Hydrocarbons from a collector of rain water polluted the JARD river and the pond of AMAURY (aquatic base).Oil booms prevented the pollution from spreading and facilitated pumping operations and the use of absorbent. All aquatic activities were suspended for a few days. The pollution occurred due to the malfunctioning of an oil trap in an automobile equipment manufacturing plant during a storm, as well as due to the inappropriate configuration of the sewage network supplying the urban wastewater treatment plant whose storm overflow is connected to the JARD river. The waste outlet of the plant was connected to the rain water network. A new decanting device/oil separator was installed and 15 tonnes of sludge/hydrocarbons were removed from the rain water collector.