The use of a sewers-WWTPs-river integrated model allows the efficient minimization of ammonia peaks and oxygen dips in a river Lorenzo Benedetti 1,3) , Pau Prat 2,4) , Ingmar Nopens 3) , Manel Poch 2,4) , Clàudia Turon 5) , and Joaquim Comas 2) 1) MOSTforWATER N.V., Via del Ferrone 88, 50023 Impruneta (FI), Italy 2) LEQUIA, University of Girona, Campus Montilivi, 17071 Girona, Spain. 3) BIOMATH, Ghent University, Coupure Links 653, 9000 Gent, Belgium 4) ICRA, Catalan Institute for Water Research, Carrer Emili Grahit, 101, Girona, 17003, Spain 5) SILSTech, Parc científic i technologic, Universitat de Girona, 17003, Spain. ABSTRACT The Besòs River Basin authority is working towards the implementation of integrated river basin management, as required by the Water Framework Directive (WFD), to achieve a good ecological and chemical status of all water bodies by 2015. The studied system is constituted by two communities (La Garriga and Granollers), their corresponding draining catchments, sewer systems and two WWTPs, which discharge treated water at different locations of the same river. Within this context, the realisation of an integrated model of the river stretch and of the two WWTPs with their sewer systems and draining catchments was necessary. Such a model allows to efficiently simulate and analyse the behaviour of the integrated system and to optimize its performance holistically. In this article, a method is presented to generate rules to be implemented in a supervisory system for automatic management of the Integrated Urban Wastewater System (IUWS) in dry and storm weather. This is achieved by identifying, with the help of Monte Carlo simulations, the most performing operational parameters – according to environmental and economic criteria – for the two weather conditions. A comparison has been made between the simulated actual system management (individual plant operation and with constant operational parameter set) and the one with the supervisory system, showing some improvement in cost reduction and in average concentrations in the river, and substantial improvement of the peak values in the river. Therefore, the model-based optimisation results enable to identify good operational parameter sets values for the integrated management of the IUWS at the Besòs River Basin. KEYWORDS Global sensitivity analysis; integrated modelling; operational parameters; optimisation; scenario analysis; urban wastewater system. INTRODUCTION The Besòs River Basin (1,039 km 2 ) authority (Spain) is working towards the implementation of the Water Framework Directive (WFD), which calls for integrated river basin management of