The Lake Was Also the Tap
In its natural course the Chicago River carried the city’s sewage out into Lake Michigan, and Lake Michigan was where Chicago drank from. Whatever the streets washed into the current was heading for the same supply that came out of the taps.
That supply still comes from offshore. It enters through intake cribs standing far out from the beaches, travels through tunnels beneath the lake bed and reaches purification plants on land. Seen from a boat, the cribs look like small forts painted red and white, keeping watch over the city’s tap.
The fix Chicago settled on was not to stop the flow but to give it somewhere else to go.
A District Made for the Job
Illinois lawmakers created the Sanitary District of Chicago to do it, and local voters approved the new body by a wide margin. It still exists under a longer name, the Metropolitan Water Reclamation District of Greater Chicago, and it still looks after everything the city has finished with and sent down the drain.
The plan needed friends downstate, because that was where the outflow would end up. So the new canal was made wide enough for steamboats, which turned a drainage scheme into a shipping route between the Great Lakes and the Gulf of Mexico. Towns along the way were being offered boats as well as Chicago’s drainage. It was a sensible bargain, and it won the support the district needed.
The chief engineer, Isham Randolph, later took that experience to the Panama Canal, and other engineers from the project followed. A city trying to keep its taps clean ended up training people for a canal between oceans.
The Canal That Turned the River Round
The Chicago Sanitary and Ship Canal opened in 1900, and with it the Main Branch and the South Branch gained a new exit. Their flow now headed away from the shore, along the canal to the Des Plaines River, then into the Illinois River and on towards the Mississippi. What had drained east now drained south-west, and the city’s waste went with it, away from the intakes.
The work went on beyond the downtown channel. The North Shore Channel followed, and the Cal-Sag Channel later did the same job for the Calumet rivers further south. The American Society of Civil Engineers eventually named the system among the wonders of American engineering, which is a generous description of a set of drains, and an accurate one.
The Lock That Keeps the Lake Higher
A reversal does not hold by itself. The current runs inland while the river sits below Lake Michigan, and the federal rules for the waterway say so plainly: keep it lower than the lake, except after very heavy storms. At the mouth, the Chicago Harbor Lock keeps them apart. The Sanitary District built it later, as part of the same project, and its gates stay closed except when boats need to pass.
Filling and emptying the chamber is left to gravity. The gates are opened a little and the difference in level does the rest, which is the whole arrangement in miniature: a high side, a low side and gravity working for the city.
This is the part of the story a visitor can ride. Sightseeing boats heading out into open water pass through the chamber, and from the deck you can watch the gates swing and the surface settle to a new level. The lock works through the boating season and closes for maintenance in winter, from mid-November until mid-April, so a trip through it belongs to the warmer months.
Lockport, Where the Flow Is Let Go
The other end of the arrangement lies downstream at Lockport, where the Lockport Controlling Works and Powerhouse regulate how much leaves the canal. The powerhouse is a classically designed building under a red roof, listed on the National Register of Historic Places, and it still turns the passing current into hydroelectric power.
There is a pleasing thrift to that. What Chicago sends away does a last job on its way out.
Watching the River Go the Other Way
Back downtown, cleaner water has changed how Chicago treats its banks. Daniel Burnham’s Plan of Chicago imagined riverside promenades, but pollution made that look like wishful thinking for a long time. The Riverwalk now runs along the south bank of the Main Branch from Lake Street to the lakefront. It was built in stages, and each block between the bridges has a character of its own.
The Cove sits low enough for kayaks to put in. The Jetty has floating wetland gardens and room to cast a line, and game fish have returned. Along the walk, the McCormick Bridgehouse & Chicago River Museum celebrates the waterway and its movable bridges. If you would rather start with the rest of Chicago, our friendly guide to the Windy City covers the sights away from the water.
Once a year the river puts on a costume. On the Saturday before St Patrick’s Day, the plumbers’ union scatters an orange powder into the Main Branch from a pair of motorboats, and the water downtown turns a startling green. The idea fits the rest of this story rather neatly: it grew out of the dye city workers once used to trace illegal drains into the river. Even in costume the river keeps its orders, carrying the colour away from the lake.
My own favourite spot is the lawn at The Confluence, at the western end of the walk, laid out for sitting and watching the river flow by. Stay there a while and the detail that is easy to miss becomes obvious: what passes in front of you is leaving the lake, not arriving at it. Plenty of cities have a river running through them. Chicago has one that still does as it was told.
