Towards an integrated surface water quality assessment: Aggregation over multiple pollutants and time

Area of Science:

• Environmental Science
• Water Resource Management
• Ecotoxicology

Background:

• Effective surface water quality management demands foresight, integrating multiple objectives, pollution sources (point and diffuse), and dynamic external factors like climate and land use.
• Current integrated surface water quality assessment methods, particularly for micropollutants, are often underdeveloped or absent globally.
• Multi-attribute value theory offers a framework for complex decision-making in water management.

Purpose of the Study:

• To outline key steps for developing an integrated, immission-oriented surface water quality assessment method, exemplified by organic micropollutants.
• To propose a continuous assessment scale (0-1) with color-coded classes and visualization tools, moving beyond simple pass-fail criteria.
• To evaluate different aggregation methods for multiple substances and time points, considering toxicity and environmental quality standards (EQS).

Main Methods:

• Development of a novel assessment framework based on multi-attribute value theory.
• Integration of toxicity data by comparing measured micropollutant concentrations against established environmental quality standards (EQS).
• Analysis and comparison of various aggregation techniques for temporal and substance-specific data, using pesticide monitoring data from Switzerland.

Main Results:

• A continuous, color-coded water quality assessment scale (0-1) was developed, incorporating toxicity and mixture effects of micropollutants.
• The study evaluated aggregation methods, demonstrating their impact on assessment outcomes through didactical examples and real-world data application.
• The proposed method facilitates handling uncertainty and enhances transparent communication of monitoring results.

Conclusions:

• The developed assessment method provides a robust tool for integrated surface water quality management, addressing complex, multi-faceted challenges.
• The approach supports informed, long-term investment decisions by offering a clear, continuous, and visually interpretable assessment of water quality.
• Recommendations are provided for practical application, emphasizing the importance of aggregation methods and transparent communication in water management.