Lakes and reservoirs are aquatic systems that play a crucial role in both environmental balance and human well-being. However, these systems are exposed to eutrophication and deterioration of water quality. Therefore, comprehensive monitoring programs are essential to establish effective strategies for its improvement. The main objective of this study was to characterize an algal and cyanobacteria bloom (HAB) recorded in the Río Tercero Reservoir (Córdoba, Argentina) by integrating In-situ monitoring techniques with satellite-based remote sensing data. Water quality variables and phytoplankton composition were measured in the reservoir and related with a Landsat 9 image. Results revealed the presence of a HAB occurring in the central-western region of the reservoir. This founding was also demonstrated by Landsat data which was used to predict the total chlorophyll-a concentration (Chl-aTotal), and cyanobacterial chlorophyll-a (Chl-aCyano) across the entire reservoir surface.