Bay of Plenty Regional Council says the message to keep animal effluent out of waterways, continues to fall on deaf years among some dairy farmers.
The council says three cases of serious non-compliance, heard in the Tauranga District Court this week and resulting in fines of about $50,000, bring the total prosecutions in the past year to eight.
There were six prosecutions the previous year.
During the sentencing of one farmer, Judge Jeff Smith questioned the reliability of irrigation machines for spreading dairy effluent onto farm pastures.
Council spokesperson Eddie Grogan says the problems seem to be largely with failing irrigator systems or the pipe work that's attached to them.
He says that indicates poor design or poor management of the system and people are not doing the necessary maintenance or inspection work to ensure their systems aren't going to break down.
Mr Grogen says Fonterra, Dairy New Zealand, Federated Farmers and the regional councils around the country are putting a lot of effort into trying to get 100% compliance every day of the year.
But he says despite the effort and the education material there is still a small level of serious non-compliance each year.
Mr Grogan says the council has set up a dairy working group in response to that, and he hopes it will encourage farmers to better manage their effluent.
Meanwhile, there's been another hefty fine imposed in Waikato for effluent discharge offences.
An Otorohanga dairy farm owner and herd manager were fined more than $50,000 for allowing large volumes of effluent to pond on pasture, which a Hamilton district court judge said could have contaminated groundwater.