Waterschapsbedrijf Limburg contracted Aqua Vision to perform depth measurements in the aeration tanks of two waste water treatment plants in the towns of Hoensbroek and Venlo. These measurements were carried out in the summer of 2016 using the RiverBoat ADCP and the ViSea Quad Beam Toolbox software. Results clearly show the bathymetry of the aeration tanks, containing details such as aeration tubes and accumulation of sludge in certain places. Results like these can help companies optimize the maintenance of their sewage treatment facilities.