A Northland farming leader says Fonterra and councils should be showing no tolerance for any farmer who blatantly breaches clean stream rules.
Farmers of New Zealand operations director Bill Guest was commenting on a Whangarei man's efforts to stop a dairy farmer from polluting the Wairua River.
Milan Ruka, who leads a river patrol group, says he has filed three reports with Northland Regional Council showing a large dairy herd grazing the banks, drinking from the river, and fouling the water.
He says the farmer has no water troughs in his paddocks and has ignored a council request to put up a fence.
Mr Guest says that sort of behaviour lets down most farmers who try to comply with the dairy industry Clean Streams Accord and the farmer should be punished.
"I think if a dairy farmer is in breach of the accord, Fonterra should take the appropriate action, which includes ceasing the supply, because at the end of the day one case lets down the cases of 10,000 other dairy farmers."
Mr Guest said the regional council should prosecute farmers who are not applying with the accord.
He said it costs little to put up a single strand electric fence to keep stock out of waterways.