The Obama administration proposes spending $475 million to clean up the Great Lakes.
The amount represents the first step in a multiyear cleanup that also would try to prevent foreign species of plants, fish and other animals from entering the Great Lakes system.
The federal Environmental Protection Agency reports at least 25 nonnative species of fish have entered the Great Lakes since the 1800s.
Numerous aquatic plants also have made their way into the lakes. The invading plants replace native vegetation that provide food for wildlife and erosion control.
Here's a sampling of some of the invasive species found in Lake Ontario.
Zebra mussels:Introduced in 1988, zebra mussels have spread throughout the five great Lakes and into tributaries. The mussels have caused problems at power plants and municipal water supplies, clogging intake screens, pipes and cooling systems. They have also nearly eliminated the native clam population in the ecosystem.