New Zealand's dairy farmers have once again come under attack for dirty dairying.
A new report commissioned by Fish and Game New Zealand blames dairy farmers for the poor condition of many lowland waterways.
The report was conducted by the National Institute of Water and Atmospheric Research which reviewed the scientific research into lowland waterways.
Bryce Johnson from Fish and Game says the report shows they are in a worse condition than originally thought.
"It confirms that agriculture in particular is having a huge impact on water quality and we need to do something about it if we're going to add integrity to our clean green image," Johnson said.
Fonterra accepts that some dairy farmers could do better.
The dairy giant is drawing up new environmental standards for its suppliers such as ensuring streams are fenced off from stock.
"Of course it's important. At the end of the day housewives around the world who decide to buy our products do so on the basis of food quality, animal welfare and environmentally sustainable practices," Chairman John Roadley said.
But Federated Farmers accuses Fish and Game of damaging New Zealand's interests by waging their dirty dairying campaign.
"It is blaming the whole industry for maybe the actions of a few. The industry as a whole is actually making a big effort and if you look at the history we've actually done very well," Frank Brenmuhl, the vice chairman of Dairy Farmers New Zealand, said.
The report says dairying is likely to keep expanding, taking over a further quarter of a million hectares of land by 2010.