Dyeing the Countryside

I worry about the news that Derbyshire police put dye in a lake to make it unattractive to visitors.

Dyes are complex chemicals that need to be handled with caution. People often wear protective clothing when using them. Could water from the lake migrate though rivers or streams and reach reservoirs? Might the dye poison wildlife? If it makes the water look black it is absorbing light and that would make the upper layers of the water warmer and the lower levels colder than usual, and that could affect aquatic plants and animals.

Did the police concerned know the answers to those questions? Did they even ask the questions?