The literature is full of examples detailing ecological impacts of invasive species and predictions of which and where species will invade next. Many fewer examples of effective prevention strategies are known. Prevention of aquatic invasive species (AIS) to inland lakes should be easily established because most AIS are initially introduced into watersheds by recreational boating activities, especially in North America. The Watershed Management Plan for Otsego Lake, a central New York glacial lake, provides for prevention of AIS via a stringent boat inspection and washing program (BIP). All boats entering Otsego Lake at the public launch are visually inspected and those deemed likely to harbor AIS are required to power wash before launching. However, other sites are available to launch boats. BIP expenses average $30,000 per year, much of which has been covered by collecting a launch fee. After implementation of the BIP, only one boat was refused access, and less than 1% required washing before allowed access, however, zebra mussels (Dreissena polymorpha) and water chestnut (Trapa natans) have since been found in the lake. The BIP continues to be supported because other AIS may have been prevented or may be prevented in the future.