Progress Illinois talked to members of the U.S. Army of Engineers team responsible for helping protect Chicago's waterways from invasive species, like Asian carp.
In a recent PI article
on Chicago’s waterways, we discussed the threat Asian carp present to the
future health of Lake Michigan. The US Army Corps of Engineers (USACE) reached out to discuss
their current strategy, future efforts, and the importance of public
awareness in preventing the Asian carp from entering Lake Michigan.
US Army Corps of Engineers team:
Progress Illinois: Would you summarize the USACE strategy to prevent Asian carp from entering Lake Michigan?
U.S. Army Corps of Engineers: The USACE utilizes a four-prong strategy including the electric fish barrier system; extensive monitoring of the Chicago Sanitary and Ship Canal; efficacy studies on how to better the system; and a holistic program called GLMRIS, which stands for the Great Lakes and Mississippi River Interbasin Study. Monitoring has found 2.7 million detections of the species downstream, but no carp have crossed the electric barriers.
PI: How does the electric barrier work?
USACE: The barrier puts electric current in the water, and the fish will feel a tingle as they approach. The fish will become increasingly uncomfortable and will turn downstream as they get closer to the current. There are three barriers constructed but only two are active. Barrier I is a demonstration barrier with a field strength of one volt per inch. Barriers IIA and IIB have a field strength of 2.3 volts per inch and can be operated at any time. The demonstration barrier is located further upstream (closer to Lake Michigan).
PI: How do you respond to criticism from organizations such as the Natural Resources Defense Council that the electric barrier system cannot prevent very small fish from moving upstream?
USACE: Laboratory research indicated that previous setting of two volts per inch may not defer small fish. We tested fish down to two inches in length and determined that field strength would be increased in October 2011. Additionally, we fitted fish as small as 2.1 inches with electric transmitters and they have not been found past the barriers.
PI: Does the presence of environmental DNA (eDNA) indicate, as some environmental groups claim, that Asian carp have surpassed the barriers?
USACE: It’s always important to make the distinction between eDNA and live fish. When we collect samples we are testing for genetic materials. We don’t know how this genetic material got there, [or] whether it’s from a live fish. What does it mean? There are other ways for eDNA to get there. Maybe from a bird that ate a piece of Asian carp, from fish swimming downstream or maybe even from street vendors in Chinatown dumping ice into the sewer.
DNA can stay in water for a long time so we have to be careful. It’s important to note that in Chicago waterways, our monitoring and rapid response workgroup uses a range of information, but eDNA is a trigger. We don’t really know what it means yet so we error on the side of caution. All of our response actions on eDNA have yet to lead to a live fish capture.
PI: What is GLMRIS?
USACE: GLMRIS is a long-term look at the transfer of aquatic nuisance species between the Great Lakes and the Mississippi River. The purpose is to look at a long-term solution to prevent future transfer. This, of course, includes the Asian carp, but also past species transfer such as zebra mussels and the round goby.
PI: The GLMRIS website indicates that the study may not be complete until 2015. How will USACE respond to new developments over the next three years?
USACE: It’s important to remember than GLMRIS is the fourth part of the overarching strategy, which of course includes the electric barriers. Before the study is complete, there will be construction of permanent barriers to provide redundancy and extra protection. The new barriers will have the same potential to defer fish as Barrier II. An efficacy study identified the need for a barrier along the Des Plaines River to prevent fish transfer between the Des Plaines and Chicago Area Waterways during flood events. A comprehensive efficacy study will be completed this year and will recommend strategies for the Grand Calumet and Little Calumet Rivers. We’re not just going to maintain status quo. US Army Corps of Engineers is only one agency within a greater holistic picture of federal agencies and the Asian Carp Regional Coordinating Committee. We stress that the partnership at all levels is ongoing. Our efforts are coordinated with state and municipal agencies.
PI: Where does USACE stand on the issues of hydrological separation?
USACE: Hydrological separation means the permanent stoppage of water between the Great Lakes and Mississippi River. There are over 90 specific individual controls available and hydrological separation is only one option. We’ll evaluate that as the process continues.
PI: What can the average person do to help prevent Asian carp from entering Lake Michigan?
USACE: People should educate themselves on the issues. We use a very transparent process and make a lot of information available to the public. People should stay cognizant that there are alternate means by which Asian carp can move between the Chicago waterways and Lake Michigan, including bait buckets and ballast water. The human transfer of Asian carp is a threat. The barrier is working but people must be aware of the issues. They should be on the lookout and maintain proper precautions to make sure there are not human methods of transfer.
Asian carp resources:
US Army Corps of Engineers Aquatic Nuisance Species Portal
Great Lakes and Mississippi River Interbasin Study
Asian Carp Regional Coordinating Committee