Figures from two regional councils show a further improvement in compliance by dairy farmers with effluent rules.
Manawatu-Whanganui Regional Council says more than 90% of the 922 farms it inspected over the past season complied with effluent discharge conditions.
The council says that's 10% higher than the previous season and is one of the best results its had in the past eight years.
Only 7% of the dairy farms checked had significant non-compliance issues.
Otago Regional Council says 94% of the 400 dairy farms it inspected in the past season complied with its rules.
It has laid 10 prosecutions against farmers for discharge breaches.
That's well below the more than 40 prosecutions laid in in the 2008/09 seasons, which the council says made dairy farmers more aware of effluent issues. Some have substantially upgraded their systems as a result.