Sediment represents an important compartment in surface waters as it constitutes a habitat or spawning site for many organisms and an essential trophic resource for higher trophic level organisms. It can be impacted by anthropogenic activities, particularly through urban wet-weather discharges like stormwater and combined sewer overflows. An approach is presented for assessment for assessing the risks caused by urban wet-weather discharges to the sediment compartment based on total suspended solids (TSS). TSS is a standard parameter measured in field surveys and can be considered as a tracer for urban wet-weather contamination. Three assessment criteria linked with TSS are proposed: a) siltation of the riverbed, b) oxygen demand due to organic matter degradation and c) accumulation of ecotoxic contaminants on the riverbed (heavy metals, PAHs). These criteria are translated in terms of the maximal TSS accumulation load and exposure time (percentage of time exceeding the accumulation criteria) to account for the dynamics of sediment accumulation and resuspension in streams impacted by urban wet-weather discharges. These criteria were implemented in a stochastic model that calculates TSS behavior in receiving waters and allows therefore an assessment of potential impacts. This approach was applied to three Swiss case studies. For each, good agreement was found between the risk predictions and the field measurements confirming the reliability of the approach