With the increase in beaver impacted waterways in the ten years following the adoption of the Anti-Trapping referendum in 1996, and the introduction of West Nile Virus 1999; concern over mosquito breeding in these waterways also increased. The purpose of the study was to determine the effects that permanent organic structures have on mosquito breeding. Beaver impacted waterways were evaluated to determine where and when breeding takes place within the system. In addition, overwintering conditions were evaluated to determine the potential for beaver lodges to act as hibernacula for adult mosquitoes. The results suggested that waterways with abandoned beaver lodges had a greater chance of increased mosquito breeding versus waterways with active beaver lodges.