An ensured supply of drinking water is a major purpose of water reservoirs. The input and accumulation of sediments and nutrients in the reservoir body can cause strong growth of algae and cyanobacteria which leads to significant quality-related use restrictions. Continuous monitoring of the reser-voir water quality can help to indicate such trends at an early stage. Small and lightweight cameras are promising to be used on UAV platforms as close range remote sensing system of water reservoirs. We present the set up of such a monitoring system which main elements are a hyperspectral camera and a thermal infrared imaging sensor on a UAV and show first results from a field campaign at the Passaúna reservoir close to Curitiba, Brazil.