According to the U.S. Environmental Protection Agency, Otisco Lake is affected by nonpoint source pollution from agriculture, residential land use and streambank erosion. Pollution from these sources includes pesticides and fertilizers, sedimentation from erosion and poor tillage practices, and runoff from septic systems, lawns and construction sites.[1] Currently the lake is experiencing severe problems brought on by zebra mussels which were introduced to the lake water via boaters.