As people gather in Northland to celebrate Waitangi Day on Sunday, a health warning has been issued over polluted waterways.
At least 35,000 people are expected to attend commemorations marking the 171st anniversary of the signing of the Treaty of Waitangi during the weekend.
Heavy rain has caused stormwater, sewage and farm effluent to overflow across the region, the Northland District Health Board says.
Medical officer of health Clair Mills says visitors to Waitangi and the region should avoid eating seafood until further notice and not swim unless the water looks clear and uncontaminated.
Ms Mills says while no one can control the weather, better sewage management and farming practises could have avoided the current predicament.
Green Party co-leader Russel Norman agrees, and has described the situation as embarrassing and unacceptable.