Zebra Mussel Fact Sheet

Zebra mussels — an aggressive aquatic non-native species — have been detected in a front-range Colorado reservoir (Pueblo) and pose a high threat of spreading to other reservoirs and waterways throughout the state. The primary threat in Colorado is zebra mussel movement through recreational boating, as the mussels can easily “hitchhike” by attaching themselves to boat hulls, trailers and aquatic plants and animals.

Denver Water takes the threat very seriously and has made some changes to procedures at Denver Water-owned reservoirs in response.

Denver Water is sensitive to the economic impacts associated with closing its reservoirs and is working closely with State Parks, the Colorado Division of Wildlife and other entities to put systems in place to conduct inspections on all boats before they are cleared to enter a reservoir and provide mobile decontamination units to clean boats that are found to be infected. The agencies are working together to determine the next steps for other Denver Water-owned reservoirs where boating takes place, prior to the regular opening dates for boating.

Additional Zebra Mussel Facts:

• Zebra mussels clog pipes, valves, gates and any water-related equipment or surface.
• They can ruin boats by jamming equipment and causing severe motor damage.
• Each mussel filters one quart of water a day, stripping natural habitats of the nutrients that aquatic life needs to survive. In other words, they destroy fisheries by consuming nutrients and wrecking the food chain. They also can harbor e.coli and botulism, harming bird populations, as well.
• Zebra mussel larvae are microscopic, which is why boats have to be cleaned, drained and dry to ensure they will not contaminate other waters.
• The mussels grow and spread very rapidly. An adult female zebra mussel can release up to 1 million eggs each season.
• Zebra mussels are native to the Black and Caspian seas in Europe, and migrate to and from bodies of water through stream corridors.
• Zebra mussel infestation is epidemic in the eastern and northeastern parts of the United States, particularly in Minnesota and Wisconsin. Billions of dollars in damage has been caused to water utility facilities, boats and marinas.
• There is no effective way to rid a body of water of these mussels without negatively impacting water quality.

For more information, visit

• Colorado State Parks: Zebra Mussels
• Colorado Division of Wildlife: Invasive Species
• 100th Meridian Initiative
• Protect Your Waters
• Aquatic Nuisance Species (ANS) Task Force