Pembrokeshire County Council is urging people to take care if they visit any downstream rivers flowing from a popular reservoir site.
This follows the discovery of blue-green algae at Llys y Fran recently.
The Council’s Public Protection Division, which advised people not to take part in any activities at the reservoir where immersion in water was likely, has now extended its warning to the reservoir’s downstream rivers.
Environment Agency Wales is continuing to monitor the situation and will continue to test the algae until such time that the reservoir and downstream rivers can be considered clear of it.
The blue-green algae (cyanobacteria) occurs naturally in inland waters, estuaries and seas and cannot be removed or treated.
It thrives in warm conditions so its presence is likely to come and go depending on the weather conditions. But it is not expected to clear until the weather gets noticeably colder.
The algae produce toxins, which can cause skin rashes, nausea, vomiting, stomach pains, fever and headache if swallowed. Occasionally it can cause more serious illness such as liver and brain damage.
Children are at greater risk than adults of developing problems because of their comparative lower body weight.
Llys y Fran Country Park remains open, as usual, for people to enjoy, however, in order to protect public health restrictive advice has been issued.
The advice to members of the public visiting the reservoir or downstream rivers is:
- not to swim in the water
- not to swallow the water
- to avoid contact with the algae
- not to eat fish caught in the water
- not to allow pets or livestock to come into contact with the waters as it has the potential to be fatal to animals
- to observe and abide by notices positioned at the reservoir
