Remembering the Great Chicago Flood 25 years later

CHICAGO (WLS) -- It may not rise to the level of the Great Chicago Fire, but 25 years ago another unforgettable disaster happened in Chicago's Loop: the Great Chicago Flood.

At the time, 124 million gallons of water rushed into the Loop's underground tunnel system. It left normally-packed streets deserted, grabbed national headlines and gave us a rarely seen look at the underbelly of this great city. The day Chicago sprang a leak was a doozy.

The Chicago River itself, at the Kinzie Bridge, drained like a giant bathtub.

John Russick of the Chicago History Museum recalled the disaster seen in the basement of buildings throughout the Loop, from Merchandise Mart to Marshall Field's - now Macy's.

"Here's one of the people calling in and reporting there's water, but also reporting there's fish in the water," Russick said.

The fish were the first clue this was no water main break. There is a labyrinth of old tunnels under downtown, used decades ago by a small train or trolley network to deliver freight and coal to Loop buildings. That tunnel network extends under the Chicago River. Twenty-five years ago, a section of that tunnel under the river collapsed. Enter: water.

"Imagine the river is level here, and the tunnel is here. Basically, the river is going to drain into these tunnels until they're full of water," Russick explained.

It shut down business in the Loop, closed the financial markets, even flooded the Kennedy Expressway at Hubbard's cave. And the vexing, critical question shortly followed: how do you plug the river?

"They were dumping all kinds of stuff in the river trying to plug the leak and nothing was working," recalled Richard Lanyon, former executive director of the Water Reclamation District.

Finally, engineers figured out how to seal off the tunnel on both sides of the river, stopping the faucet so to speak and leaving one big mess.

It's estimated the flood cost nearly $2 billion to fix, clean-up and in lost business. We learned later that a construction crew working on the river had earlier inadvertently damaged the tunnel beneath the riverbed. We also learned that the city was told of the fragile tunnel before it collapsed.

The remaining tunnels are still beneath our feet each day, holding power lines and communications wiring.