Evaluation de l'impact des rejets de déversoirs d'orage par analyse de la colonisation de substrats artificiels par la macrofaune benthique et les diatomées Assessing the impact of discharges from combined sewer overflows through analysis of the colonization of artificial substrates by benthic macrofauna and diatoms

Impact evaluation of a combined sewer overflow in wet weather (SRUTP) in a small stream has been tested for two consecutive years, from the colonization of artificial substrates by the two biological indicators most commonly used (macro benthic fauna, and diatoms). Comparative analysis of the inventories obtained upstream and downstream of the discharge were made with IBD and IPS for diatoms and by general principles of IBGN and BMWP Score for macro-fauna. Both indicators have well served to highlight the impact of the discharge. The use of colonization capacity of artificial substrates by macro-benthic fauna, however, proved best suited to appreciate the importance and interpretation of inventories according to the principle of BMWP Score to better quantify the differences upstream - downstream.