A proposal to prevent the infestation of the Great Lakes by Asian carp faced opposition Sunday when a group organized by Sen. Mark Kirk, R-Ill., gathered on the Chicago River to criticize the plan.

The $18 billion, 25-year proposal is one of many potential approaches to the carp problem that were offered last week in a report by the Army Corps of Engineers.

It would involve physically cutting off Lake Michigan from the Mississippi River through what's known as hydrologic separation _ the use of physical barriers to block aquatic connections between basins.

Such separation would be a blow to businesses that rely on open waterways, said Michael Borgstrom, president of Wendella Sightseeing, a Chicago tour boat company.

"It will sever the artery that supplies the lifeblood to my family's business and about 200 other families of the employees that work at Wendella," Borgstrom said. "Hydrologic separation, in my opinion, is an irrational, costly and irreversible response to something that has been and continues to be successfully managed by federal, state and local agencies."

Del Wilkins, a vice president at New Orleans-based Canal Barge Company, said the barriers would force his company's cargo off the waterways and onto roads and railways.

"Imagine another 25 million tons that are put into rail and truck trafficking," Wilkins said. "If we think we have headaches today, we would have big headaches tomorrow."

But others who reviewed the report said it's too soon to know how river traffic might be affected by such barriers, which would take many years to erect.

"Everybody understands that making Illinois' and Chicago's economy worse is a nonstarter," said Joel Brammeier, president of the Alliance for the Great Lakes, a nonprofit environmental group.

It's unlikely that state and city officials will back a plan that would block tour boats from being able to access Lake Michigan and the portions of the Chicago River where tours are popular, Brammeier said.

He acknowledged that the barriers could impede freight routes but argued that those routes have lost significance in recent years. A 2011 Army Corps study found that cargo traffic on Chicago-area waterways was flat or declining over a 15-year period.

"Standing up and saying that these waterways are going to work the same as they have for 120 years and 'full steam ahead' is the equivalent of burying your head in the sand while carp is flowing up the river and into Lake Michigan," Brammeier said.

Last week's Corps report was commissioned by Congress after scientists discovered genetic material of Asian carp near Lake Michigan. The fish has no natural predators and a voracious appetite. It's known as the "river rabbit" because of its rapid pace of reproduction.

The Corps studied the problem and came up with eight potential approaches for keeping carp and other invasive species out of the Great Lakes. Four of the options would use hydrologic separation and are estimated to cost between $8 billion and $18 billion. Kirk said the proposals would cost too much and are unnecessary. He favors increasing the voltage at existing electric barriers designed to keep the carp out. The Corps reported last month that the barriers can sometimes be breached by fish.

"I would hypercharge the electric barrier to make sure that it is 100 percent effective," Kirk said, noting that he was told by a Coast Guard official that voltages were kept low because boat passengers could be shocked if they touch the wall near a barrier. That problem could be solved with proper signage, Kirk said.

"No need to keep the voltage low because some bureaucrat in Washington wants to keep it low," Kirk said. "We should keep it high to make sure it's very effective."

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