Local Government New Zealand says a suggestion that there be government appointees on local bodies to tackle water pollution would require a major law change, and much less drastic action would be preferable.
The comments follow a report from the office of the Auditor-General that says regional councils are not doing enough to prevent the degradation of fresh water by dairy farms, and councillors are getting in the way of prosecutions taking place.
Environment Minister Nick Smith says the Government will consider a suggestion by the Land and Water Forum to appoint goverment representatives.
But the principal adviser at Local Government New Zealand, Michael Reid, said that would alter the constitutional nature of regional councils in particular and require changing the Local Government Act.
"It confuses the constitutional separation between central and local government, so it would be a really big, precedent-setting measure."
Mr Reid said it would be preferable for firmer guidelines to be introduced for councils on how they deal with infringements.
Dr Smith said that although the amount non-compliant dairy farmers can be charged has doubled and the number of prosecutions has trebled in the past three years, the Auditor-General's criticisms are accurate.
He told Morning Report the bigger problem lies in rural areas, but there are problems in urban areas too, such as the Palmerston North City Council which has failed to comply with its resource consent for its sewage scheme.
"I'm receiving advice as to whether we should do a formal inquiry into that specific example, and the reason is to try and give clearer guidance, because regional councils are not getting this business about when to prosecute correct."
A Palmerston North City Council wastewater plant has repeatedly exceeded the amount of pollutants it is allowed to discharge into the Manawatu River since it opened in 2003.
The report looked at four councils: Waikato, Taranaki, Horizons in the Manawatu Whanganui area, and Southland.
It concluded that Waikato and Southland were not doing enough to prevent damage by dairy farms.
The report gave Taranaki Regional Council the best write-up, saying overall it is maintaining and, in places, improving water quality.
The Manawatu regional council was keeping up water quality standards in the Rangitikei and Whanganui River catchments, but not for the Manawatu River.
Assistant Auditor-General Bruce Robertson says a real area of concern at all four councils was the involvement of councillors in deciding whether to prosecute farmers.
He says these matters should only ever be dealt with by independent council staff.
The executive director of environmental group Ecologic, Guy Salmon, was one of those who peer reviewed the report and says the main reason councils are failing to keep the nation's lakes and rivers clean is that most are run by farmers.
He says regional councils are also failing to even introduce policies to keep lakes and rivers clean.
Waikato regional council chair, dairy farmer Peter Buckley, disagrees that councils are not doing enough and says his council has processes to deal with the issue.
He says councillors like to have a say on whether prosecutions proceed and make certain that the process is correct, because it's their neck on the line if a bad decision is made by staff.
Mr Buckley says his council has prosecuted other councils in its jurisdiction and has also cut non-compliance to around 10%.
The Auditor-General's report does, however, say the Waikato council needs to devote more resources to monitoring, noting that at present it is visiting just a quarter of the region's farms.
Southland Regional Council chair Ali Timms would like to see the instant fine the council is permitted to impose on dirty dairying practices increased from $1000 to $5000.
Ms Timms told Morning Report that the instant fine usually shocks farmers into remedying the problem but an increased penalty would be more effective.
Government inspectors suggested
An OECD expert on water pollution and farm runoff says the New Zealand Government could look at using farm inspectors and reducing stocking densities to control water pollution.
A policy analyst from the OECD's trade and agriculture directorate, Kevin Parris, told Nine to Noon that overall water quality in New Zealand is high but intervention is needed to keep it that way.
Stocking limits could be imposed in certain catchment areas where even the best practices can not stop pollution.
Alternatively, he says, society may decide to "give up" on a particular river or lake and let it be polluted because there's an economic benefit.