Cyanobacterial blooms are expanding around the globe in frequency and intensity. Using cultural models to unravel local meanings, this study explores how stakeholders (fishers, aquaculturalists, and regional experts) from the Nyanza Gulf of Lake Victoria understand cyanobacterial blooms and their impact on human health. The study also examines resource user and expert perceptions of how these blooms have impacted the livelihoods of fishers and aquaculturalists, and how regional experts have responded. Semi-structured interviews (35 total; fishers and aquaculturalists [25], experts [10]) were used to describe cultural models used by different groups. Multiple perceptions of cyanobacterial blooms and their impact on human health emerged, influenced by the social locations of study participants. With the burden of environmental degradation unequally allocated because of dynamic social constructs, these findings reveal the importance of improving the flow of information between those involved in the design and implementation of policies and those impacted by them.