Water pollution by chemicals (e.g. persistent organic pollutants) impacts biodiversity as well as human health, economy and life quality. With the increase of population and human activities, it has become an urgent security issue. By introducing the water pollution-related traces into an intelligence process, we are convinced that forensic science can support authorities in decision-making to tackle this security issue. By taking the example of the Lake Geneva basin, this study identifies the limitations of current approaches to monitor chemical pollutants (hardly comparable data, insufficient sensitivity and low temporal representativeness). To overcome these limitations, a passive sampling-based acquisition process was elaborated. Relevant features were extracted (concentrations, loads and ‘chemical signatures’ of pollutants) and enabled pattern detection. The analysis of these patterns in combination with alternative information (e.g. field knowledge from environmental agencies) resulted in intelligence products that can support authorities in preventing current chemical releases from being repeated (or continued) or similar releases from being committed.