Every year around 50 tonnes of plastic ends up in Lake Geneva, according to study mandated by the Association pour la sauvegarde du Léman (ASL).
Most plastic comes from litter and from plastic in rivers flowing into the lake.
Only 10% of this total plastic leaves the lake via the Rhone river. The rest remains there with a small amount removed manually.
60% of the plastic that ends up in rivers is plastic fragments that wear off vehicle tires, which are washed into rivers and streams. Litter and packaging makes up another 20%, construction rubbish a further 7%. The rest is micro plastics from washing synthetic clothing (4%), road paint (2%), cosmetics (1%), industrial plastics (1%) and a variety of other sources (5%).
Most of this plastic ends up in lake sediment and some in fish and other fauna.
ASL, which organises volunteers to remove large pieces of plastic rubbish from the lake, calls on residents to limit the use of single-use plastics and use reusable products instead. Reusable bottles for water and coffee can make a big difference over the course of a year. Plastic bottles and other plastic litter eventually break down into micro and nano plastics if left in the lake, it said.