Overview
- The red discoloration on Lake Léman, first reported Wednesday near Anthy-sur-Léman, covered roughly 57,000 square meters.
- Investigators traced the source to a 200‑liter drum of red, water‑based ink lost by a transporter on Tuesday evening in Allinges, with runoff carrying the dye into the Pamphiot river.
- Authorities said the product is not classified as hazardous, and they ruled out recovery operations because only natural dilution in the lake is feasible under supervision.
- By Thursday the surface stain was almost gone, though rocks and the Pamphiot delta still showed residue, and leisure activities such as swimming resumed.
- Firefighters, biodiversity officers, and police documented the scene with drone surveys and opened an inquiry, reflecting the rapid response typical for a shared France–Switzerland freshwater lake where visible changes draw swift scrutiny.