To meet the United Nations (UN) sustainable development goals and the European Union (EU) strategy for a nontoxic environment, water resources and ecosystems management require cost-efficient solutions for prevailing complex contamination and multiple stressor exposures. For the protection of water resources under global change conditions, specific research needs for prediction, monitoring, assessment and abatement of multiple stressors emerge with respect to maintaining human needs, biodiversity, and ecosystem services. Collaborative European research seems an ideal instrument to mobilize the required transdisciplinary scientific support and tackle the largescale dimension and develop options required for implementation of European policies. Calls for research on minimizing society's chemical footprints in the water-food-energy-security nexus are required. European research should be complemented with targeted national scientific funding to address specific transformation pathways and support the evaluation, demonstration and implementation of novel approaches on regional scales. The foreseeable pressure developments due to demographic, economic and climate changes require solution-oriented thinking, focusing on the assessment of sustainable abatement options and transformation pathways rather than on status evaluation. Stakeholder involvement is a key success factor in collaborative projects as it allows capturing added value, to address other levels of complexity, and find smarter solutions by synthesizing scientific evidence, integrating governance issues, and addressing transition pathways. This increases the chances of closing the value chain by implementing novel solutions. For the water quality topic, the interacting European collaborative projects SOLUTIONS, MARS and GLOBAQUA and the NORMAN network provide best practice examples for successful applied collaborative research including multi-stakeholder involvement. They provided innovative conceptual, modelling and instrumental options for future monitoring and management of chemical mixtures and multiple stressors in European water resources. Advancement of EU water framework directive-related policies has therefore become an option. © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat iveco mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

An analysis of existing regulatory frameworks for chemicals reveals a fragmented situation with a number of regulatory frameworks designed for specific groups of chemicals; for protection of different end-points and covering different parts of the chemicals´ life cycle stages. Lack of-and fragmented information on chemicals (properties, use, emissions as well as fate, occurrence and effects in the environment) limit the ability for assessment and early action, and existing legislation would benefit from more transparency and openness of information and knowledge. To achieve harmonisation of existing legislation and an efficient control of chemical contamination of European waters, a solution-focused approach is proposed including increased ambitions (in monitoring, modelling, and risk assessment), cooperation and dialogue. More holistic and efficient development and implementation of existing legislation can be achieved by better cooperation, harmonisation and information exchange between different regulatory frameworks and by improved science-policy interactions. The introduction of an organisational structure and incentives for cooperation are proposed. Cooperation should focus on harmonisation of advanced monitoring activities, modelling, prioritisation, risk assessment and assessment of risk prevention ('safe by design') and minimisation options. A process for dialogue and information exchange between existing policy frameworks and with stakeholders (industry, NGO´s, etc.) should be included to identify feasible options for mitigation as well as regulatory gaps-on local and EU-scales. There is also a need to increase international cooperation and strengthen global agreements to cover the full life cycle of chemicals (produced and consumed globally) and for exchanging knowledge and experiences to allow early action. This recommended action would also provide knowledge and a framework for a shift towards a sustainable chemistry approach for chemical safety based on a "safe by design" concept.

Chemical pollution of water bodies is a complex problem around the globe. When described by the extremes of the range of problem definitions, water bodies can be chemically polluted by a single compound that is emitted from a point source or an incidental spill, or by chronic diffuse emissions from local and upstream land uses. The resulting mixture exposures can vary in space and time, e.g. due to the use of pesticides in the crop growing season. The environmental management objectives are commonly to protect and restore surface waters against human influences. Currently, chemical pollution is globally judged for a selected set of compounds, by judging each of these individually in comparison with protective environmental quality standards. Research has provided a novel assessment paradigm (solution-focused risk assessment) and novel data, measurement methods and models to improve on current practices. Their adoption and application require establishing novel linkages between the diverse problem definitions and the novel approaches. That would assist water quality professionals to select the most effective option or options to protect and restore water quality. The present paper introduces the RiBaTox (River Basin Specific Toxicants assessment and management) web tool. It consists of short descriptions of the novel approaches (made available as Additional file 1) and a decision tree for end-users to select those. The overview of novel approaches collated in RiBaTox is relevant for end-users ranging from local water quality experts up till strategic policy developers. Although RiBaTox was developed in the context of European water quality problems, the methods provided by RiBaTox are relevant for users from (inter)national to local scales. This paper is part of a series of Policy Briefs from the EU-FP7 project SOLUTIONS (http://www.solut ions-proje ct.eu), which provide backgrounds on chemical pollution of surface waters and policy practices and proposed improvements.

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