Keeping Invasive Species Out

​Invasive species—like zebra mussels and round gobies—have forever damaged the Great Lakes. We’re working to keep new ones out.

Once invasive species are established in the Great Lakes, it is nearly impossible to remove them. Preventing them from ever entering is the best way to protect the Great Lakes. We work on two fronts to keep new invasive species out of the lakes:

• Cleaning up ship ballast tanks
• Separating the Great Lakes and Mississippi River basins

Cleaning up ship ballast tanks

In 1959, the St. Lawrence Seaway opened the Great Lakes to direct ocean-going shipping. Unfortunately, the ships brought new, non-native critters along for the ride in their ballast tanks.

Ships need ballast water tanks to stabilize them on long ocean journeys and when loading and unloading cargo. Sixty-five percent of invasive species were released in the Great Lakes when these ships dumped their ballast water.

Cleaning up ballast water is the most effective way to prevent new invasive species in the Great Lakes. The U.S. Environmental Protection Agency and the U.S. Coast Guard teamed up in 2013 to develop new rules for cleaning up ship ballast tanks.

We are keeping a close eye on the two agencies and the U.S. Congress to make sure the laws are implemented as promised.

Separating the Great Lakes, Mississippi River basins

More than a century ago, Chicago undertook a massive engineering feat: the reversal of the Chicago River. But it had unintended consequences that are being felt today.

The man-made Chicago canal connects the Mississippi River to the Great Lakes. It allows invasive species—like invasive carp—to move between the Great Lakes and the Mississippi River basin.

Invasive silver and bighead carp are voracious filter feeders, eating between 20-40% of their body weight in a day. Invasive carp spawn multiple times per year, making them a threat to native species.

The carp are steadily spreading up waterways in Illinois, toward Chicago and Lake Michigan. Invasive carp DNA has been found in the Chicago River in downtown Chicago. Currently the last line of defense is an electric barrier, which according to lab tests, may not be effective at deterring small invasive carp. Barges can also pull fish through the electric barrier.

We’re pushing for a long-term permanent solution to prevent the movement of aquatic invasive species between the Great Lakes from the Mississippi River basin. And, we’re also advocating for improved short term solutions.