LONG-TERM PUBLIC WATER SUPPLY WITHDRAWALS IN THE GREAT LAKES BASIN

The paper presents an update of long-term 2010-2050 estimates of municipal and industrial (M&I) water demand in the U.S. counties of the eight states in the Great Lakes Basin. The study area consists of 110 U.S. counties which are “adjacent” to the Great Lakes. The analysis of future demands employs the previously estimated water-use relationships in six Midwestern states in order to re-estimate future M&I water withdrawals and consumptive use.

The regression models of water withdrawals were estimated from the county level historical data on public-supply water use and its correlates, which included summer season precipitation, average summer temperature, per capita income, employment and housing. A time trend variable was used to capture the effect of water conservation during the historical period 1985-2000. The elasticities and parameters estimated from the historical data were used to prepare estimates of future water withdrawals for two scenarios: one with continuation of the recent historical conservation trends and another without continuing the conservation trend. For each of the two scenarios a sensitivity analysis was performed with respect to future climate (air temperature and precipitation) within the range of climate variability specified as an increase in air temperature by 6ºF and precipitation shifts within ±5 inches, both to 2050 period.