The state of Michigan has an advertising campaign, “Pure Michigan,” that highlights the state’s many natural attractions. The skiing! The parks! The beautiful Great Lakes!

The beautiful, non-potable Chicago River
The beautiful, non-potable Chicago River

I’m curious how they’ll rebrand the effort once those Great Lakes become home to raw sewage from Chicago. From ABC 7 Chicago (and via Stephen Lacey):

Water levels on Lake Michigan are the lowest in recorded history. If the level continues to drop, the Chicago River could reverse itself and send untreated sewage into Lake Michigan. …

“Our river is 70-percent sewage. I think we need to recognize that. This is an open sewer. It depends upon gravity to go away from us. If that gravity does not work with the lake going down, it goes the other way, and we have done nothing to deal with the contaminants that we need to actually invest in fixing,” Henry Henderson, Natural Resources Defense Council.

The Army Corps of Engineers said it is carefully monitoring the situation, and if lake levels continue to drop, they may have to modify how they operate the locks to limit the amount of water that goes into the lake, which would have an impact on recreational boats and barge traffic.

Why is the river full of sewage? Blame the Dave Matthews Band. Why might the river reverse? Blame the ongoing Midwest drought. Forty percent of the state of Illinois is still under drought conditions. And as reported by Reuters last November, Lake Michigan has been hit particularly hard by the drop in water levels.

The water level in Lake Michigan is within two inches of its December record low set 48 years ago. The lake is one of the five lakes that make up the Great Lakes, which cover 94,000 square miles and straddle the United States and Canadian border. …

Drew Gronewold, research hydrologist with the National Oceanic Atmospheric Administration’s (NOAA) Great Lakes environmental research laboratory said water levels have been dropping since the 1990s.

“Water levels naturally fluctuate and have been at low levels for 10 years. But this year of extreme high water temperatures increased evaporation rapidly and that helped draw down water levels,” Gronewold said.

Imagine a watering can with a long spout near its top. If the can is completely filled, water pushes up into the spout. As water evaporates, water drains back down from the spout into the can itself. Now imagine that the water in the spout is 70 percent untreated sewage.

Some good news: A lock at the end of the Chicago River may ensure that the river’s garbage water doesn’t contaminate the lake too badly. From Fox 32 Chicago:

In an operations center where Water Reclamation District engineers monitor and control flows between Lake Michigan and three local waterways, computer screens told an unusual story. The surface of the Chicago River was a tiny bit higher than the surface of Lake Michigan: 6/100ths of an inch, to be exact.

But, they said, very little water from the polluted river would end up in the lake, thanks largely to a network of recently modernized seawalls and gates.

Which is good news for the Michigan tourism bureau. “Mostly Pure Michigan” still has a ring to it. And it will be easy to spot parts of the lake to avoid. Right after St. Patrick’s Day, for example, you’ll be able to see a green plume where Chicago River seeps into the lake. The rest of the year, the plume will be brown.