The public is being warned to avoid swimming in Tukituki River immediately downstream of Waipukurau.
A power outage and system failure at the wastewater treatment plant at Mt Herbert Rd, Waipukurau on Monday afternoon caused a raw sewage leak which overflowed into the Pah Flat drain, and into the Tukituki River.
This is being investigated and samples of the discharge have been taken for analysis.
Hawke's Bay Regional and Central Hawke's Bay District Councils are advising the public to avoid contact with areas immediately downstream of the Tukituki river for the next few days.