The US has been battling invasive carp for almost 50 years, but they are thriving in the Mississippi River and other waterways. Catching them is not hard, they just jump into the boat. But as carp multiply their way closer to the Great Lakes, where they could wreck the balance of native species, we've had to pull out the big guns. The US Army Corps of Engineers built a series of "fences" by electrifying the water in canals leading to Chicago in order to stop the traveling carp from entering Lake Michigan. This electrified water is serious business and canal traffic has to adhere to strict rules to keep people from danger.