WATER bosses are counting the cost of damage to Bolton's countryside after flash floods left a trail of devastation.

Rangers say boulders the size of cars left 15ft craters in the ground near Entwistle Resevoir. And many bridges linking popular walkways were ripped up by the force of the water.

Heavy rains last Thursday night brought water cascading down Cadshaw Valley and into the resevoir.

The torrential downpour caused a stream to burst its banks and spark a mini-landslide.

Trees were uprooted and footpaths across the West Pennine moors, near Rivington, were wiped out.

Officials from water giant United Utilities say the damage amounts to £100,000.

And they are warning trekkers to stay away from some walking trails, as these are still unsafe.

Signs have been erected to alert walkers about potential dangers, but some people are ignoring the warnings.

It could be 12 months until United Utilities builds new flood defences and the trails reopen.

Alternative walking trails are still open around Jumbles Resevoir and Wayoh Resevoir.

A spokesman for United Utilities said: "I've never seen anything quite like it. It just shows how devastating nature can be.

"We should be thankful that the downpour happened late at night when there were no walkers around. Otherwise the consequences could have been a lot more serious."

He warned walkers: "Please stay away from the cordoned off areas, or you'll be putting yourself in danger."

Bolton was hit by flash floods last Friday when rain poured off the moors into Egerton and Belmont.