A novel dynamic and unified 3D Computational Fluid Dynamics (CFD) model to hydrodynamics studies of waste stabilization ponds is proposed. Two full-scale maturation ponds, at different operational settings, were modelled. This work attempted to consider gaps existing in literature regarding CFD modelling in ponds, such as the real geometric conformation of the accumulated sludge on the bottom; dynamic models representing environmental conditions (wind, solar radiation, air temperature), approximation of the physical properties of the fluid to real conditions, buoyancy etc., all together in a unified model. For validation/calibration purposes, monitoring data were used and experimental tests were performed in the field, using tracers, dyes, temperature and water quality measurements, hydraulic devices and local weather data. Results of field tests agreed well with each other and with the results of the CFD models. From the model proposed, more detailed studies and important analyses regarding the hydrodynamic behavior of ponds could be accomplished, so that interventions to improve treatment efficiency can be better studied and oriented, with low cost and without the need for field or laboratory experiments. The model developed in this study certainly has potential for application in the modelling of ponds in the future, under more realistic environmental conditions. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.