Blue-green algae warning at Snowdonia's Llyn Tegid

Llyn Tegid in Bala is Wales’ largest natural lake and is a popular place for water sports 

Tourists are being warned to take extra care when visiting a popular North Wales lake after harmful blue-green algae was found in the water.

Snowdonia National Park said the blue-green algae had been found in parts of Llyn Tegid in Bala.

It urged people to be careful around the lake and avoid direct contact with the algae.

The lake is popular with water sports enthusiasts

“Blue-green algal bloom is a natural phenomenon that has occurred in Llyn Tegid for many years," the National Park Authority said in a statement.

"It mostly appears during periods of fine, hot weather and can be easily identified from the bright green coloured scum floating near the shorelines."

Visitors are being asked to familiarise themselves with the safety notices on the foreshore, and not to enter the water when algal bloom is present.

If the water is not crystal clear, visitors should err on the side of caution and keep out of the water, the park authority said.

The algae produce toxins which can cause skin rashes, nausea, eye irritation, vomiting, fever, diarrhoea and muscular or joint pain if swallowed.

The park authority also warned pet owners to contact their vet immediately if their dog appears unwell and had been in contact with blue-green algae.