YOUNGSTERS are dicing with death swimming in deep quarries and reservoirs to cool off during the heatwave, authorities have warned.

Bosses at Jamestone Quarry, off Grane Road, Haslingden, said parents were even dropping off children so they could go for a swim in the cold water.

Up to 200 teenagers and young adults have been seen sunbathing and diving off rock faces into the 10-metre deep water, known as the Blue Lagoon.

And near Burnley, groups of up to 30 people a day have been gathering at Clowbridge Reservoir to swim in the water.

But when members of the local sailing club approached to warn them about the dangers, they were ignored.

Doug Forbes, commodore of Rossendale Valley Sailing Club, is worried there could be a fatality.

He said: “It’s a very concerning issue. I fear that one day I’m going to get a phone call telling me that a body needs pulling from the reservoir.

“On Saturday there were around 30 people were swimming there. I don’t think they realise that once you get 18 inches below the surface, the water temperature is as cold as it is in November.

“United Utilities have put up ‘no swimming’ signs which also warn that there is dangerous green algae in the water but they are just ignored.”

Quarry bosses said they had stepped up security to prevent an ‘inevitable tragedy’.

But they said people were flouting warning signs by climbing over security fences and ignoring guards’ threats to call the police.

A spokesman for site managers Aggregate Industries said: “We are doing absolutely everything we can to keep people from coming in and hurting themselves, or worse.

“Parents have been dropping their children off at Jamestone so they can go and swim.

“Some people don’t seem to realise just how dangerous it is.

“The temperature of the water can be icy cold, extremely deep, have unexpected currents, pumps or other objects hidden beneath the water.

“The dramatic impact that cold water can have can leave even experienced swimmers suddenly finding themselves in difficulty.

“It’s illegal to trespass, but the very real danger of somebody dying after jumping in our quarry that we’re really concerned about.”

One resident, who lives yards from the quarry entrance, said: “The lane and car park to the quarry was blocked by cars last weekend. There must’ve been 40 cars parked on our little lane.

“I don’t know if they realise how deep it is in the quarry.

“Some brought a portable generator and an electric barbecue.

“They’ve been leaving smashed glass bottles and beer cans lying around as well.

“The rock climbers which use the place came and put the rubbish in a bin which was left by the people who went swimming.”

Authorities listed icy cold water, unstable rock surfaces, hidden scrap metal or machinery and quicksand as potentially fatal reasons to stay away from the pools.

John Taylor, from Lancashire Fire and Rescue Service, said: “It is very unsafe and we don’t say that just to take a nanny state stance. Going from experience we have been put in positions where we have to attempt to rescue people from canals. But often we only succeed in recovering a body, because the effects of cold water can be so sudden a rescue is not possible.

“There is a very real risk of injury and death.”

Sgt Mark Taylor, of Rossendale Police, said: “We know people like to have fun in the water when it’s hot outside but you should use common sense and not put yourself at risk.

“We pull stolen cars out of reservoirs and quarries and you could be very nasty if you dived into one of those.

“Water in them can be stagnant and give you stomach trouble. Going messing around in quarries isn’t a good idea.”