Chemical pollution in surface waters is one of the major threats to aquatic ecosystem functioning and health. However, it appears impossible to analytical analyse the whole pollutant universe and their transformation products present in surface waters and mixture effect may be overlooked. Therefore complementary methods are needed that overcome those analytical problems. Effect-based monitoring tools can be an important step in monitoring programs to link chemical and ecological information and improve the environmental relevance. In this project we will start with evaluating and explore an optimal choice of (available) effect-based tools at various levels of biological organization. These effect-based monitoring tools will include bioassays (in vitro and in vivo) and microbial biomarkers expected to be useful in linking chemical with ecological assessment in aquatic monitoring. Next, the selected effect-based monitoring tools and innovative sampling tools including passive sampling techniques will be evaluated in microcosms and mesocosms exposed to relevant emerging contaminants alone and in mixtures. Based on these results, we will select the most promising effect-based tools and design a bioanalytical test battery for water quality monitoring and assess ecological health risks at representative sites of surface water in the Netherlands.