The pond before it was closed due to polluted water [Geograph]

THE Ladies Pond on Hampstead Heath has been shut again this week after water tests found it too polluted for bathers to swim in.

It follows a closure last month after Heath staff discovered traces of sewage in the spring-fed pond.

Swimmers say they fear a reduction in the number of water quality tests carried out over the summer due to the Covid-19 pandemic raises questions about how safe the water, which usually enjoys an Environment Agency rating of excellent, has been in recent months.

Daily testing has now returned to the Ladies Pond.

In September, the pond was shut for more than a week after a Thames Water sewer pipe, which runs from Kenwood House towards Millfield Lane, fractured. 

Engineers say tree roots caused damage. They say they used a tanker to pump out waste water before repairing the pipe. 

But Thames Water say they do not believe the pipe break has caused the most recent issue.

“There’s no indication that any waste water got in to the pond,” the company said. “We carried out tests which showed no impact on water quality.”

It added the latest closure could instead be caused by heavy rain falling over the weekend and run-off from surrounding hills joining the water courses that flow into the ponds.

A City spokesman said: “Since the closure of the following last month, we have increased our water quality checks which are currently being carried out daily.

“The bathing pond reopened on September 26 when tests confirmed the water had attained the highest level of quality for swimming, and this has continued to be the case in subsequent tests. However, the test results we received on Sunday revealed the water was not of a satisfactory quality.

“We believe this is the result of heavy rain on Friday and over the weekend washing impurities into the water, and is not linked to last month’s Thames Water incident.”

The City have introduced extra hours at the Lido for women only sessions while the pond remains closed.

The spokesman added: “We thank swimmers for their understanding and will reopen the Ladies’ Pond as soon as the water quality reaches a satisfactory level again.”

Swimmers have warned in recent years that proposed developments on the fringes of the Heath threaten the delicate balance of water courses that feed the ponds, and fear extra rainfall could mean closures become more frequent.

Kenwood Ladies Pond Association vice chair Mary Powell said: “It is very disappointing that the Ladies’ Pond has been closed at short notice for the second time in three weeks due to water contamination, in particular the E-Coli levels. ”

“The latest instance appears to be connected indirectly to the first incident, via wash off of contaminated soil during recent heavy rain.

“After the first incident we discovered how infrequently water testing had been happening during the summer despite the wider context of a public health emergency and the inflated new charges to swim.

“The KLPA continues to press the City of London and Thames Water for clear answers as to what happened and why it took so long to respond in the first place.  Supervised open water swimming venues are supposed to benefit from regular water testing but it looks like we might as well be swimming in unregulated waterways.

The City of London is failing in its duty of care to swimmers.  We urge any Heath pond swimmers who have suffered ill effects recently to notify the City.”