Prosecutions for environmental pollution in New Zealand have more than halved over the past five years.

Ministry of Justice figures show there were 234 prosecutions last financial year, with 38 per cent resulting in convictions. Five years earlier, there were 555 prosecutions -- with convictions in 43 per cent of cases.

One leading environmental consultant believes regional councils have been accepting "donations and contributions to council environmental work" as mitigation for alleged breaches instead of pursuing prosecutions.

A Ministry for the Environment spokesperson said enforcement of the Resource Management Act was the responsibility of local authorities. Prosecution was only one of the formal enforcement options and normally a last resort. Other options included abatement notices and enforcement orders, letters and verbal warnings.


Greg Carlyon of The Catalyst Group led prosecutions for Manawatu-based Horizons Regional Council up until 2011 and said there had been very few prosecutions in the region since then.

"I would say I have no confidence at all that levels of compliance have improved. There's no data to support that."

Mr Carlyon said council claimed it was working with people rather than against them but he didn't believe its methods were working.

"The evidence for that is that water quality is still declining. We've got obvious non-compliance around the region in terms of discharges, stock in water and other things, and the message is not getting through."

He thought the regional council needed to consistently enforce its regulatory commitments and hold people accountable. Mr Carlyon said he also believed councils were doing deals with parties once enforcement proceedings began.

"Those parties are effectively mitigating their way out of the legal action by making donations and contributions to council environmental work and other things," he said.

He didn't think there was enough transparency and any such negotiations should be done in the public domain.

Mr Carlyon said he was also concerned there was too much political involvement in prosecutions. The majority of regional councils in New Zealand included councillors when determining whether enforcement action would be taken, contrary to Crown guidelines.

University of Auckland Associate Professor Kenneth Palmer said he wasn't surprised with the drop in prosecutions as he believed people were becoming better educated about their environmental responsibilities.

Farmers had proper effluent treatment measures, regional councils were making sure farms were complying with the rules and people weren't polluting the way they used to.

Enforcement around the transportation of hazardous substances was also stricter.

"So overall, better standards, better education, safer practices. So that's good news that people are getting the message and are now not trying to get away with things."

Dr Palmer said identifying offenders could be an issue in many pollution cases and there was nothing to stop parties going to council and trying to work out a compromise.

Sustainable Wairarapa convener Don Bell, previously a land management officer for the Greater Wellington Regional Council, said he'd worked with farmers on intensively managed dairy farms in the Wairarapa Valley.

He said many farmers were good custodians of their land. They tended to work to the rules and it was only a small proportion who either consciously or accidentally broke them.

Farmers were more inclined to correct their ways if approached in an unofficial way, Mr Bell said

Antagonism and angst could result when the regional council was forced to act in an official capacity, and that was almost counter productive.

"You'll always get a hardy few, that, no matter what you do, won't mend their ways. And I'm quite happy to see those hardy few prosecuted."

Bay of Plenty Regional Council pollution prevention manager Nick Zaman said a prosecution was only necessary in the most serious of breaches.

Prosecutions were time consuming and expensive, so there were advantages in not having to take a case to court.

"Enforcement action relies on a spectrum of tools to achieve compliance and, ultimately, we are after a good environmental outcome."