A sewage leak is threatening one of Golden Bay's most popular beaches.
Up to 700 swimmers a day used Pohara Beach during the summer holidays.
Tasman District Council spokesperson, Chris Choat said the sewage was found at the Pohara Stream behind the Penguin Cafe.
He said although the beach was still open the council has put out signs advising against swimming.
Tasman mayor Richard Kempthorne said staff were going door-to-door to try and find the cause.
"There has been some effluent and I know that council staff are trying to track down where it comes from.
"We can't just have that continuing, we will be looking at locating the source and dealing with the source."