Corps changes operations at Lock and Dam 8 to deter Asian carp invasion

The U.S. Army Corps of Engineers, St. Paul District, recently changed how it operates Lock and Dam 8 on the Mississippi River in Genoa, Wisconsin, in an effort to impede the upstream movement of Asian carp.

The Corps changed the way it operates the spillway gates on this site in response to recommendations from a University of Minnesota research team led by Peter Sorensen. The proposed alterations are the result of several years of study of Asian carp movement and deterrent techniques funded by the Minnesota Environment and Natural Resources Trust Fund. These changes were carefully designed to stop carp passage while having minimal effects on native fish, fishing and lock and dam infrastructure.

"Our research has showed that there were small flow imbalances under prior operating procedures that might have been allowing adult carp to swim through the dam," Sorensen said. "Making relatively small adjustments to gate operations will prevent this without affecting barge traffic and costs nothing."

Sorensen explained that the team has also mounted underwater speakers in the lock gates to broadcast low-frequency noises that deter carp but are not known to affect important native species in the river and are not audible to people on the river.

According to the Minnesota Department of Natural Resources, bigheaded and silver carp are now abundant and reproducing in Iowa, about 100 miles south of Genoa and continuing to move north. These fish are known for their voracious food habits and tendency to jump, startling boaters on the Mississippi.

"Lock and Dam #8 is now the only dam on the Mississippi River that has been optimized to reduce carp passage," Sorensen said. "In the future, we hope to make additional adjustments to the gates and lock here and then farther upriver to decrease overall carp passage to just a few percent of present levels which already appear to be low."