asian carp epidemic forces chicago to reconsider design of water infrastructure – steven reiman


— The Chicago Sanitary and Ship Canal, built to protect Lake Michigan, now endangers the welfare of the Great Lakes

Originally intended to prevent waste from polluting the city’s drinking water, the Chicago Sanitary and Ship Canal reversed the flow of the Chicago River a century ago, diverting it from its natural course which empties into Lake Michigan, and sending it instead towards the Mississippi River.

Almost from the outset, the project was plagued by controversy. Downstream communities complained that they would be exposed to Chicago’s sewage; while members of the Great Lakes region worried that the reversal of flow, combined with Chicago’s enormous withdrawal of water for other municipal purposes, would slowly drain the Lakes. The Missouri Attorney General filed a suit during the canal’s construction asking the U.S. Supreme Court for a permanent injunction against its operation, however, the canal opened before any action could be taken, leading to a litigious battle that continues today.

While the amount of water withdrawn from Lake Michigan remains a major concern, today the canal is at the center of a new storm. When the course of the Chicago River was altered, it connected two watersheds, those of the Great Lakes and the Mississippi River, which had previously been isolated from one another. Now, aquatic species are able to travel freely between the two ecosystems.

 One such species is the Asian Carp, an extremely invasive fish originally found in China. Catfish farmers in the southern United States imported the Asian carp in the 1970’s in an effort to control algae growth in commercial ponds.  As a result of flooding throughout the last several decades, the carp has been washed out of those ponds and into other waterways such as the Mississippi and Illinois River.  Today, Asian carp are migrating north at a rate of 50 miles per year, threatening the fragile ecosystems of the Great Lakes.


 The carps’ voracious appetite, which made them prized cleaners in aquaculture ponds, makes them a great danger to the Great Lakes. Weighing up to 100 pounds, they are capable of consuming an amount nearly equal to their body weight each day. Combine this with their rapid growth and prolific reproduction, and the invasive carp are poised to out-compete native fish species, potentially depleting plankton and other small organisms, which form the base of the Great Lakes’ food web. At stake is not just the welfare of the ecosystem, but also the future of the Great Lakes’ $7 billion fishing industry.

 With the Chicago Sanitary and Ship Canal serving as the only link between the Mississippi watershed and the Great Lakes, it has become the focal point of efforts to prevent the spread of carp into the Lakes. While several control methods have been implemented, including the poisoning of large stretches of waterway and the introduction of electrical barriers which pulse a non-lethal current though the canal, deterring fish from passing, the DNA of two Asian carp species – the Bighead and Silver carp – have been found in Lake Michigan.  Now, the city of Chicago is debating whether it should restore the original flow of the Chicago River and close the Sanitary and Ship Canal all together, thus separating the two watersheds.

 The threat that the Asian carp pose to the Great Lakes is very real.  Their introduction could forever alter the ecology and economy of the world’s largest fresh water system.  This epidemic should be considered a wake up call, encouraging other states to reconsider aging infrastructure, which may pose new challenges in today’s changing environment.


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