The document discusses developing a GUI for modeling water quality in the Dinkel River using open source tools. It will integrate the OTIS hydro-transport model and FEQ water quality model into a GUI in ILWIS Open. The objectives are to identify appropriate models, couple the models in ILWIS with a GUI, perform calibration and validation, and document a user guide. Preliminary results and work in progress include hydro preprocessing, network splitting, and planned fieldwork. Completion is aimed for March 2010.