Estimates of water demand in the Kankakee River Water Supply Planning Subregion were developed for the period 2010 to 2060. The estimates were developed separately for five major water demand sectors: (1) public supply; (2) self-supplied domestic; (3) self-supplied thermoelectric power generation; (4) self-supplied industrial and commercial; and (5) self-supplied irrigation, livestock, and environmental. Estimates were developed for all sectors on a county level and for public supply at a facility level for 12 dominant public systems, including the largest systems in each county. The techniques used to develop estimates differed by sector and included unit-demand methods and multiple regressions. These methods provided estimates of future demand as a function of demand drivers and explanatory variables for many sectors and subsectors. Explanatory variables are those that influence unit rates of water demand, such as summer-season temperature and precipitation, median household income, marginal price of water, employment-to-population ratio, labor productivity, and precipitation deficits during the irrigation season. For most sectors and subsectors, total demand was estimated by multiplying unit rates of water demand by demand drivers. Demand drivers included such measures as population served by public systems, population served by domestic wells, number of employees, gross thermoelectric power generation, irrigated cropland acreage, irrigated golf course acreage, and head counts of various livestock types. For each sector, three scenarios were developed of future water demand that reflect different sets of plausible socioeconomic and weather conditions. These include a less resource intensive (LRI) scenario, a current trends (CT) (or baseline) scenario, and a more resource intensive (MRI) scenario. A “normal” climate, based on 1981-2010 climate “normals,” was assumed in all scenarios. Although the estimates suggest a plausible range of future demands, they do not represent forecasts or predictions nor indicate upper and lower bounds of future water demand. Different assumptions or different future conditions could result in predicted or actual water demands that are outside of this range.Total water demand in the Kankakee subregion was an estimated 39 million gallons per day (Mgd) in 2010. The largest demand sector was public water supply. Public water demand was 18.0 Mgd in 2010, about 46 percent of the total regional demand. Most of that demand occurred in Kankakee County (14.3 Mgd). The next largest sector was self-supplied irrigation, livestock, and environmental (ILE). ILE demands were 13.2 Mgd in 2010, with most of that in Kankakee County (9.3 Mgd). Demands for self-supplied industrial -commercial and self-supplied domestic were 5.3 Mgd and 2.6 Mgd, respectively, in 2010. As with the other sectors, the majority of the demand was in Kankakee County. Because there are no thermoelectric power-generating facilities in the region, there is currently no demand for that sector. From 2010 to 2060, total demand in the region is estimated to increase by 1.6 Mgd under the LRI scenario, 14.6 Mgd under the CT scenario, and 36.0 Mgd under the MRI scenario. The largest increase for all three scenarios is expected in the ILE sector, primarily irrigated cropland. A smaller increase is expected in the industrial-commercial sectors for all three scenarios. Public supply demand is expected to increase under the CT and MRI scenarios, but decrease slightlyunder the LRI scenario. Self-supplied domestic demands decrease under all three scenarios. For the CT and LRI scenarios, there are no estimated demands for thermoelectric power generation. For the MRI scenario, it was assumed that a single plant would come online in 2020, with a constant annual demand of approximately 11 Mgd between 2020 and 2060. Three climate change scenarios, ranging from hot/dry to warm/wet, were analyzed to determine the impact that increasing temperature and changing precipitation patterns could have on water demands. Public water system demands were calculated to increase between 6.9 and 10.0 percent because of climate change, and increases in domestic demands were similar. Irrigation demands varied from a decrease of 2.5 percent in a wetter future environment to an increase of 10.7 percent in a drier environment. The impact of periodic droughts was also examined. For a severe drought, public water system demand was calculated to increase by 13.2 percent and cropland irrigation demand by 36.6 percent. Demands would return to normal once the drought ended.
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