Two Asian carp species, silver and bighead carp, imported from China in the 1970s, escaped from their pens at fish farms in Arkansas and Kentucky. Disrupting ecosystems thanks to their voracious appetite for plankton and algae that other species need to survive, the carp swam up the Mississippi River, crowded the Illinois River and other regional waterways, and zeroed in on Chicago and the Great Lakes.

To combat these and other invasive species, which could threaten the Great Lakes ecosystem and its $7 billion fishing industries, the resources defense council has proposed physical barriers to separate Chicago waterways and Lake Michigan from the Mississippi. Ms. Gang’s book, “Reverse Effect: Renewing Chicago’s Waterways,” sees the barriers as an opportunity to remake the city’s riverfront.

The barrier proposal, Mr. Henderson said, “is just a step toward advancing the broader discourse.”

But times are tough in the carp-fighting business. State and federal officials say they are controlling Asian carp and keeping them out of the Great Lakes. Anecdotal evidence from a surging carp harvest in the Illinois River seems to indicate that fishing for and selling the carp as food or processing them into fish meal or fertilizer might significantly reduce their numbers, and thus their pressure on waterways in the Chicago area.

In any case, no major action can be taken before the U.S. Army Corps of Engineers releases its comprehensive study into the blockage of aquatic pathways between the Great Lakes and the Mississippi. The findings are due out in 2015.

Given all that, public fears seem at an ebb. Last month, an environmental group in Milwaukee organized what it hoped would be the first anti-Asian carp rally, in a downtown park. Only a handful of people turned out.