Total streamflow across the Mackinaw River was last observed at 327 cfs, and is expected to yield approximately 649 acre-ft of water today; about 17% of normal. River levels are low and may signify a drought. Average streamflow for this time of year is 1,893 cfs, with recent peaks last observed on 2019-05-04 when daily discharge volume was observed at 26,190 cfs.

Maximum discharge along the river is currently at the Mackinaw River Near Green Valley reporting a streamflow rate of 169 cfs. This is also the highest stage along the Mackinaw River, with a gauge stage of 13.49 ft at this location. This river is monitored from 2 different streamgauging stations along the Mackinaw River, the highest being situated at an altitude of 611 ft, the Mackinaw River Near Congerville.

The Mackinaw River flows through central Illinois, spanning 130 miles from its headwaters in McLean County to its confluence with the Illinois River in Tazewell County. The river's name comes from the Native American word "Makinauk," meaning turtle. The Mackinaw River has a drainage area of 1,800 square miles and is fed by several tributaries. The river has two major reservoirs, including the Evergreen Lake and Lake Bloomington, which serve as sources of drinking water for nearby communities. The river is also used for recreational activities such as fishing, canoeing, and camping. It is a popular spot for fly fishing and is home to several species of fish, including smallmouth bass and channel catfish. The river also supports agricultural activities, including crop irrigation and livestock watering.