Water Demand in the Rock River Water Supply Planning Region, 2010-2060

Estimates of water demand in the Rock River Water Supply Planning Region (WSPR) 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 42 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 Rock River WSPR was an estimated 1332 million gallons per day (Mgd) in 2010. Demand for self-supplied water for thermoelectric power generation dominates water demand in the region, making up 87 percent of the total water use, or about 1160 Mgd. Water for thermoelectric power generation is used almost entirely for cooling and generally returned to the source water body from which it was withdrawn, and thus is considered to be mainly non-consumptive. The consumptive loss, mainly in the form of evaporation, was estimated to be about 67 Mgd in 2010, or about 3.7 percent of the total. The CT and LRI scenarios assumed that regional gross thermoelectric power generation remains constant from 2010 to 2060, with no change in water demand. The MRI scenario assumed that one new thermoelectric plant having a gross capacity of 1200 MW with a closed-loop cooling system supplied with surface water would begin operations in Lee County in 2030. This would increase regional water demand for the thermoelectric power generation sector by 11 Mgd to 1171 Mgd.The second most important demand sector in the Rock River WSPR was public water systems, at 79 Mgd in 2010. Two counties accounted for more than 60 percent of the public water system demand, Winnebago County accounting for about 39 percent and Rock Island County about 23 percent. The irrigation, livestock, and environmental (ILE) sector was the next most important sector, with a demand of 52 Mgd in 2010, and most of this demand was for irrigation of cropland. Two counties, Whiteside and Lee, accounted for about 61 percent of the 2 irrigation demand in the region. The self-supplied industrial-commercial sector had a demand of 28 Mgd in 2010, with Rock Island County accounting for about half of this demand. The self-supplied domestic sector had the smallest demands, with 11 Mgd in 2010. Domestic demand was spread fairly evenly across the region, ranging from 0.4 Mgd (Lee County) to 1.6 Mgd (Ogle County). From 2010 to 2060, total demand in the region, not considering thermoelectric power generation, is estimated to decrease by 9 Mgd under the LRI scenario and increase 51 Mgd under the CT scenario and 141 Mgd under the MRI scenario. Most of the increase in total demand is accounted for by increases in self-supplied ILE demand, primarily for irrigated cropland. ILE demand is predicted to increase from between 7 Mgd (LRI) and 92 Mgd (MRI). The decrease in demand predicted by the LRI scenario is primarily due to decreasing demand (-16 Mgd) in the public supply sector. The sector totals for the thermoelectric power generation and industrial-commercial sectors are subject to revision, specifically, the simulation of new power plants and water-intensive industrial facilities as well as the retirement of existing facilities.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 6.0 and 8.7 percent because of climate change, and increases in domestic demands were similar. Irrigation demands varied from a decrease of 3.2 percent in a wetter future environment to an increase of 10.1 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 8.7 percent and cropland irrigation demand by 34.0 percent. Demands would return to normal once the drought ended.Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewedOpe

Water Demand in the Kankakee Water Supply Planning Subregion, 2010-2060

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.Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewedOpe

Water Demand in the Middle Illinois Water Supply Planning Region, 2010-2060

Estimates of water demand in the Middle Illinois Water Supply Planning Region (WSPR) 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 24 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 Middle Illinois WSPR was an estimated 866 million gallons per day (Mgd) in 2010. Demand for self-supplied water for thermoelectric power generation dominates water demand in the region, making up 76 percent of the total water usage, or about 655 Mgd. Water for thermoelectric power generation is used almost entirely for cooling and generally returned to the source water body from which it was withdrawn, and thus is considered to be mainly non-consumptive. The consumptive loss, mainly in the form of evaporation, was an estimated 77 Mgd in 2010, or about 12 percent of the total. The CT and MRI scenarios assumedthat regional gross thermoelectric power generation remains constant from 2010 to 2060, with no change in water demand. The LRI scenario assumed that a single 136-megawatt (MW) generator at the E.D. Edwards power plant was retired in 2015, reducing the regional water demand to 588 Mgd.Self-supplied industrial-commercial was the next most important water demand sector in the Middle Illinois WSPR, with a demand of 150 Mgd in 2010, with Peoria County accounting for about 85 percent of this demand. The next most important demand sector was public water systems, at 46 Mgd in 2010, with Peoria County accounting for about 52 percent. The two remaining sectors, domestic and irrigation, livestock, and environmental combined accounted for 14 Mgd in 2010, or less than 2 percent of the total demand in the region.From 2010 to 2060, total demand in the region, not considering thermoelectric power generation, is estimated to increase by 241 Mgd under the LRI scenario, 320 Mgd under the CT scenario, and 425 Mgd under the MRI scenario. Most of the increase in total demand under all scenarios, particularly the CT and MRI scenarios, is accounted for by increases in self-supplied industrial-commercial demand. Sector totals for the thermoelectric power generation and industrial commercial sectors are subject to revision, specifically, the simulation of new power plants and water-intensive industrial facilities as well as the retirement of existing facilities.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 6.1 and 9.1 percent because of climate change, and increases in domestic demands were similar. Irrigation demands varied from a decrease of 11.5 percent in a wetter future environment to an increase of 1.3 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 12.4 percent and cropland irrigation demand by 36.6 percent. Demands would return to normal once the drought ended.Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewedOpe

Water Supply Planning: Middle Illinois Progress Report

This report presents a summary of 1) the technical information assembled to describe existing water availability and sources of supply within the 7-county (LaSalle, Livingston, Marshall, Peoria, Putnam, Stark, and Woodford Counties) Middle Illinois River Region in central Illinois (Figures 1 and 2) and 2) the development of preliminary computer models that will be used in future studies to estimate impacts to water availability resulting from future water development in the region. Through funding by the Illinois Department of Natural Resources (IDNR), the Illinois State Water Survey (ISWS) and Illinois State Geological Survey (ISGS) prepared this document for the Middle Illinois Regional Water Supply Planning Committee (MIRWSPC) to aid in the development of a plan for meeting the future growth of water supply demands within the basin to the year 2060. It contains background information to provide an overview of management criteria and an understanding of the constraints and policies used in conducting analyses and making decisions concerning water usage. Models will be applied to a broad range of conditions, including a set of selected future water use scenarios to more fully characterize water availability within the Middle Illinois River Region to the year 2060. In addition, as the MIRWSPC deliberates and prepares its water supply planning document, the information presented in this report will be reviewed and, in some cases, additional analysis may be performed and results revised. A more complete reporting of the model development, the results of the scenario simulations, and subsequent work concerning water availability will be published at the end of that forthcoming study. The existing technical information compiled as the first task of this study includes a review of previous analyses and publications dealing with the Middle Illinois River Region’s water resources; collection of hydrogeological and hydrologic data, primarily as needed for modeling; and, in certain cases, additional analyses of that data, such as data mining of well records and yield analyses of surface water supply sources. This compiled information focuses on the three primary sources of water supply within the Middle Illinois River watershed: 1) direct withdrawals from the Illinois River; 2) public supply systems using the Vermilion River and off-channel reservoirs at Pontiac and Streator; and 3) groundwater from within the Middle Illinois River basin. A companion report has been published (Meyer et al., In preparation) evaluating water demand scenarios out to 2060 for the Middle Illinois River, Northwest Illinois, and Kankakee River Regions.published or submitted for publicationis peer reviewedOpe

Water Supply Planning: Middle Illinois Assessment of Water Resources for Water Supply-Final Report

Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewedOpe

Water supply planning: Kankakee watershed assessment of water resources for water supply

This report examines the impacts of current and future demands on water supplies for the Kankakee Watershed Water Supply Planning Subregion (WSPR) in northeastern Illinois, an area comprising most of Kankakee and Iroquois Counties and portions of Ford, Will, Vermilion, and Grundy Counties that intersects the Kankakee River watershed boundary. Initial water demand scenarios were developed for a three-county region (Ford, Iroquois, and Kankakee) out to 2060 for five major water sectors, including thermoelectric power generation, public supply, self-supplied domestic, self-supplied industrial and commercial (IC), and self-supplied irrigation, livestock, and environmental (ILE), and are described in a companion report (Meyer et al., 2019). Total water usage in 2010 was estimated to be 39 million gallons per day (mgd), with two sectors, public supply and ILE, accounting for more than 80 percent of the demand in the region. Most of the ILE demand was for crop irrigation. Self-supplied IC accounted for 13 percent and the domestic sector 6 percent of the usage. Significant water resources are available to meet demands in the Kankakee WSPR, including both groundwater and surface water. Two major aquifer systems occur in the region: (1) productive sand and gravel aquifers, primarily in the south where the Mahomet Aquifer is encountered; and (2) weathered Silurian-Devonian dolomite, which is the most productive aquifer system in the region. Both the dolomite and Mahomet Aquifers are overlain by clay over most of the watershed, limiting leakage from shallower sources. The deeper Cambrian-Ordovician sandstones are generally too saline in this area to use as a water supply, although they are heavily used just outside of the watershed boundary in Will, Kendall, and Grundy Counties. Although the aquifers are generally thought to be adequate to meet most expected future demands, there are some sensitive areas that should be monitored closely. The most important area appears to be southeastern Kankakee and northeastern Iroquois Counties, where demands for irrigation water are highest on account of sandy soils. These demands are met from the dolomite aquifers and have been shown to result in dewatering of the dolomite during the irrigation season.Water quality in the Silurian-Devonian dolomite aquifer system is generally good. At a few locations, nitrate and chloride concentrations are elevated, but at concentrations below their respective drinking water standards. Water moves relatively rapidly from land surface into the Silurian-Devonian dolomite aquifer where it is near land surface, especially in the northern half of the region; aquifer protection activities should be a priority in these areas. The primary surface water sources in the Kankakee WSPR are the Kankakee and Iroquois Rivers. Currently there are four entities withdrawing water from the Kankakee River in the planning region: Aqua Illinois-Kankakee Division, which supplies the city of Kankakee, the city of Wilmington, Exelon Dresden Station, and Exelon Braidwood Generation Station.Although the Kankakee River has reliable water for meeting current power generation and public water supply needs, the cooling water withdrawals from the river could be limited on account of protected minimum flows and water temperature criteria. Therefore, both Dresden and Braidwood plants have a considerable storage capacity in their cooling ponds to buffer the impact of the minimum flow restriction. With increasing water demand and potential climate change, the frequency and duration of the minimum flow restriction may be increased in the 2 future. Both power plants using the Kankakee River for cooling water may rely on storage water more frequently.Water demand from within the watershed is not expected to increase dramatically in the future. However, large portions of Will County are at risk to dewatering of the Cambrian-Ordovician sandstone aquifers. As a result, communities within these at-risk areas are seeking alternate water supplies in anticipation of these impacts. One possible option is the Kankakee River. As part of the process of exploring alternative supplies, both Joliet and Godley have requested withdrawing a large amount of water from the lower reach of the Kankakee River. The communities served by this water lie primarily outside of the watershed, so both withdrawal and consumptive use of Kankakee River water could increase substantially. Unlike within the watershed, water demand for these communities outside of the watershed is expected to increase. Another unknown is how water demand will be met in the future by industries along the Des Plaines River. Many of these industries also rely on the at-risk sandstone aquifers, so the long-term viability of their sandstone wells is contingent on decisions by communities.The major concern with increasing water demand on the Kankakee River is the minimum flow restriction and how to supplement the river water when it is not available during drought conditions, especially when the water is diverted out of the watershed, as the wastewater may not be returned to the river. Other backup supplies are of limited availability in areas of sandstone risk, as currently the sandstone aquifers are likely to be the only viable backup option; however, there are questions about its viability under increasing demand. Off-channel storages and/or abandoned storage pits could also be explored to provide additional backup supply.As a result, conjunctive water management that accounts for impacts on both river and groundwater supplies will be essential moving forward. Water users within the Kankakee River watershed should be cognizant of this potential future demand on the river. Available flow on the Kankakee River during low-flow periods may be contingent on whether the communities in Will County also tap into it as a water supply, so water planners currently using or anticipating growth in use of the Kankakee River water should stay informed on planning decisions outside of the region. Sandstone users considering using the Kankakee River as a backup supply are also currently working with the ISWS to evaluate the viability of the Kankakee River as a backup supply under low-flow scenarios on the Kankakee River. This is critically important because of the rapid response of the sandstone aquifer when demands change.Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewedOpe