Waste from sewers and farm run-off is blamed as Cruden Bay loses its seaside flag award and 10 others stand on the brink. Environment editor Rob Edwards reports

Beaches across Scotland are being contaminated with sewage this summer which breaches safety limits and threatens bathers with illness and infections.

One bathing beach - Cruden Bay, near Peterhead in Aberdeenshire - has already failed to meet the legal standard for 2008. Ten other beaches have been given a "yellow card" by the Scottish Environment Protection Agency (Sepa).

These include two newly designated bathing beaches: Rosemarkie near Fortrose in the Black Isle and Seafield at Kirkcaldy in Fife. In both cases Sepa has linked the pollution to problems at nearby sewage plants, although this has been disputed by the plants' operator, Scottish Water.

The other bathing beaches to receive yellow-card warnings are: Saltcoats and Seamill, North Ayrshire; Aberdeen; Rosehearty, Aberdeenshire; Cullen, Moray; Leven, Fife; and Belhaven and Milsey Bay, both in East Lothian.

At all of these 10 beaches one sea-water sample has exceeded safety limits for faecal coliforms in the past two months. If any of them exceed the limits again before the bathing season ends in September they are likely to be declared failures for 2008 under European rules.

Although only halfway through the season, Cruden Bay has already recorded two poor samples and so has been deemed a failure for the year by Sepa. Its seaside flag award for 2008 has been withdrawn by the environmental charity, Keep Scotland Beautiful.

"We are all bitterly disappointed," said the charity's chief executive, John Summers.

"We would urge people to keep visiting the beach and to check the most recent water quality results on the information boards or online."

Sepa was also "very disappointed" about Cruden Bay's failure, but pinned the blame on wet weather before the samples were taken. As well as causing sewers to overflow, heavy rain can wash animal faeces from the land into the sea.

At Rosemarkie, Sepa has issued Scottish Water with an enforcement notice "to resolve a failure to adequately treat sewage". Sepa said that at Seafield in Kirkcaldy rain "may have given rise to the operation of sewage overflows".

Scottish Water, however, denied that its sewage works were to blame. "None of our assets that could potentially impact on the bathing water at Cruden Bay was at fault," said a spokesman.

He said that at Rosemarkie sewage effluent would flow away from the beach "in all tidal conditions". He accepted that at Seafield heavy rain "may lead to increased flows from our outfall pipes", but pointed out that animal waste from farms could also have caused the pollution.

Calum McPhail, Sepa's environmental quality manager, said: "Considering the 31% increase in the number of official bathing water sites this year, at this halfway point results are better than at the same time last year."

The Marine Conservation Society, however, was less sanguine. Calum Duncan, the society's Scottish conservation manager, said: "Overall, these provisional results from Sepa illustrate the water quality problems inherent in having very large numbers of combined sewer overflows and septic tanks lining the Scottish coastline."

He said that the bathing sites at Aberdeen had 46 combined sewer overflows carrying storm water and untreated sewage into the sea every time it flooded.

He added: "There are also significant problems with bacteria-contaminated storm pollution from farmland around the coast, particularly in the south-west.

"Billions have been invested in cleaning up Scottish coastal waters, and this has had a remarkable effect. But these latest results show that we have yet to beat the problem of periodic and unhealthy pollution at some of our bathing sites."