Interesting story. Sounds like different kinds of barriers than those installed in the Chicago River to keep Asian carp out of Lake Michigan.
http://www.startribune.com/stories/462/5463544.html
It's far from a done deal, but natural resource officials are pressing to build two unprecedented fish barriers on the Mississippi River in Iowa to block the upstream migration of Asian carp. The barriers, to be located near Dubuque and Davenport, Iowa, would emit bubbles and sound to deter the carp from entering locks when their gates are open.
Posted by Dave at June 18, 2005 05:38 PM