Toxic algae found in Hampstead Heath’s ponds

�A poisonous algae that causes vomiting, diarrhoea and skin rashes in humans and can be fatal to dogs has been detected in Hampstead Heath’s men’s swimming pond.

Warning signs have been put up all around the men’s pond and the model boating pond telling swimmers – particularly those with children and dogs – to avoid water near the algal ‘scum’.

Tests by the Corporation of London revealed the presence of high levels of blue-green algae in the men’s and boating ponds. The environment agency has been called in to carry out its own emergency tests, the results of which will not be known until next week.

Swimmers who flout the advice could suffer skin rashes, eye irritation, vomiting, diarrhoea and fever if they swallow contaminated water.

Dog owners will also have to keep a tight hold of their leads as the algae can kill dogs and other animals if ingested.

Five years ago three swans were found dead in Edinburgh after a blue-green algal bloom in a city pond.

The Serpentine in Hyde Park – where many keen Hampstead outdoor swimmers also take a dip – has the same problem with blue-green algae and fears are growing that it may return next year and put the lake’s Olympic triathlon events in jeopardy. But despite the warnings, Hampstead’s hardy swimmers seem undeterred.

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Al Alvarez has been swimming in the ponds for over 70 years and won’t let algae stop him.

He said: “I’ve been swimming here since I was 11 and I’m 82. Apparently, algae are just like any other flower – it blooms, then it dies.”

Other swimmers will remain on their guard but will not be over cautious and let it ruin their summer fun.

Johnny Amodi said: “It’s not dangerous until it turns blue. That has not happened yet. If it went blue I would stop. That is the general consensus amongst the older guys. They have not closed the pond and I’m sure they would if it turned blue.”A spokesman for the Corporation of London, which manages the Heath, said: “We took our own samples which indicated the presence of blue-green algae in the men’s bathing pond.

“We have put notices up warning swimmers of the possible dangers associated with swimming in water with detectable levels of blue-green algae.

“It is a sensible precaution for swimmers, children and animals to avoid contact with any scum and the water close to it, but the pond is still open.”