Fonterra has responded to calls for it to take action against suppliers who pollute waterways by saying it can impose financial penalties on farmers or refuse to collect their milk - but confirms it has yet to do so.
The company's sustainable production manager John Hutchings said yesterday the company was working with "several suppliers" throughout the country to help them improve management of dairy shed effluent.
"We're dealing with a number of suppliers on a one-on-one basis. At some point, we may need to name them, but at the moment we are working with those suppliers and making progress."
Environment Southland compliance manager Mark Hunter expects Fonterra to take action against five parties convicted last week of effluent discharge breaches, which could ultimately mean refusing to collect milk.
"For them to be prosecuted twice, and found guilty on both occasions, that to me implies a certain amount of intent," Mr Hunter said.
But the growth of dairying in the region was not mirrored by more discharge breaches, he said.
Green Party co-leader Russel Norman this week criticised the Otago Regional Council for protecting the names of alleged water polluters in the region, but the council maintains it was abiding by legal policy.
Dr Norman called for harsher punishment of waterway polluters throughout New Zealand and claimed to have received from a dozen regional councils the names of people or companies prosecuted for polluting.
"Keeping secret the names of a small minority who offend against the council's pollution rules gives an impression the council is firmly on the side of polluters rather than the wider community and the environment.
Names of the worst polluters should not only be supplied to us [the Green Party]; they should be listed on the council's website and available to everyone, so there is real pressure," Dr Norman said.
ORC chief executive Graeme Martin said the council's policy was not to additionally name those who had been through courts or paid fines.