A suspected sewage leak has closed Wellington's Owhiro Bay beach on the southern coast to the public.
Wellington City Council has put up "beach closed" signs and was urging people to stay clear of the water in the area until further notice.
Routine water-quality monitoring earlier this weekfound the presence of enterococci -- an indicator of microbiological pollution, including sewage -- in Owhiro Bay was at a level likely to cause a health hazard.
Council infrastructure planning manager Maria Archer said daily sampling had since found the levels had remained high.
The beach was closed following consultation with Regional Public Health staff.
Ms Archer said people were "combing the area" for the source of the contamination.
"As soon as we find it we can stop it," she said.
The source was not obvious and did not appear to be coming from the Owhiro Stream, "so there may be a broken sewer main in the area".
She hoped the beach could be reopened within the next few days.
Medical Officer of Health Stephen Palmer said the presence of enterococci in the water indicated it was unsuitable for swimming or recreational contact.
Health problems that could be associated with the ingestion of contaminated water included diarrhoea, stomach cramps and vomiting.
Cuts and skin lesions could also become infected, Dr Palmer said.
