The public are being urged to stay out of the water at Ahuriri Estuary after 1000 litres of hydrochloric acid was spilled in Napier.
Napier City Council said fire crews were working to neutralise the acid spill at Galvanising Hawke's Bay in Napier.
Emergency services were called to Thames St, Pandora, Napier, about 4.05pm.
Fire and Emergency New Zealand said an acid spill had occurred and fire crews are working to neutralise the spill.