This article presents a novel autonomous surface vessel (ASV) that was designed and manufactured specifically for the monitoring of water resources, resources that are not only constantly drained but also face the growing threat of mass proliferation (bloom) of noxious cyanobacteria. On one hand, the distribution of these blooms in a given water body requires a surveillance of biological data at high spatial resolution on both vertical and horizontal axes, whereas on the other hand, the understanding of the temporal evolution of the cyanobacteria necessitates repeated sampling at the same location. Therefore, our ASV was designed to combine the ability to take measurements within a range of depths, with its custom-made winch, and accurate localization provided by the global positioning system (GPS), without the need for static installations. This article first describes the ASV conception, and then the results of extended field tests on the waypoint navigation mode are discussed. Finally, the first results of a sampling campaign for monitoring algal blooms in Lake Zurich are presented. This work constitutes advances in the deployment of mobile measurement platforms for environmental monitoring in lacustrine environments. Furthermore, it investigates the application of a single ASV to capture both spatial and temporal dynamics of harmful cyanobacterial blooms in lakes. Combining surface mobility with depth measurements within a single robot allows fast deployments in remote location, which is cost efficient for lake sampling. This reduces the need for fixed installations, which can be impossible in recreational areas. The high-resolution sampling of lakes will contribute to understand and predict the occurrence of harmful cyanobacterial blooms for a better management of water resources.