The aim of this paper is to highlight a not yet recognized hazard for mass failure (landslides) of contaminated soils into rivers and to provide an understanding of important interactions of such events. A first effort to investigate the problem is made focusing on the south eastern part of the Göta Älv river valley, in Sweden, by combining geographical information on potentially contaminated sites with slope stability levels on maps. The objectives of this study were to: (1) Review current Swedish risk assessment methodologies for contaminated areas and landslides, and analyze their capability to quantify the risk of contaminated areas being subject to landslides. (2) Investigate the presence of contaminated areas at landslide risk along the Göta Älv river valley. (3) Provide an overview of the national methods for landslide risk analysis and for environmental risk classification, followed by a comparison between the methods and the results from the superposition of the two methods for the study site. (4) Make a first attempt to conceptualize the release and transport mechanisms.