Understanding freshwater ecosystems is essential for their conservation and restoration. Within these systems, the sediment is of major concern due to its role in pollutant accumulation and the inherent risk of the remobilisation of those contaminants after either natural or anthropic perturbation. Such impacted sediments have an important functional role through, for instance, their effect on their associated macroinvertebrate assemblages. Lentic systems and in particular sediments have to date not been well studied especially in context of metal contamination. Thus within storage systems there is currently a need for the development of a contextual framework of biomonitoring tools for contaminated sediments. The objective of this study is to assess the impact of contaminated sediments by comparing environment data, macroinvertebrate taxonomic composition, functional diversity, and other biological and ecological traits from sediments with varying degrees of contamination. Initial results suggest that diversity indices fail to discriminate the impact of metals on these macroinvertebrate communities but that measures of functional diversity might be more useful. Our study also indicates that the impact of contamination cannot simply be detected from environmental data or by the analysis of faunistic structure. We thus question the relevance of using multimetric tools in freshwater studies and suggest that the application of multivariate approaches to functional diversity may be more effective in discriminating the effects of metal contaminants.