Forest and Bird has hit out at authorities over what it calls an "environmental crime wave" in Canterbury, where irrigators have illegally taken vast quantities of water without being prosecuted.
The environmental group has revealed data showing hundreds of instances of irrigators repeatedly breaching water consent conditions and being caught without functioning water meters -- but only being given warnings by Environment Canterbury (ECan).
The authority has responded by saying it takes the issue seriously and is leading a new compliance programme in the region.
Information obtained by Forest and Bird showed one serious repeat offender was noted by ECan as "continuously overusing" water "throughout the season and for the last three seasons" but only received an abatement notice.
Another irrigator was found to have illegally uplifted 31 million litres of water from the Manuka Creek over 42 separate days -- 40 of which were during low-flow restrictions, when rivers were already at their most parched.
The person also received an abatement notice.
In another case, a public complaint about Wairepo Creek running dry led to a site inspection and an irrigator was noted as having multiple serious non-compliance issues including exceeding water flow, and using water for the wrong purposes.
Again, the consent holder taking the water received an abatement notice.
"Let's be clear -- these are serious environmental crimes that are punishable by fines and prison sentences under the Resource Management Act, yet ECan seems unwilling to do much more than issue abatement notices, which it then fails to enforce," said Forest and Bird's senior legal counsel, Peter Anderson.
"Several of these instances deal with repeat offenders; one has been noted as having illegally taken water for at least the last three seasons, and ECan still had not prosecuted them.
"Elsewhere in New Zealand abatement notices are taken very seriously. However, in Canterbury irrigators seem to be able to be ignore them with impunity."
In other instances of offending, dozens of irrigators were caught without functioning water meters.
"Without a functioning meter, irrigators are free to take as much water from the local rivers and aquifers as they like without anyone knowing," Mr Anderson said.
"It is a standard condition of consents that the irrigator must, before taking any water, install a water meter, and have a tamper-proof electronic recording device.
"There is simply no excuse for taking the water for months or even years before installing a water meter."
Among the instances of people failing to properly use or install water meters was one case where a consent holder's water take was so large, Forest and Bird said, that the monitoring officer wasn't sure if the water meter was working properly or not.
ECan wrote to the person -- whose water take was recorded at 186 million litres over a year -- telling them that the potential of a third irrigation season without accurate water data was "unacceptable" and issued them an abatement notice.
Mr Anderson noted how ECan commissioner David Caygill had recently questioned whether anyone took ECan notices seriously.
"The data demonstrates that many consent-holders do not, because ECan has given them next to no reason to do so," he said.
"Commissioner Caygill's recent indication that ECan should treat consent breaches more seriously is welcome, but until ECan starts taking strong enforcement action we will continue to see irrigators ripping off their neighbours, their community, and the wildlife that depends on Canterbury's rivers and waterways."
The Green Party today also raised serious concerns around ECan's oversight, referring to new Ministry for the Environment data that showed it monitored 3200 of 20,000 consents in the 2014/15 season.
Of the consents monitored, more than half were found to not be complying with their conditions, the party said.
"Canterbury is fast becoming a Wild West, with too many environmentally risky activities going unchecked by the council," said the party's environment spokesperson, Eugenie Sage.
"With so many environmentally risky activities going unmonitored, the illegal taking of water in Canterbury could well be worse than what is currently reported."
ECan has responded to the criticisms saying it takes non-compliance "very seriously", particularly around water use.
Richard Purdon, ECan's principal resource management adviser, said the evidence required for pursuing a prosecution was very high.
While several investigations have taken place over the past two seasons for breaching consent limits, none reached the evidential threshold for prosecution, he said.
"However, abatement notices and fines by way of infringement notices have been issued."
The authority was responsible for monitoring three times more water takes than any other region and had been working with water consent holders and the irrigation industry around national water metering rules that took effect in 2012.
"Given the scale of the task in Canterbury this has been a huge job -- it is now largely in place and our focus is on dealing with the small number of people who have not complied, as well as encouraging water use and nutrient efficiency."
Last month, ECan began a programme with consent holders to ensure all complied with the rules, and all of those who have yet to install meters -- around 9 per cent or 500 consent holders -- had been contacted and warned they face enforcement action if they failed to take urgent action, he said.
"What we have found is that once contacted, many people took action within 10 days or provided evidence they will comply within a set time."
ECan had begun issuing abatement notices to those who had not responded and this would lead to enforcement action, he said.
"By July we want all water-take consents to have an appropriate water meter, and for all water consent holders to provide information to show they comply with their consent conditions."