Chicago River Flowing Backwards Would Be Least of Region's Concerns
http://www.bloomberg.com/news/2013-01-31/chicago-river-flowing-backwards-would-be-least-of-region-s-concerns.html
Trump Tower and the Wrigley Building along on the Chicago River. The worst U.S. drought since the 1930s is lowering the level of Lake Michigan, which in theory could reverse the flow of the Chicago River. Photographer: George Rose/Getty Images
The headlines were alarming: "Drought Could Reverse Flow of Chicago River," hailed the website of WLS-TV, the local ABC News affiliate. "Ongoing Drought Could Send the Chicago River Flowing in Reverse," read Smithsonian magazine's normally sedate web pages.
It turns out, a backwards flow may be the least of the rivers concerns.
Heres the scenario: the worst U.S. drought since the 1930s is lowering the level of Lake Michigan, and if it drops another 6 inches or so this winter, it could fall below the level of the Chicago River. That means the dirty waters of the Chicago River, which were diverted 100 years ago to preserving the relatively pristine lake, would be sucked backwards.
In practice, three sets of locks that divide the river from the lake would only allow a relatively small amount of river water to leak back into the lake when the locks are opened to ships, says Margaret Frisbie, executive director of Friends of the Chicago River. Its roughly the equivalent of putting a thimbleful of dirty water into a bathtub.