The quality of water at one of Northern Ireland's most popular seaside resorts is among the worst in Europe, environmentalists have warned.
Overflowing sewer pipes and increased discharge from farm waste have been blamed for bacterial pollution at Newcastle beach in Co Down.
Property developers who bypass the water treatment network in an attempt to cut costs have also had a detrimental impact, the Marine Conservation Society (MCS) said.
"Livestock waste from the fields behind Newcastle, a lack of capacity in Newcastle and mis-connected plumbing all act together to drag down the water quality," said Robert Keirle, pollution programme manager with the MCS.
According to the Good Beach Guide, Newcastle was the only beach in Northern Ireland that failed to meet the European standards for bathing.
The town's antiquated sewerage network has failed to cope with the population swell during the summer months and the high volume of rainfall and flooding last year has added to the problems.
"There are still a lot of combined sewage overflows that need attention, and farming is an important part of Northern Ireland's economy so although the problems with discharges from NI Water's sewage treatment works have been largely addressed, this has now exposed the significant impact diffuse pollution from agriculture and urban areas is having on Northern Ireland's coastal waters," added Mr Keirle.
Fifteen out of 23 Northern Ireland bathing beaches tested last summer had excellent water quality, with investment in the sewer system reducing pollution. Major efforts are now being made to tackle the problem in Newcastle, said the MSC.
"It has been bad for years. This is not a new phenomenon but, Northern Ireland Water has had to prioritise where it spends its money. They are doing their best. Their investment programme has seen them install bigger sewers where needed and improving waste water treatment works," Mr Keirle said.