The lock and dam are 326 river miles (525 km) from the Mississippi-Illinois confluence. The lock chamber measures 1,000 by 110 feet (305 m × 34 m) with a maximum lift capability of 5 feet (1.5 m).[1][2] The lock contains a pair of sector gates at either end, which were chosen as they both reduce the cost of engineering and are more conducive to operations in a waterway which can reverse direction.[1][3] The dam measures 293 feet (89 m) and includes 4 vertical sluice gates.[4]
The lock and dam are used to maintain a 9-foot navigation channel, and for flood control purposes, primarily to limit diversion from the lake during normal periods, and mitigation of backflows into Lake Michigan during large storm events which reverse the direction of the river.[1]
History
Predating the lock and dam was the Blue Island Lock, constructed at the eastern end of the Cal-Sag Channel in 1922. Nearly as soon as its completion, there was already lobbying by various industries along the waterway to expand the size of the lock, which measured 360 by 50 feet (110 m × 15 m). A report by the United States Army Corps of Engineers (USACE) in 1933 proposed, among other things, expanding the size of the lock to 600 by 110 feet (183 m × 34 m) to improve navigation.[1] It would not be until 1946 when Congress would authorize funding for the improvements to the Cal-Sag Channel.[1] The location of the new lock and dam 7 miles (11 km) upstream from the old controlling works at Blue Island was chosen to improve the ability to control backflow events into the lake during heavy storms from the polluting industries along the Grand Calumet River and Little Calumet River and the outfall of the Calumet Water Reclamation Plant.[5] Construction began in 1957, and was completed in 1960. However, the lock portion was not put into operation until July 1, 1965, when the Blue Island Lock was finally decommissioned.[1][5]
