An invasive species is non-native to the ecosystem under consideration, and its introduction causes or is likely to cause economic or environmental harm. They can also cause harm to human health.
While Colorado is fighting against non-native plants, they are trying to protect their waterways. Currently the Colorado Division of Wildlife has found the invasive zebra mussel in only seven of the state's water bodies; however, they are closely monitoring the state's other 230 bodies of water. Other invasive species that they are trying to prevent the spread of include New Zealand mud snails, rusty crayfish, and aquatic noxious weeds such as the Eurasian watermilfoil. The more bodies of water that these species move into, the more of a chance they have to clog water systems and overtake ecosystems. These invasions could affect the health of the nation's forests, watersheds and rangelands, wildlife, fish, and humans.
It is likely that the zebra mussel moved into Colorado when watercraft transported them from the Great Lakes. They originally came from commercial vessels from Europe. The mussels have no natural enemies in Colorado; therefore, they outcompete native species and form monocultures. The mussels affect the survival of fish by eating the base of the food chain.
The mussels can affect humans by clogging pipes and boat motors, litter beaches, docks, rocks, and underwater features with sharp shells. Because of their damage, billions of dollars go into fixing problems caused by the mussels.
The Lower Colorado River is seeing some of the largest infestations of the mussels aside from the Great Lakes. In order to prevent the spread, the Division of Wildlife is offering free boat inspections. This offer is available at 112 locations in the state. In the past few years about 33 boats coming in from other states had zebra or quagga mussels on them.
"Take nothing. Leave nothing. That includes the critters stuck in the mud in your hiking boots."
See http://www.summitdaily.com/article/20110319/NEWS/110319744/1078&ParentProfile=1055 for more information