Research note: Recreational boating, sewage production, and potential implications for phosphorus loading in Lake Champlain

Abstract

The impacts of recreational boating on lake ecosystems are often not well characterized, including for Lake Champlain (US/Canada) where excess watershed phosphorus loading drives cyanobacteria blooms. Improperly disposed boater-generated sewage has not been considered as a source of phosphorus in total maximum daily load models or implementation plans for the Lake. Surveys of marinas and boaters informed sewage production estimates by marina-using boaters. Annual boater-generated sewage volume was estimated to range between 2,445 and 5,184 m 3 . These volumes allowed estimation of potential phosphorus contributions to Lake Champlain by improperly disposed sewage at varied rates of discharge. Such contributions were negligible compared to known Lake Champlain phosphorus sources, suggesting use of Clean Water Funds to reduce phosphorus inputs may not be warranted. Nonetheless, due to potential for pathogen contamination, continued financial support through other means was recommended to allow marinas to operate and maintain pumpout facilities at rates reasonable to boaters. Improperly disposed sewage was estimated to represent <0.01% of annual phosphorus contributions to Lake Champlain (USA/Canada). As such, Clean Water Funds targeted to address significant phosphorus inputs to the lake may not be warranted. Nonetheless, continued governmental support for marinas to provide and maintain sewage pumpout facilities for free or at rates most boaters were willing to pay is recommended to minimize introduction of pathogens associated with fecal pollution. To further help ensure compliance with sewage disposal regulations, educational materials and messaging to boaters to encourage use of pumpout facilities should be made available in English and French due to significant populations of boaters speaking each language.