ILLINOIS RESERVOIR REPORT

Last Updated: December 5, 2025

Illinois has several reservoirs and dams, primarily used for flood control, municipal water supply, and recreational activities. Major reservoirs in the state include Lake Shelbyville, Lake Springfield, Lake Decatur, and Rend Lake. These reservoirs receive water from various streams and rivers, including the Kaskaskia River, Sangamon River, and the Little Wabash River. Snowpack and mountains are not significant factors in Illinois hydrology, as the state has a relatively flat landscape. However, seasonal trends can affect water levels, with higher precipitation in the spring and lower levels in the summer. Drought conditions can also impact reservoir levels, with Lake Shelbyville experiencing record low levels in 2012 due to a severe drought. Overall, Illinois' reservoirs and dams play a critical role in managing water resources for the state's population and economy.

Illinois has several reservoirs and dams, primarily used for flood control, municipal water supply, and recreational activities. Major reservoirs in the state include Lake Shelbyville, Lake Springfield, Lake Decatur, and Rend Lake. These reservoirs receive water from various streams and rivers, including the Kaskaskia River, Sangamon River, and the Little Wabash River. Snowpack and mountains are not significant factors in Illinois hydrology, as the state has a relatively flat landscape. However, seasonal trends can affect water levels, with higher precipitation in the spring and lower levels in the summer. Drought conditions can also impact reservoir levels, with Lake Shelbyville experiencing record low levels in 2012 due to a severe drought. Overall, Illinois' reservoirs and dams play a critical role in managing water resources for the state's population and economy.