Patterns and impacts of cyanobacteria in a deep, thermally stratified, oligotrophic lake

Cyanobacterial blooms are a concern in oligotrophic lakes because these systems are often used for multiple purposes (i.e., recreation and public water supplies). Monitoring cyanobacteria impacts is challenging in such cases because of low and heterogeneous concentrations over time, space, and depth. Canandaigua Lake (New York State) is oligotrophic, but has been impacted by blooms since at least the early 2000s, with limited quantification. This study integrated data from established shoreline surveillance and inter‐agency monitoring programs to connect lake processes and evaluate use impacts. Surveys at open‐water locations were conducted to investigate the origination, timing, and magnitude of cyanobacterial bloom development. Impacts on recreation and source water were caused by blooms originating in the epilimnion that moved to shorelines and intake depths. The integration of multiple monitoring programs was critical to understanding impacts. The methods developed here can be adopted to other cases of large, deep, low‐nutrient lakes.