A health warning is in place following a significant discharge of effluent into the Makino Stream in Feilding.
The discharge happened around 7pm on Friday, Dr Nic Peet, Horizons Regional Council strategy and regulation group manager, said.
"Three Horizons pollution response officers identified a significant discharge of animal effluent into the Makino Stream near Rata St," he said.
"The source was identified and ordered to stop immediately. Unfortunately, effluent had already entered the stormwater system and into the Makino Stream.
"We have spoken to Public Health and we both have concerns for anyone using the Makino Stream or the Oroua River downstream of Rata St.