Biodrawversity completed a physical, chemical, and biological assessment of 20 lakes and the Housatonic River in Berkshire County, Massachusetts, to determine the presence and potential spread of zebra mussels. Fieldwork included SCUBA diving, plankton sampling and analysis, chemical analysis of surface water, and other techniques to describe the habitat and condition of the target waterbodies. We identified several waterbodies in the region that are at high risk of zebra mussel invasion. We also documented adult zebra mussels in the Housatonic River for the first time ever.