Total streamflow across the Illinois River was last observed at 83,137 cfs, and is expected to yield approximately 164,901 acre-ft of water today; about 117% of normal. Average streamflow for this time of year is 70,854 cfs, with recent peaks last observed on 2015-12-28 when daily discharge volume was observed at 632,800 cfs.

Maximum discharge along the river is currently at the Illinois River At Valley City reporting a streamflow rate of 31,300 cfs. However, the streamgauge with the highest stage along the river is the Illinois River At Henry with a gauge stage of 16.25 ft. This river is monitored from 12 different streamgauging stations along the Illinois River, the highest being situated at an altitude of 1,202 ft, the Illinois River Near Kerby.

The Illinois River is a 273-mile-long tributary of the Mississippi River that flows through the state of Illinois. It was an important trade route for Native American tribes and European explorers, serving as a vital transportation artery for the region. The river's hydrology is heavily managed through a series of reservoirs and dams, including the Dresden, Marseilles, Peoria, and LaGrange Locks and Dams. These structures help to regulate water levels for navigation and flood control. The river is also used for recreational activities such as boating, fishing, and camping, and it supports a variety of agricultural uses in the surrounding areas. In recent years, efforts have been made to improve water quality and protect the ecosystem of the Illinois River.