Retention–detention basins are important structures for managing stormwater. However, their long-term operation raises the problem of managing the sediments they accumulate. Potential uses for such sediments have been envisaged, but each sediment must be characterised beforehand to verify its harmlessness. In this paper we address this issue through the development of a battery of bioassays specifically adapted to such sediments. We tested the method on samples taken from four retention basins in the region of Lyon (France). This battery focuses on the toxic effects linked to both the solid phase (ostracod and Microtox® solid-phase tests) and the liquid-phase (interstitial water) of sediments (rotifer and Microtox® liquid-phase tests). The results obtained permit the sorting of sediments presenting little toxicity, and which could therefore be potentially exploitable, from those from more polluted areas presenting higher toxicity that limits their use.