Fish can breach an electric barrier in a Chicago canal designed to keep invasive species like Asian carp out of the Great Lakes, according to a new report by the U.S. Army Corps of Engineers. The report, released late Friday, says that barges passing through the canal can facilitate fish passage, and small schools of fish can pass through.
According to the report:
Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength. Additionally, the preliminary DIDSON findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools.
The report comes as the U.S. Army Corps of Engineers is expected to release on January 6 its study on options to separate the Great Lakes and Mississippi River basins. The two iconic waters have been artificially connected by man-made canals built more than 100 years ago.
The artificial connection has allowed invasive species to spread from one ecosystem to the other, wreaking economic and environemtnal harm. Non-native zebra and quagga mussels used the artificial connection to make their way from the Great Lakes—where they were discharged in the ballast of foreign ships—all the way west to California. (Check out this map to see how quickly invasive zebra mussels have spread westward.) Scientists have identified a host of other organisms that could spread via the artificial connection—the most imminent threat being from Asian carp making their way up the Mississippi River.
Conservation groups have urged public officials to more to build a physical barrier to separate the two systems and stop the transfer of invasive organisms. Physical separation is widely regarded as the most effective long-term solution to the problem. The Army Corps’ recent acknowledgement that the temporary electric barrier can be breached only underscores the need for policymakers to move toward building a physical barrier.
The idea to build a physical barrier has already been validated by at least one independent study. An alliance of mayors and Great Lakes states issued a report in 2012 concluding that building a physical barrier is both feasible and affordable. Indeed, such a solution provides a great opportunity for the region to combat invasive species, improve Chicago’s wastewater infrastructure, and better maritime transportation for the region.
The most recent Army Corps report leaves little doubt that it’s time to act. We have solutions. It’s time to use them. The cost of inaction will be devastating to our environment, economy and quality of life.