The controversial Heath ponds project has been slammed as a “complete fiasco” as work on the Model Boating Pond was halted because a temporary dam threatened to give way.

Ham & High: The Mark 3 Ford Cortina found during the dredging of the Model Boating Pond for the dams project on Hampstead Heath. Picture: Nigel SuttonThe Mark 3 Ford Cortina found during the dredging of the Model Boating Pond for the dams project on Hampstead Heath. Picture: Nigel Sutton (Image: � Nigel Sutton email pictures@nigelsuttonphotography.com)

Contractors BAM Nuttall have spent the last few weeks emptying the southern part of the pond with pumps while experts rescued fish and wildlife.

However they were this week forced to urgently refill it as an inspection of the temporary barrier revealed it could not cope with the resulting water pressure from the north side of the pond.

Simon Briscoe, vice president of the Highgate neighbourhood forum, said: “It is a complete fiasco and shows professional incompetence which is genuinely disturbing.

“The project has been riddled with problems with reports of leaks.

“It’s hard to believe that the professional engineers who convinced the City to do these works now can’t build a temporary dam properly. It is extremely disappointing for lovers of the Heath.”

Robert Sutherland Smith, chairman of the United Swimmers Association, who lives in Hampstead Garden Suburb, said: “It’s very unfortunate given that the cost of this whole project is so enourmous and we can assume this will now increase the costs even more, in relation to what strikes many of us as a proposterous construction in the first place.

“I am surprised that these people, who are experts in dams, couldn’t have worked out the water pressure. We were given the impression with all the computer images and models that they knew what they were doing, but it appears not.”

A statement on the City of London Corporation’s website states: “The temporary dam at the Model Boating Pond is inspected regularly to ensure its integrity.

“During an inspection on Friday it became apparent that the temporary dam needs some further work to cope with water pressure from the north side. Contractors BAM Nuttall are now temporarily re-filling the southern end of the pond before consolidating the dam and then draining the southern end again.”

A spokesman told the Ham&High: “We do not expect it to cause delay to the overall project programme. At the moment, we also do not anticipate it having any effect on the Ponds Project cost.”

Camden Council approved the scheme last January, despite a 12,465-strong petition against it and over 1,000 letters of objection.

Protesters claim the works will cause irreparable damage to the historic landscape and “vandalise” the Heath.

But councillors accepted the argument from City of London Corporation that the two years of engineering work was required by reservoir laws to prevent the dams collapsing and triggering a fatal flood if a “catastrophic” storm hits.

Work started on the £22million scheme in April, with the most significant works taking place at the Model Boating Pond.

The existing dam there is being raised by 2.5m by the building of an earth embankment on top of the current dam crest.

A new 20m wide spillway will also be built. Existing trees will be removed and a new island is to be created, connected to the Heath by a new causeway.

As reported in last week’s Ham&High, while dredging the pond contractors discovered an old car, thought to be a convertible Mark 3 Ford Cortina lying on the bed.

The car, which could have been submerged for up to 25 years, has since been removed with mystery still surrounding how it got there.

Richard Gentry, head of the City of London’s Hampstead Heath Constabulary, said: “A car has been exposed and a metallic eagle has also been found during safety works to the Model Boating Pond.

“Both objects have been reported to the Metropolitan Police as they may be of evidential value.”

A City spokesman said there was no further updates on where the car came from. The Metropolitan police also had no further information about the car.