Leading Great Lakes advocates are calling for federal leadership and funding for "ecological separation" of the Great Lakes from the Mississippi River basin to protect both great watersheds from the perils of invasive species.

The November 12 announcement comes with the release of a new Alliance for the Great Lakes report that outlines six options for separating the watersheds and halting the transfer of species between them.

They are linked by the Chicago Waterway System, a complex system engineered in 1900 to reverse the flow of the Chicago River, which carries Chicago's wastewater away from Lake Michigan.

"The Great Lakes and the Mississippi River are at risk because of a connection that's nothing natural," said Alliance Vice President for Policy Joel Brammeier, lead author of the report. "Fifteen miles of water and an experimental electric barrier are all that's standing between the Great Lakes and Asian carp. We've got to get serious about a real solution."

Chicago Mayor Richard M. Daley noted that Asian carp in the Mississippi River were a known threat to the Great Lakes in 2003, when the city hosted a pre-emptive strike: the Chicago Aquatic Invasive Species Summit.

"We have been asking for years to complete these electrical barriers," Mr. Daley said. "It's time for our federal, state, and local partners to follow through on keeping these two great natural resources safe."

A 2003 analysis suggested that separation of the systems could reasonably be achieved within 10 years. Five years have now passed and many millions of dollars have been spent, the Alliance reports, while making progress on even interim steps such as a permanent electrical barrier has been difficult.

Although Asian carp, known to eat up to 20% of their body weight in plankton daily, are the most pressing threat to the Great Lakes, the connection poses threats to both watersheds. The round goby and zebra mussel have both invaded the Mississippi River basin in the past decade through the Chicago Waterway System.

This complex waterway system supports thousands of recreational boaters and the flow of approximately 25 million tons of bulk commodities annually. The study advises that investment in new infrastructure can benefit users while eliminating the risk of invasion.

"Invaders like Asian carp are unpredictable, but their effects are catastrophic and irreversible," said Mr. Brammeier. "Every day we allow them closer to the Great Lakes, the threat grows larger and the solutions more expensive."

The report identifies several sites upstream from the electrical barrier as likely candidates for ecological separation. Although some changes to navigation would be unavoidable, the Alliance acknowledges, these locations would allow continued use of the system for wastewater disposal and minimize the impacts on the flow of goods and recreational boaters. The study suggests these traffic flows could even be enhanced if ecological separation was addressed as part of a revitalization of the Chicago-area navigational infrastructure.

The Great Lakes Fishery Commission and Great Lakes Fishery Trust contributed to funding the study.

The full report, "Preliminary Feasibility of Ecological Separation of the Mississippi River and the Great Lakes," can be read online at www.greatlakes.org.