On 16 September, climate activists from the Strasbourg branch of Extinction Rebellion poured organic green dye into the Lauch River, one of the French tributaries of the Rhine. They did this as part of a publicised protest over the use of the disused Stocamine mine in Alsace as a landfill site.

The disused potash mine is already filled with 42,000 tonnes of toxic waste, such as arsenic, asbestos and chromium, according to Le Monde. It is estimated that as much as 25% of the harmful substances at Stocamine are water-soluble.

The toxins pose a risk of contamination of the Alsace, the largest aquifer in Europe. Activists are demanding that the authorities remove the toxic waste before the mine becomes inaccessible due to geological processes taking place underground.

The mayor of the French municipality of Colmar, located on the Lauch River, published a photo of a dead fish in green water on his social media page. In the description of the post he wrote: "I have been notified by residents of the presence of dead fish in the Lauch following pollution caused by the environmentalists".

The case was picked up by conservative media and online commentators, not only in France but all over the world. Despite the fact that the river was already dyed three days ago, still the only illustration of the harmfulness of this action is the same photo of one dead fish.

Could the green dye really harm the river's fauna? This of course needs to be clarified. However, it is worth mentioning that it is assumed to be non-toxic to both animals and plants.

The same dye has been used for decades to dye the water green for St Patrick's Day in Ireland and the USA. As we can read on enjoyillinois.com, in Chicago it was environmental activists who convinced the authorities in the 1960s to replace the dye with a non-toxic, plant-based ingredients.