The record rainfall last week in Chicago overwhelmed the  deep tunnel and surface reservoirs, resulting in 99 billion gallons of stormwater and sewage being dumped into Lake Michigan. Here's a newspaper account...

The deep tunnel—a major engineering marvel, shown in the photo—will be toured by GLCC members attending the annual meeting in October.

To put it in perspective, this sewage dump would be the equivalant of 247,500,000 boats dumping their 40 gallon holding tanks into Lake Michigan