The waters of the Nantes-Brest canal were polluted killing thousands of fishes over an area of 15 km between Carhaix and Châteauneuf-du-Faou. The several tests run on the canal waters and effected fauna did not reveal the nature and source of the pollution. As a safety measures, the inhabitants in question were advised against drinking supplied water momentarily. Water was released (700 l/s) to dilute the pollution. A pumping station stopped talking water samples for a few days. Dams were installed to recover dead fish.