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The Dead Zone, Chicago Sewage, and Asian Carp

Chicago Portage or Mud Lake, the Continental Divide between Drainage to the Gulf of Mexico and Drainage to Lake Michigan

Over a year ago I wrote that Chicago is the largest contributor of nutrients to the Dead Zone in the Gulf of Mexico. In 1848 construction workers on the Illinois and Michigan Canal broke through the low continental divide, located several miles outside of Chicago, that separates drainage to the Gulf of Mexico from drainage to Lake Michigan and the Atlantic Ocean. The canal served as a navigation link between Lake Michigan and the Illinois and Mississippi Rivers.

In 1900 the City of Chicago decided to stop depositing its sewage in the Lake Michigan, from which it also drew its drinking water, and replaced the Illinois and Michigan Canal with the Chicago Sanitary Canal, which connected to the Des Plaines River and drainage to the Gulf of Mexico. Okay, this is old news. You can read the full history in my earlier post.

The canal that is handy for sending Chicago’s sewage south turned into a major navigation route between the Gulf of Mexico and Lake Michigan.

String of Carp caught at Lock and Dam #26, Upper Mississippi River, Alton, Illinois

It also may turn into a major conduit for silver carp from the Mississippi and Illinois rivers into Lake Michigan. The Great Lakes fishing industry is in an uproar and want the Chicago Sanitary Canal closed to keep the carp out of the Great Lakes. Of course the navigation industry is also up in arms about the thought of losing an important navigation channel to the fish. In short folks are lining up on both sides of the issue, keeping the connection between the Mississippi-Illinois Waterway and Lake Michigan or severing it.

The carp have a taste for algae. Fish farmers introduced the carp to their ponds to clean up the algae. However, they excrete phosphorous and nitrogen, which produce more algae, which grow, die, and decay, creating low-oxygen conditions. The fish got loose into the Mississippi during the Flood of 1993 and have been racing north even since. They also feed on zooplankton, which feed on algae, creating more algae and more low-oxygen conditions. And, it breeds like rabbits,  grows to thirty pounds fast, and hates loud noises. Run a noisy, high-speed motor boat across the river, or even a small trolling motor, and the fish leaps out of the water and into your boat. People have been hurt.

The concern is that the carp will take over the food supply in the Great Lakes and destroy the existing fisheries.

The good news maybe that there are not enough algae in Lake Michigan to keep the carp fat and happy, because the zebra mussel got there first on the hulls of those ships, which navigate the Chicago Sanitary Canal from the Gulf of Mexico with the critters attached.

Governor Pat Quinn of Illinois has decided, “If you can’t beat ’em, eat ’em.” In July he made a deal with the Beiging Zhuocheng Aminal Husbandry Company to ship Asian carp, processed in Illinois, to China, where the Chinese have a taste for the fish.

After Katrina, Gov. Quinn, then Lt. Gov. Quinn offered to send sediment dredged from the Illinois River to Louisiana to rebuild the marshes. The man is not without an imagination.

The summer 2010 issue of Our Mississippi, the publication of the Rock Island District of the Corps of Engineers, has three recipes for carp: fried carp, carp with fresh berries, and carp cakes.  You will find the recipes on page 7.

Back to the Dead Zone. The other major contributor of nutrients to the Gulf of Mexico are wheat, corn, and soybean fields of the Mississippi Drainage Basin, which stretches from the Appalachians to the Rockies and from the divides that hold the Great Lakes south. NASA has a video that explains the Dead Zone.

Farmfields from levee set a mile east of the Mississippi at Columbia, Illinois

The Mississippi has been high since early spring. The field at the Illinois end of the Jefferson Barracks bridge between south St. Louis County, Missouri and Monroe County, Illinois has been flooded for the whole summer and for the better part of three years. Because the river has been high, the Dead Zone, which usually appears in June, arrived in August.

Drainage Basin of the Mississippi River, from NASA

Bob Marshall has an article in today’s New Orleans Times-Picayune, which explains the Dead Zone as well as anybody. Folks from the National Wildlife Federation flew over the Breton Sound and the Chandeleur Islands last week, looking for oil, and found the milky-red Dead Zone instead.

NASA Image of the Dead Zone


One Response

  1. […] have all learned about the Chicago Sanitary Canal, designed to deliver Chicago’s sewage to the Mississippi. I have been writing about it for a […]

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