This dataset includes the data obtained during the installation of a camera system to determine the surface velocities in a retention pond monitored by Aalborg University (AAU). The dataset consists of raw and processed images and surface velocity maps obtained during preliminary experiments when the retention tank was being filled and emptied. The objective is to assess the feasibility and usefulness of this type of measurement for the calibration of CFD models to optimize the operation of the installation. The data presented may help to improve and assess imaging techniques in real conditions in urban environments. The dataset is a result from the Joint Research Activity 3 (WP8, Improving Resilience and Sustainability in Urban Drainage solutions), Task 8.3.1. (Hydrodynamic design for stormwater detention ponds optimized for cost-efficient maintenance) within Co-UDlabs project, funded under the European Union's Horizon 2020 research and innovation program under grant agreement No 101008626.