Bay of Plenty Regional Council says dairy farmers have lifted their performance in complying with effluent discharge rules, but there's still room for improvement.
The council said 74% of the 297 farms visited during the dairy season fully complied with their consent conditions. That's an improvement on last season's 67%.
Significant breaches, where overflowing effluent threatened waterways, dropped from 14% to 11%.
The biggest issues were with adequate effluent storage, irrigation system maintenance and stormwater diversions.
Pollution prevention manager Nick Zaman said the number of significant breaches was the lowest in four seasons.
He said no farms are being prosecuted this season as a result of compliance inspections, but some high profile dairy effluent court cases over the past two years may have been a deterrent.
Last year the council prosecuted eight dairy farmers. They were fined a total of more than $320,000, or an average of $46,000.