An outbreak of Botulism Type C occurred in waterfowl at Smith and Bybee Lakes in Portland Oregon during the fall of 2012. Initiating factors included low water leves, high waterfowl density, and warm air and water temperatures. Preliminary diagnosis was made based on clinical signs of progressive paralysis, and a lack of gross lesions on necropsy. A definitive diagnosis was made using the mouse bioassay to confirm type C botulism. Treatment of affected animals was by supportive care. Mitigation was used to attempt to minimize the effects of the outbreak. Carcass collection, lake draining and harassment were used. The outbreak ended at after 2 months with over 2500 carcasses collected, mostly of resident waterfowl.