“Physically separating the Great Lakes and Mississippi River watersheds is the best long-term solution for preventing the movement of Asian carp and other aquatic invasive species, and our report demonstrates that it can be done,” said Tim Eder, executive director of the Great Lakes Commission.

The threat of Asian carp looms large for communities in the Great Lakes region. The lakes provide over 35 million residents with drinking water, contain 20 percent of the Earth’s fresh surface water, and support a thriving tourism industry and world-class fishery, which generates an estimated $7 billion in economic activity annually.

Voracious feeders that can grow up to 90 pounds, Asian carp have overrun other ecosystems and could cause irreversible damage to the Great Lakes if allowed entry. Once established, invasive species are nearly impossible to eliminate.

“This is a unique opportunity for both protection of the Great Lakes and Mississippi River and for a Chicago waterway system for the 21st century and beyond,” said David Ullrich, executive director of the Great Lakes and St. Lawrence Cities Initiative. “No single use of the CAWS, including transportation, flood control and wastewater treatment, can be considered individually. The system requires an integrated approach and that is what we have taken.”

The three separation alternatives include a down-river single barrier between the confluence of the Chicago Sanitary and Ship Canal and the Cal-Sag Channel and the Lockport Lock; a mid-system alternative of four barriers on CAWS branches between Lockport and Lake Michigan; and a near-lake alternative of up to five barriers closest to the lakeshore. All three include measures to improve the CAWS’s role in flood management, wastewater treatment and maritime transportation, as well as stopping the interbasin movement of aquatic invasive species.

The three separation alternatives in the report were developed by the engineering firm HDR, Inc., which considered some 20 possible barrier locations in its analysis. No recommended alternative is identified. However, one alternative, the mid-system solution, is the least costly and offers other advantages.

The analysis concludes that preventing just a single invasive species from entering the Great Lakes can save as much as $5 billion over 30 years. The Corps of Engineers has identified 10 species that are poised to invade the Great Lakes from the Mississippi River.

According to the report’s economic analysis, the cost of the barriers themselves is as low as $109 million. The addition of all improvements to address water quality, flood prevention and transportation brings the cost to between $3.2 billion and $9.5 billion, depending on the location and the degree to which the wastewater treatment plants on the system are improved to meet future Clean Water Act requirements.

The analysis also finds that households in the Great Lakes basin would have to be willing to pay, on average, about $1 a month from now through 2059 to cover the cost of the mid-system alternative, based on a projected cost of $4.27 billion. The Great Lakes Commission and the Cities Initiative point out that the construction costs to build the current CAWS in today’s dollars would be $11 billion.

Asian carp have been migrating up the Mississippi River system since the early 1990s and were detected in 2009 to have breached electronic barriers operated by the U.S. Army Corps of Engineers in the CAWS. In 2010 a live Asian carp was captured in Lake Calumet just six miles from Lake Michigan.

“The current efforts by the state of Illinois, the Corps of Engineers and others to monitor and slow the carp migration are critical and are buying us time to implement a long-term solution,” said Eder.

“While we recognize and support the work being done by others to find solutions to the Asian carp threat, we need to appreciate fully the urgency of this matter,” Ullrich emphasized.