In 2008, several lakes in Colorado, USA, including lakes Pueblo and Grandby were identified as infested with dreissenid mussels (i.e. zebra and quagga mussels, respectively).  To aid in the management of the lakes and reservoirs of Colorado models were developed to predict the spread and habitat suitability of dreissenid mussels throughout Colorado, specifically: 1) The potential habitat suitability was predicted for the lakes and reservoirs in Colorado by identifying the water quality of these lakes and comparing these values to known lakes with dreissenid mussels, and 2) Developed a dispersal model of zebra mussels based on the movement of recreational boaters and river and canal/pipe connections.  The dispersal of recreational boaters was modeled using a production-constrained gravity model and parameterized using survey data.  The model focuses on the movement of Colorado boaters and determines the potential of boaters to first travel to a dreissenid infested lake and to make a second trip to uninfested lakes.

Results/Conclusions

The model results suggest that most of the reservoirs east of the continental divide are considered suitable for zebra mussels.  West of the divide is more variable.  The central mountain region is the primary area where zebra mussels are not expected to be able to establish, but the southwest also appears to be suitable. The gravity model results predict that Neenoshe Reservoir has the highest probability of being infested with zebra (or quagga) mussels due to overland transport, while John Martin Reservoir is most at risk to downstream dispersal.  The model also predicts that the zip codes of Grand Junction, Pueblo and Colorado Springs have the highest probability of spreading zebra mussels between lakes.  This is particularly true for Pueblo, which is near the infested Pueblo Reservoir and for Grand Junction, which is relatively close to the Colorado River reservoirs of Powell, Mead, etc., which are infested with quagga mussels.   These model results will be continually updated as more data about the current state of dreissenids in Colorado becomes clear.  These results are currently being used to develop the State of Colorado’s management plan.