From Hart Countryside Services:
“Blue Green Algae occurs naturally but blooms like those at Fleet Pond occur when numbers become excessive. It is a temporary bloom and occurs during prolonged dry periods followed by rain. The rain flows through the catchment washing nutrients into the streams and ditches which then enter the pond in a process called eutrophication.
People should ensure that they do not enter the pond or make contact with the water. Toxins in the algae can cause skin rashes, eye irritation, fever, diarrhoea and fever in people who have swallowed or swam through algal scum. The toxins in the algae are also harmful to animals so pet owners should keep their animals away from the pond.
If people have made contact with the water they should not panic as the symptoms described above do not occur in every case. People are advised to wash their skin down after contact with the affected water but if symptoms persist people should visit a doctor. If their pets become ill after drinking affected water they should seek veterinary advice.”