"You can't force a boat through it."
Chicago tour guides often marvel at the epic engineering feat of the late 19th Century that reversed the course of the Chicago River, diverting its noxious flow away from Lake Michigan (the city's source of drinking water). But what those guides never tell you is where all of that sewage went. In short, it was flushed down the I&M Canal and the Des Plaines River, to Joliet.
The water is nastier here than it is in Chicago. They have as much sewage there, but the putrefaction is well under way when it gets down here. Down on Lake Joliet it is thick; you can’t force a boat through it.
Thank goodness for modern sewage treatment technology.