Visitors warned of blue-green algae at Bosherston Lakes

Natural Resources Wales (NRW) officers have identified blue-green algae at Bosherston Lakes in Pembrokeshire.

Pembrokeshire’s Environment Team has notified the landowners National Trust and warning signs have been installed at the affected central lake advising people not to have contact with the algae or the water. Pembrokeshire County Council has also been informed.

Blue-green algae naturally occurs in inland waters, estuaries and the sea. Blooms can form when their numbers become excessive. There are currently no blooms, but floating mats and rafts of algae have been detected.

It adds oxygen to water during the day but consumes it at night. This can lead to dangerously low oxygen levels which can suffocate fish and other creatures.

Bloom and scum-forming blue-green algae can produce toxins. These toxins can be very dangerous to animals. In humans, they can cause rashes after skin contact and illnesses if swallowed. 

Paul Culyer, Senior Land Management Officer, of NRW, said:

“Our Environment Team in Pembrokeshire has visited and tested the lakes, and found blue-green algae to be present in the central lake.
“There are no blooms at present, but current weather and site conditions are ideal for blooms to occur.
“Not all blue-green algae blooms and scums are toxic, but you can’t tell just by looking at them, so it’s best to assume they are and follow advice to avoid contact with it and the water.” 

You should call NRW to report incidents of blue green algal blooms or scums on our incident hotline: 0300 065 3000 (24 hours).