It is a component of the Chicago Area Waterway System, and is used to control water diversion from Lake Michigan into the river and for navigation.

The lock was built between 1936 and 1938 by the Sanitary District of Chicago primarily as a means of limiting diversion of water from Lake Michigan, but also as a component of the project to reverse the flow of the Chicago River to improve the water quality of the lake and for improved navigation.

[4] The lock requires 12–15 minutes to cycle through a typical water-level difference of two to five feet (0.61 to 1.52 m).

[2] Water level is controlled via gravity by partially opening and closing the lock gates.

The controlling works contains eight sluice gates along its piers, each measuring 10 feet (3.0 m) x 10 feet (3.0 m), allowing water from Lake Michigan into the river for navigational and sanitation purposes during normal weather operations, and for allowing water out of the swollen river into the lake during heavy rainfall periods as a measure of last resort for flood control purposes.