Pollution of the Rhône river was noted at around 4.00 a.m. in the vicinity of a paper mill. The product spilled consisted of lignite (derived from wood) and caustic soda.

The pollution spread along a length of 13 km and across two-thirds of the width of the Rhône. However, no aquatic wildlife mortality was observed.

The operator put in place an action plan to treat pollution at source: heightened surveillance of the waste water treatment plant and injection of an anti-foaming agent.

The primary cause of the accident seems to have been a malfunction in the site’s waste water treatment plant. The causes are under investigation.