Easter holidaymakers at Raglan are being urged not to swim in the harbour after raw sewage spewed from a broken pipe.
Waikato District Council said untreated wastewater had entered the harbour after the main inlet pipe to the Marine Parade pump station collapsed about 8pm yesterday.
"Waikato District Council staff and contractors were on site quickly and stayed on site through the night to as much as possible limit any further wastewater entering the harbour," council service delivery general manager Tim Harty said.
"A temporary solution to pump wastewater is now in place. This is being run manually while a repair is undertaken today."
Mr Harty said the council had put up signs in the area advising the public not to swim or collect shellfish until further notice.
The council would investigate the cause of the pipe collapse and would keep the regional council informed.