpage, the filter plant capacity, and the water source capacity. Projections of the water demands on each system to the year 1980, and on a county basis to 2020, were made by using population estimates. By developing a gallons per capita per day relationship from present pumpage and present population data, corresponding 1980 values could be computed by using the appropriate projected population data. The technique for presenting these data is shown in both graphical and formula form. In addition, table sand graphs are included to show various parameter relationships and how the large amount of data were assembled in order to display projections individually, by counties, and by river basins. This water resource planning approach has a potential for wide use beyond the area for which it was developed.