The first version of CASCADE_TOXSWA was realised in 2009. This version was tested with a typical Dutch agricultural landscape in the north-east of the Netherlands in the Klazinaveen-Zwartemeer region. The area, with a size of approximately 10 km², is drained by a network of open drainage ditches with bottom widths between 0.5 and 3 m and a total length of 65 km. The modelled water network consisted of 137 watercourses. The hydrology of the surface water in this area was simulated using the SWQN surface water model (Kruijne et al., 2008). This catchment was also used for coupling of the exposure model CASCADE_TOXSWA to the effects model, MASTEP, a population model for simulating the effects for aquatic organisms (Focks et al., 2013). This first version of CASCADE_TOXSWA covers the entry routes spray drift and drain pipe emission as well as a limited number of processes and, e.g. it does not simulate the fate in the sediment.