The reversal of the Chicago River a century ago, to send the city's sewage to the Mississippi River instead of into Lake Michigan, was hailed as an engineering marvel. Now Michigan is suing Illinois to potentially re-reverse the river to prevent the movement of voracious, invasive Asian carp into the lake.
The suit, which is going to the Supreme Court, also challenges Chicago's controversial withdrawal of up to 2 billion gallons of water a day from Lake Michigan.
Environmental groups have long called for the ecological separation of the Great Lakes from the Mississippi River basin to curb the spread of invasive species and to retain Great Lakes water in the Great Lakes basin. It is estimated the Chicago diversion has lowered lakes Michigan and Huron by three inches.
The Chicago River was reversed by connecting it through a system of canals to rivers whose waters flow into the Mississippi. Varying degrees of ecological separation could be achieved by closing the canals: using sluice gates to allow lake water to flow but blocking fish or boats; or using measures such as bubble or sound "curtains," chemicals or electricity to limit the movement of fish and smaller organisms.
Electric barrier
Since 2002, the Army Corps of Engineers has run an electric barrier in the canal to block Asian carp. But tests by the University of Notre Dame and the Nature Conservancy in the fall found Asian carp DNA beyond the barrier near Lake Michigan, indicating that it might have failed to keep the voracious fish at bay.
If Asian carp make it into the Great Lakes, environmentalists and policymakers say, they could wipe out plankton that makes up the base of the food chain, severely impacting fishing and lake-based tourism.
"It's a matter of self-defense economically and ecologically for Michigan," said Michigan Attorney General Mike Cox.
Michigan's suit, filed Dec. 21, reopens a 1922 lawsuit filed by Great Lakes states challenging Chicago's right to divert water. That suit resulted in a consent decree limiting the amount of water Chicago sends to the Mississippi. Michigan's suit also calls for a preliminary injunction to force the temporary closure of locks, used for flood control and navigation.
"They've been saying they have this under control, but they really don't, and they're going back to the status quo," said John Sellek, a spokesman for the Michigan attorney general. "Their primary interest is keeping the waterway open, keeping that barge traffic on the canals. But Michigan's interest is far larger than that. The Great Lakes fishing industry is worth $7 billion all by itself, let alone the hundreds of thousands of jobs that are connected to the Great Lakes."
The Corps of Engineers and other federal, state and local authorities would probably be involved in closing the canals or other ecological separation measures, which could also be mandated through legislation.
If the canals were closed, barges could not travel from the Mississippi River into the Great Lakes. Freight would probably have to be transferred to trucks or rail cars and carried over land to Great Lakes ports. That would be a costly undertaking.
The national industry group for barge operators, which opposes closing the locks, says about a quarter-million truck trailers' worth of goods make the passage annually on barges. But national environmental groups say the potential economic impact of Asian carp and other invasive species in the Great Lakes make freight reconfiguration worth the cost.
A 2008 study by the Alliance for the Great Lakes found that ecological separation could be economically beneficial and improve efficiency of freight transport.
'Human-created problem'
The Natural Resource Defense Council has proposed that an environmentally sustainable intermodal freight facility be built to replace barge traffic into the lake, creating "green jobs" and curbing the invasive species risk.
"This way of moving goods may have made sense in the 19th century or 50 years ago, but are we still dependent on those same decisions?" asked Henry Henderson, NRDC Midwest program director. "We built a system without understanding the full implications. Now we have to design and build an engineered solution to a human-created problem."
An ecological separation would probably mean Chicago would have to revamp its wastewater infrastructure.
"The reason Chicago reversed the flow of the river was to protect Lake Michigan from sewage pollution, but that protection is no longer needed because Chicago and every city has the technology now to clean up sewage so it's safe to discharge it into the Great Lakes," said Andy Buchsbaum, National Wildlife Federation Great Lakes regional executive director, who noted that Milwaukee and other cities discharge treated sewage into the Great Lakes. "Instead of protecting Lake Michigan, the system is now the primary vector for the biggest pollution threat the Great Lakes have faced: invasive species."
Asian carp aren't the only invasive species transported through the canals. It seems likely that zebra mussels and round gobies were introduced to the Great Lakes in ballast from oceangoing ships and then made their way into the Mississippi River basin via the Chicago River and canals. Zebra mussels deplete plankton and clog water-intake structures. Round gobies compete destructively with native fish.
The electric barrier was originally proposed to block round gobies, but wasn't implemented fast enough. The barrier didn't operate at full strength until this year because of safety and other concerns. Now the Corps of Engineers plans to spend at least $6 million in stimulus funding on a stronger electric barrier.
"I was skeptical of that barrier from the get-go," Henderson said. "This has all been ad hoc herky-jerky responses to discreet problems, when the underlying problem is staring us in the face."
Buchsbaum called the Michigan lawsuit "seismic for the Great Lakes" because it addresses the invasive species threat but also reopens the nearly century-old legal battle over Chicago's diversion of Great Lakes water.
The Great Lakes-St. Lawrence River Basin Water Resources Compact — signed by President George W. Bush last year after a decade-long legislative process — bans almost all diversions of Great Lakes water out of the basin, with Chicago given the only significant exemption.
About 1 percent of the Great Lakes' water is replenished each year, and advocates worry that unchecked diversions could slowly drain the lakes.