Water cribs in Chicago

The water cribs in Chicago are structures built to house and protect offshore water intakes used to supply the City of Chicago with drinking water from Lake Michigan. Water is collected and transported through tunnels located close to 200 feet beneath the lake, varying in shape from circular to oval, and ranging in diameter from 10 to 20 feet. The tunnels lead from the cribs to one of two water purification plants located onshore, the Jardine Water Purification Plant (the world's largest) and the South Water Purification Plant, where the water is then treated before being pumped to all parts of the city as well as 118 suburbs.

The city has had nine permanent cribs of which six are still standing and two are in active use.

The Two-Mile Crib was constructed as part of a scheme by Ellis S. Chesbrough in 1865, to help with the purification of the water because of damage caused by the city dumping sewage into the lake. Construction of the crib began in May 1864, miners and workers worked 24 hours a day and six days a week. The total completion of the project was in March 1867 and cost the city $380,784. Purified water was pumped to the Chicago Avenue Pumping Station which still stands to this day on North Michigan Avenue.

The Four-Mile Crib was put into service in 1891 to help with the problem of getting uncontaminated water to Chicago and various neighborhoods. To deal with this, a new crib was built even farther than the Two-Mile Crib. The brick alone cost $472,890.93, but the total project cost was $1,526,143.68. This crib was special, as there was a steam heating plant installed in 1898. This kept the crib at a temperature of 70 degrees and allowed plant workers to reside there during the winter, who helped to stop the formation of ice. In 1932, the Bureau of Lighthouses reported that a submarine cable had been laid and two rooms had been added on to the crib.

The 68th Street Crib was built in 1892 two miles offshore the eastern end of 68th Street. A cement hexagon-shaped crib with a brick structure atop, it originally supplied two tunnels, a 20-foot diameter tunnel to the Jardine Water Purification Plant and a 10-foot diameter tunnel to the South Water Purification Plant. The crib was equipped with a navigational warning light atop a steel-skeleton lighthouse and a fog bell that tolled every 12 seconds when needed.

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