Casting the Dye

Reports that the police have dyed the waters of the Blue lagoon on Hurpur Hill, Buxton black are disturbing (https://www.derbyshiretimes.co.uk/health/coronavirus/police-dye-water-buxton-blue-lagoon-deter-swimmers-during-coronavirus-lockdown-2521350). I can appreciate that, in these days of the Covid-19 pandemic, they would want to deter reported groups of swimmers from gathering in the location but, even if the dye is harmless to humans, one cannot be sure that the chemical or its obscuring effects would not be detrimental to other animals and plants in and around the pool. If this had been done by anyone else, it would have been classified as vandalism or a polluting event.