Satellite and in situ cyanobacteria monitoring: Understanding the impact of monitoring frequency on management decisions

•Compared in situ and remotely sensed (RS) in-reservoir cyanoHAB frequencies.•Examined cyanoHABs and reservoir discharge to understand extreme downstream blooms.•In situ and RS monthly cyanoHAB frequencies were strongly correlated.•RS frequencies near reservoir outlet helped explain export to downstream systems.•RS data provided management insights not evident through in situ observations alone.