FOCUS surface water scenario help (SWASH) Version 1.1; user's guide Version 1.1

The user-friendly shell SWASH, acronym for Surface WAter Scenarios Help, assists the user in calculating pesticide exposure concentrations in the EU FOCUS surface water scenarios. It is part of the exposure calculation procedure developed by the FOCUS Surface Water Scenarios Working Group, which has become part of the obligatory evaluation procedure to place an active substance on List 1 according to EU Directive 91/414/EEC. SWASH encompasses four separate tools and models: (i) FOCUS Drift Calculator, calculating pesticide entries through spray drift deposition, (ii) PRZM-3, calculating pesticide entries through run-off, (iii) MACRO, calculating pesticide entries through drainage and (iv) TOXSWA, calculating the behaviour of pesticides in small surface waters. It maintains a central pesticide properties database, prepares input for the PRZM, MACRO and TOXSWA models and then guides the user in performing the FOCUS Surface Water runs in a consistent and user-friendly way. Via the SWASH shell the user can enter the shells of the other models to perform the PRZM or MACRO model runs needed to assess the fate of the substance in the FOCUS water body systems using TOXSWA