CONSUMPTIVE WATER-USE COEFFICIENTS IN THE GREAT LAKES BASIN

Water-resources managers and planners in the Great Lakes Basin are developing policies for optimizing water use and reuse in the face of increasing demand. To that end, Great Lakes agencies are interested in refining consumptive-use data and increasing their knowledge of estimating coefficients. Consumptive use is water that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate environment. Consumptive use commonly is computed by means of water-balance equations or by application of consumptive-use coefficients (generally, the ratio of consumption rate or volume to withdrawal rate or volume). Because detailed data are needed to use a water-balance equation, consumptive use frequently is estimated with coefficients.

As part of the Great Lakes Water Availability and Use Program, the U.S. Geological Survey compiled and analyzed consumptive water use data and coefficients from more than 100 documents on for the Great Lakes Basin, climatically similar areas in the United States, and elsewhere in the world. These consumptive-use data and coefficients were compiled by water-use categories (domestic and public supply, industrial, industrial use by major standard industrial classification code, thermoelectric power, irrigation, livestock, commercial, and mining) and published in a report. The purpose of the report was to determine (1) what data and coefficients were available, (2) what methods and data used to calculate consumptive use, (3) the range of coefficients reported within water-use categories, and (4) the degree to which the coefficients for the Great Lakes Basin and climatically similar areas compare to each other and to coefficients determined for other areas of the world. This compilation of all these consumptive-use data and coefficients can serve as a starting point for facility managers, water managers, and scientists who wish to estimate water consumption.