Around 100 trolleys were pulled from part of the river Rhondda

Currently around 100,000 trolleys, costing �80 each, are stolen from supermarkets across the UK every year.

But along with the concern of the losses pushing up food prices, trolleys clogging up waterways has also rasied concerns over flooding and pollution.

One of the examples used as part of the scheme is the river Rhondda in the Rhondda valley.

Although the water is cleaner than it has been for over a century, it is suffering from pollution of a different kind - shopping trolleys.

Culture change

More than 100 were found by volunteers along one short stretch of the river at Porth.

"People don't seem to realise that by taking a trolley out of the supermarket and leaving it on the side of the road, it can end up in the river," said Louise Tambini of the Keep Wales Tidy campaign.

"I don't think that has come across very well in the past."

Supermarkets have begun a poster campaign

Supermarket giant Tesco already has an anti-theft device - an infra red device which immobilises the trolley once pushed a certain distance from the store.

But even that high-tech system cannot stop the most determined thieves according to Keep Wales Tidy, who believes only a culture change will stop the most the thefts.

Currently around 100,000 trolleys are stolen from supermarkets across the UK every year.

Once the trolleys have been recovered from the river they will then be recycled by Symonds Hydroclean - a Welsh firm that specialises in recycling abandoned shopping trolleys.