A fire broke out in a paper mill at around 3.15 pm in a 1,500 m² building housing 2,500 t of paper pulp bales, reels of ‘breaks’ and 200 t of chemicals (used as reactants in the production of paper). Powerless to act against the outbreak of fire, the operator alerted the firefighters who on arrival noted that the fire had spread throughout the whole building. The emergency services removed the chemicals and relocated the combustible products of the neighbouring operator, which were stored in the same building but separated by a 2-hour fire wall. They used significant hydraulic resources (up to 10 m³/s) powered by motor-driven pumps from a diversion channel of the VOLOGNE river. The fire extinguishing water gravity-flowed towards the natural environment and COD, SS, BOD5 and the Standardized Global Biological Index measurements were taken upstream and downstream of the discharge point. A sump device was installed the next day to channel the fire extinguishing water towards the site’s wastewater treatment plant. A firefighter was slightly overcome with smoke. The fire destroyed 3/4 of the building but no chemicals were released during the accident. Due to lack of raw materials, production was suspended for 72 hours. The material damage was estimated at 2 million euros and operating losses at 0.2 million euros. For feedback purposes, it can be added that the metal roof cooled by the firefighters held fast, that the concrete block walls limited heat fluxes to the outside and that the bales of pulp, thoroughly sprayed, swelled then fell causing the storage area’s enclosure wall to collapse. Following the accident, the operator rebuilt the building restructuring the storage areas and revising the fire detection/extinguishing systems, the emergency resources and the water collection system.