Horizons Regional Council has made only four prosecutions in the past three years.

Horizons Regional Council has made just four prosecutions in the past three years.

Horizons strategy and regulation group manager Dr Nic Peet said that like many other councils around the country, they had seen significant improvements in compliance rates.

Peet said the council had "a number of regulatory instruments" at its disposal and used these tools as appropriate to the situation. These include advice letters, followed by formal warnings, abatement notices, infringement notices, enforcement order or interim enforcement order and, if needed, prosecution.

In the past three years only four cases reached prosecution.

These included:

2015/16 – One prosecution before the courts . Horizons was unable to provide further comment.

2013/14 – Prosecution against Ruapehu Alpine Lifts for a diesel spill.

2012/13 – Prosecution against AFFCO for an industrial wastewater discharge, and one prosecution against a farmer for dairy effluent discharge.

Peet said serious offending resulting in prosecution was relatively rare.

"Prosecution is generally used as a last resort and considered where offending has serious adverse effects and/or is of an ongoing nature."

Peet said that the prosecution of Ruapehu Alpine Lifts, which concluded in 2014, had a significant fine.

Catalyst Group planning consultant Greg Carlyon accepted the council had other means before it got to prosecutions, but did think the number over the past three years was low.

He worked for Horizons from 2004-2011 and said during that time there were 29 prosecution cases.

Carlyon said when he started there was a 60 per cent significant non compliance rate, and when he left that was about 60 per cent compliance.

"It has improved, there is no question about it."

Carlyon said it was "fair enough" that the council chose to talk to people instead of take action, but noted "you still have to hold people accountable".

He said prosecutions were the only way to get accountability.

"People do make mistakes, but you sort them out, acknowledge them and move on."

Horizons chief executive Michael McCartney said they were confident in that their regulatory process would stand up to independent assessment and they benchmarked themselves against other councils.

"It is positive to have prosecution rates remain consistently low for the last three years and believe this is a result of a greater recognition by consent holders of the need to comply."

Peet said Horizons had internal procedures in place to determine which enforcement tools were appropriate to use in a given situation. The factors used to make this assessment were: Actual and potential environmental effects; the conduct of those involved in the offending; the deterrence required; and public interest.

The Manawatu-Whanganui council has about 4800 active resource consents which traverse activities from farms, district wastewater treatment plants, and industrial businesses across the region.

Peet said action could be taken for breaches of consent, but was not that common. More often were illegal activities or breaches of regional plan.