Action to clean up waterways around New Zealand is not strong enough or happening quickly enough, according to a new report commissioned by Fish & Game New Zealand.
The Cawthron Institute report says already polluted lakes and rivers will only get worse under a flawed fresh-water policy, because regional councils have been given too long - up to 30 years - to set pollution limits.
The report analyses the National Policy Statement on Freshwater Management as passed by the Cabinet in May and compares it with the original policy statement, developed by a Board of Inquiry chaired by former Environment Court judge David Sheppard.
"Imagine how many more rivers and lakes we're going to lose to agricultural pollution in the interim," chief executive Bryce Johnson said.
"Once you get into a slippery slope of allowing some streams to go, you're really undermining the brand," he told ONE News.
Gray Beagley is a farmer who is keen to keep waterways around his property clean.
But the Woodville farmer says there are others who aren't.
"I am sure there is still a very small percentage that need a good kick in the pants," he told ONE News.
Environment Minister Nick Smith issued the national policy statement on fresh-water management in May, saying it gave clear directions to councils on the importance of improving water management.
At the time, Green Party co-leader Russell Norman accused Smith of "taking the teeth" out of an earlier version recommended by a board of inquiry.
In the Cawthron report, resource economist Jim Sinner said if councils acted promptly, the decline in water quality could be stopped.
"However, experience suggests this is likely to take at least three to five years, and councils are allowed to take until 2030. Despite the national policy statement, the condition of New Zealand's lakes, rivers and wetlands is likely to decline for several more years and possibly much longer."
Yesterday, Smith said Fish & Game's criticism was "disappointing" and a return to a combative approach as signs of a more co-operative approach emerged.
"They're out of step with the rest of the community, who don't want more old-style 'dirty dairying' rhetoric."
The 2030 deadline was backed by the original board of inquiry, he said.
"They can't have it both ways, they can't criticise me for not following the board on one hand and criticise me for following it on the other."
The time frame was necessary because many resource consents ran for 15 to 20 years.
"Yes, 2030's a long time. But frankly, fixing water quality is going to take that length of time. I do not accept that there are going to be ongoing deteriorations," Smith said.
Smith this year announced a $264.8 million cleanup programme, saying improved water management was needed to allow the economy to grow.
In 2009, the Cawthron Institute gave the Manawatu River the worst rating of 300 waterways in North America, Europe, Australia and New Zealand.
The river was described as one of the most polluted in the Western World.
Johnson said poor policy had already seen 90% of lowland rivers and 50% of lakes classified as polluted.
"Leaderless fresh-water management policy, combined with the Government's $430m push for irrigation and intensive agriculture expansion, suggests the future for our iconic waterways and the 100% Pure brand is pretty gloomy."
Fresh-water ecologist Mike Joy said the policy would not help water quality, as it did not take steps to reduce intensive dairy farming.
There were six- and-a-half times as many cows in the South Island as there were six years ago, he said.
"No natural system can support that number of cows."
Many rivers, including the Manawatu, Rakaia and Waikato, were under threat, he said.
Federated Farmers water issues spokesman Ian MacKenzie said farmers were as keen as any group to improve water quality.
"Nobody wants to see Lake Taupo turn into a cesspit."
However, pollution came from many sources, including industry and urban development.
"This just seems to be grandstanding."
Labour's water spokesman, Brendon Burns, said the report made a mockery of Government promises to improve water quality.
"Nick Smith has ripped the guts out of the inquiry advice, and ... his handling of this actually means water quality across our streams, rivers and lakes will continue to get worse."
Smith said Labour did not even have a national policy statement. "In their nine years in office they didn't do anything about fresh water."
"Nick Smith is well known for political bluster but he cannot back out of this one. As a trustee of the Cawthron Institute he knows it enjoys a huge reputation. The only honourable course is to resign his portfolio and signal his own frustration with his Cabinet's pro-growth cabal headed by the Prime Minister," Burns said.
He also said Prime Minister John Key's reputation was damaged by the report.
"He recently told the BBC our water quality was second to none, and when quoted a Massey University scientist's opposite view, replied that was just one scientist's opinion. The Cawthron Institute's report on the Cabinet's NPS adds more reputable scientists to those who say publicly that New Zealand freshwater quality is poor and getting worse."
"The Labour Party, which commissioned the Board of Inquiry's report, is committed to implementing its NPS to ensure water quality improves and does not continue to deteriorate as would happen under a re-elected National Government," Brendon Burns said.