Rāhui in place after wastewater discharged into Canterbury harbour

A rāhui is in place around Lyttelton Harbour in Canterbury after untreated sewage was discharged into its waters on Friday.

Lyttelton Harbour Sewage Discharge Prompts Health Warning and Rāhui

A health warning was issued by Health New Zealand covering several areas, including Te Waipapa/Diamond Harbour, Purau Bay, Kaioruru/Church Bay, and Te Wharau/Charteris Bay. A seven-day rāhui on taking seafood within Whakaraupō/Lyttelton Harbour was put in place by Te Hapū o Ngāti Wheke (Rāpaki), through the Rāpaki Tangata Tiaki, as of 5pm yesterday.

Authorities advise avoiding eating shellfish, fish, and other kaimoana from the harbour. Dr. Imogen Evans, a public health medicine specialist for the National Public Health Service, stated that the water quality in Diamond Harbour is “not considered suitable for recreational uses, including swimming, because of the risk to health from the bacteria and other pathogens.”

Contaminated water may contain disease-causing micro-organisms such as viruses, bacteria, and protozoa. The hapū are contacting anyone who received permits over the last 24 hours, and no further permits will be issued during the seven-day rāhui, and “possibly beyond,” according to Health NZ.

‘Visible Contamination Plume’ Observed

Environment Canterbury compliance manager Jennifer Rochford said the amount of sewage discharged is not yet known. A visible contamination plume was observed in the harbour earlier, and while it has reduced, it continues to move toward the harbour heads with the outgoing tide.

Environment Canterbury will work closely with the council to understand what went wrong and how to prevent a repeat incident once the situation is stabilized. Christchurch City Council has closed the affected pump station.

The discharge follows a recent wastewater incident in Wellington, where a “catastrophic failure” at the Moa Point Wastewater Treatment Plant sent raw sewage into the city’s southern coastline.