Effluent compliance rates for Otago dairy farms last season were "pretty good" overall, Otago Regional Council senior environmental officer Richard Lord says.
Mr Lord was addressing a pre-calving field day at Jason and Sheree Hayman's property at Kia Ora, inland from Oamaru.
The event covered effective nutrient and effluent management, with input from the ORC, Fonterra, Dairy NZ, Ravensdown and the North Otago Irrigation Company.
Inspectors visited 391 dairy farms throughout Otago and 91% were fully compliant - slightly down on 94% last year. Just under 2% were non-compliant major and 7% were non-compliant minor.
Those who were non-compliant were dealt with in a range of ways, from a formal warning to an infringement notice, and some were prosecuted, Mr Lord said.
North Otago Irrigation Company environmental co-ordinator Jodi Leckie said the company sought full compliance with ORC rules.
Effluent compliance within NOIC shareholders had "sky-rocketed" this season, she said.
If a farmer failed their NOIC audit and did not make any attempt to work towards resolving environmental issues, then the company would turn the water off. However, it tried to work with farmers to avoid that situation.
The ORC was committed to ensuring farmers were well set up to manage their dairy waste and reap the nutrient benefits from good effluent application, land resources officer Dylan Robertson said.
The council's rural water quality strategy highlighted that run-off from farmland could carry excess nutrients, such as nitrogen, phosphorus, bacteria and sediment.
The nutrients could contaminate waterways, promoting algal growth and creating health concerns if swallowed. Bacteria could create similar health concerns, while sediment discoloured water, clogged fish gills and buried river bottom habitats.
Contaminated runoff was a challenging issue for everyone in land management and the ORC had been encouraging farmers to work together to improve water quality as part of a re-appraisal of the Otago Water Plan.