TAPAS partner Wageningen Environmental Research (Alterra) organized a workshop in Wageningen at the end of October 2016 as part of the work package (WP3) that dealt with the environmental risk assessment of potentially toxic substances. The first aim of the workshop was to evaluate existing models for the environmental risk assessment of chemicals used in aquaculture in the EU and to design a strategy for their development and improvement. During the workshop the pros and cons of the modelling approaches described in the review were discussed and a preliminary (set of) modelling tool(s) that better allow the evaluation of environmental impacts of chemical used with the current EU regulatory framework was selected. A second aim of the workshop was to get an overview of the systems and facilities that the various TAPAS partners can provide for the (experimental) case studies to be used by the various work packages in the TAPAS project and to select, specifically for WP 3, the four experimental sites used to carry out experimental studies for the calibration and evaluation of the different components of the modelling tools selected/improved. It was concluded that it is vital to take in to account multiple stressors (e.g. chemical and nutrients combined). Therefore, modelling of exposure to chemicals together with nutrients is required. Close collaboration between WP3 (chemicals), WP5 (nutrients) and WP 7 (case studies) is needed and it was agreed to organise in conjunction with WP5 and WP 7 a meeting in early spring 2017 to discuss and make detailed protocols in order to align the case study designs and experiments.