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Frensham Pond water with blue-green algae (taken 2024 to show as reference as this year's presence is only just starting to bloom).

Date posted: 01 July 2025

Blue-green algae alert at Frensham Great Pond

Visitors to Frensham Great Pond and Common are being warned not to enter the water as the Environment Agency have confirmed the presence of  blue-green algae and are advising  'do not swim’.

Signs instructing visitors to avoid contact with the algae and warning people not to enter the water will be up on site until further notice.

Blue-green algae is a natural component of a freshwater ecosystem, but its presence is potentially harmful to humans, animals, birds and fish as well as being very harmful to dogs especially. Periods of warm weather followed by heavy rain and then further warm, still conditions cause blue-green algae to appear suddenly. There is no way of removing the algae from the water once it is established.

Waverley Borough Council and the Environment Agency recommends that people avoid the algal bloom as it can cause ill health such as dermatitis, eye irritation, rashes, blistering, abdominal pain, diarrhoea and nausea through skin, eye contact or if swallowed.

Should anyone believe that they have been affected by blue-green algae, they should seek medical advice or in the case of their pets, veterinary advice.

 Waverley Borough Council is monitoring the situation closely and will keep the public informed through its website and social media channels.

Image: blue-green algae from 2024 used as reference as blue-green algae is only starting to bloom and is not so clearly visible at present.