The alarm was raised this week by a member of the Alexandra Park Community Group, after signs of the algae were spotted in the body of water between Harmers Pond and Shornden reservoir.
The Environment Agency has been informed. If Blue Green Algae is confirmed, the bloom could be toxic. People and pets should avoid any contact with the water.
The algae takes the form of a pea green scum on the water surface, which can also look like paint or jelly. Some species of blue-green algae produce harmful toxins which take effect when eaten, inhaled or skin contact is made. Contact with affected water can cause skin irritation, nausea, vomiting, fever, mild respiratory effects and hayfever-like symptoms and, more rarely more serious illness.
Symptoms of acute cyanobacterial poisoning may develop within minutes, hours, or days, but most commonly manifest within 24 hours of exposure. Skin rashes may take up to two days to appear.
Not all Blue Green Algae blooms are toxic but professional advice is to assume that they are.
Blue Green Algae are not algae but a type of bacteria, called cyanobacteria, that are present in our lakes and rivers. It is not down to pollution, but a natural occurrence in UK waters and the algae will died back in the winter.