The front-range Colorado reservoir at Pueblo will be closed until proper inspection and decontamination procedures are implemented.
Denver Water said it takes the threat of this aggressive non-native species very seriously.
Zebra mussels 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.
The water board said that boat inspections are needed to maintain the integrity of the state’s boating and fishing communities, as well as water quality.
Denver Water said it 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.
Zebra mussels can clog pipes, valves, gates and any water-related equipment or surface. They can ruin boats by jamming equipment and causing motor damage, and they destroy fisheries by consuming nutrients and wrecking the food chain.
Antero Reservoir Closed
US - Denver Water has temporarily closed Antero Reservoir following the discovery of zebra mussels.