Surface water quality management requires foresighted decision making regarding long-term investments. It should consider multiple objectives (e.g. related to different pollutants and costs), integrate multiple sources of pollution (point and diffuse sources), and external conditions that change over time (climate, population and land-use changes). Multi-attribute value theory can support such decisions, especially the development of an assessment method. Integrated surface water quality assessment methods including micropollutants are currently lacking or in development in many countries. Important steps for the development of such an immission oriented and integrated surface water quality assessment method are discussed in this paper and exemplified for organic micropollutants. The proposed assessment method goes beyond simple pass-fail criteria for single substances. It provides a continuous assessment on a scale from zero to one based on five color-coded water quality classes and suggestions for the visualization of assessment results. It takes into account the toxicity of the micropollutants and their mixture to aquatic organisms by comparing measured concentrations to environmental quality standards (EQS). The focus of this paper is on aggregation over multiple substances and time. Advantages and disadvantages of different aggregation methods are discussed as well as their implications for practice. The consequences of different aggregation methods are illustrated with didactical examples and by an application of the proposed water quality assessment method to pesticide monitoring data from Switzerland. Recommendations are provided that account for the purpose of the assessment. Furthermore, the paper illustrates how the proposed method can facilitate dealing with uncertainty and a transparent communication of monitoring results to support water quality management decisions.

地表水质量管理需要就长期投资做出有远见的决策。它应考虑多个目标（例如，与不同的污染物和成本有关），整合多种污染源（点源和分散源），以及随时间变化的外部条件（气候，人口和土地利用的变化）。多属性价值理论可以支持此类决策，尤其是评估方法的发展。许多国家目前缺乏或正在开发包括微污染物在内的综合地表水质量评估方法。本文讨论了开发这种面向排放的综合地表水质量评估方法的重要步骤，并以有机微量污染物为例进行了说明。所提出的评估方法超出了单一物质的简单通过/失败标准。它基于五种颜色编码的水质等级，提供了从零到一的连续评估，并提供了可视化评估结果的建议。通过将测得的浓度与环境质量标准（EQS）进行比较，考虑了微污染物及其混合物对水生生物的毒性。本文的重点是在多种物质和时间上的聚集。讨论了不同聚合方法的优缺点及其对实践的启示。通过教学示例和将拟议的水质评估方法应用于瑞士农药监测数据中，说明了不同汇总方法的后果。提供了用于评估目的的建议。此外，本文还说明了所提出的方法如何能够促进不确定性的处理以及监测结果的透明通信，以支持水质管理决策。