Kankakee Watershed Region
The Water Survey's 2019 report on the Kankakee water supply sub-region, which includes Kankakee, Iroquois, and Ford counties, shows that there are significant water resources available to meet demands in the region, 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 most sensitive area is southeastern Kankakee and northeastern Iroquois counties, where irrigation pumping can cause dewatering of the dolomite.
Although the Kankakee River has reliable water for meeting current power generation and public water supply needs, cooling water withdrawals from the river could be limited on account of protected minimum flows and water temperature criteria. The recent identification of state endangered species in the Kankakee River may change the biologic integrity rating of the river, potentially requiring increased protected minimum flows. If this happens, new Kankakee River water users would need a backup water supply for a longer period. Some communities in Will and Grundy Counties have explored using the Kankakee River as a primary water source due to unsustainable withdrawals from the sandstone aquifer, and while the largest, Joliet, has made a decision to switch to a Lake Michigan water supply, other communities are still considering their options.
Updates for the demand and supply analyses can be found in this StoryMap: Kankakee Watershed Region Water Supply Planning
