Previous to this project a method was developed for sediment quality assessment based on a Triad approach. This Triad method was used to qualify the sediments of small watercourses. The aim of this study is to qualify the sediments of big rivers and channels. The Triad assessment method is based on an integrated evaluation of the chemical, ecotoxicological and biological classification. Finally the sediments of the sampled locations will be divided into four classes, from good to very bad. At the end a good overview will exist of the quality of the sediment in all Flemish watercourses and locations can be chosen that need to be studied more carefully for sanitation. Beside this the developed Triad assessment method can be evaluated and improved, based on the collected data, before it will be used as a regular monitoring tool by the Flemish Environment Agency.