The Nature Conservancy Supports Ecological Separation in the Chicago Area Waterways

Three Options in New Report Provide Sound Basis for Decision-Making, Action

Chicago, Illinois | January 31, 2012

The Nature Conservancy recommends action on a new report that lays out three possible solutions to prevent invasive species from crossing into or out of the Great Lakes through the Chicago canal system.

Currently, two species of Asian carp threaten the Great Lakes ecosystem and a variety of industries relying on the lakes. Each solution is designed to prevent carp and other harmful non-native species from reaching Lake Michigan while allowing commercial shipping, tourism, recreational boating and other uses to proceed, and addressing wastewater discharge and storm-water issues.

“The three options are an excellent basis for discussion toward identifying and implementing a permanent solution, and the need is urgent,” says Leslee Spraggins, Illinois state director of The Nature Conservancy. The report, “Restoring the Natural Divide,” was released by the Great Lakes Commission and the Great Lakes and St. Lawrence Cities Initiative.

Spraggins emphasized that a large population of Asian carp – big head and silver species – are not far downstream of the Chicago Ship and Sanitary Canal’s electrical barrier that stuns and deters the carp from swimming toward Lake Michigan.

In October of 2010, The Nature Conservancy and Notre Dame scientists discovered DNA evidence that Asian carp are on the lake side of the barrier, and if they establish themselves in the lakes, they threaten ecological disruption by outcompeting native species for food. The carp could also cause an explosive growth of algae.

The Nature Conservancy supports ecological separation: meaning permanent measures that prevent transfer of live organisms between the Great Lakes and Mississippi River basins. The report provides three options to secure ecological separation through Chicago-area waterways. Neither the report’s authors nor the Nature Conservancy favor one option over another – leaving that decision to the stakeholders. But the Conservancy offers its scientific expertise to assist in and facilitate the decision-making.

The Asian carp’s environmental threat to the Great Lakes is real. The U.S. Geological Survey recently confirmed that there is suitable habitat in the Great Lakes basin to support a self-sustaining population of Asian carp. Invasive species are currently costing the Great Lakes states’ economies by some estimates hundreds of millions of dollars each year. The region cannot afford additional costs at a time when reduced tax revenue and budget cuts strain local resources.

The Chicago waterways are “a two-way street,” Spraggins says, adding there are 29 aquatic invasive species in the Great Lakes that could threaten the Mississippi River basin. “What’s not often understood is that an invasive fish swimming from Lake Michigan will not be stopped by the electrical barrier. The barrier would stun the fish, but the water flow will let the fish simply float downstream toward the Mississippi,” she says. “Only ecological separation will protect both the Great Lakes and Mississippi River Basins.”

The Nature Conservancy (TNC) has been a leader in fighting aquatic invasive species. Here are four of many examples:

  • TNC and University of Notre Dame developed and deployed a new genetic monitoring system that tested for the presence of Asian carp DNA in area waterways that indicated the likely presence of fish in the canal system.
  • TNC works in the Toledo, Ohio area to get rid of invasives such as phragmites that outcompete native species and damage coastal wetlands.
  • TNC, University of Notre Dame, State Department of Natural Resources, U.S. Forest Service and others have undertaken widespread surveillance for problematic water weeds in Indiana, Michigan, Illinois, and Ohio, to inform agency eradication and containment efforts.
  • TNC scientists are working on aquatic invasive issues at our largest preserve – Emiquon – along the Illinois River near Havana.


The Nature Conservancy is a leading conservation organization working around the world to conserve the lands and waters on which all life depends. Visit The Nature Conservancy on the web at To learn about the Conservancy’s global initiatives, visit To keep up with current Conservancy news, follow @nature_press on Twitter.


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