Regional councils say new research shows that New Zealand's river water quality is improving - not deteriorating as critics have claimed.
A website set up to monitor the water quality of rivers around the country shows nitrogen levels remain constant and phosphorus levels are actually dropping.
A representative for the councils, Fran Wilde, said this shows the state of the country's rivers is improving.
But scientist Mike Joy has questioned the data, and said the testing regime and 10-year measurement period has not been in place long enough to draw conclusions.
Dr Joy believes the councils are just trawling data to scrape out a good message.
James Renwick, an associate professor of physical geography at Victoria University, said for many environmental indicators there is very little data, as funding for making measurements is often hard to come by and observing systems and networks expensive to maintain.
So, while 10 years' data may not be as long a time series as people would like to draw robust conclusions and develop policy from, it is probably all the country has and is a lot better than having no data at all, he said.
Green Party environment spokesperson Eugenie Sage said while it is good to have a website to view statistics, there is no significant commentary surrounding the data provided.
For New Zealand to restore rivers to a condition that everyone can be proud of, there will have to be more of a commitment on a national level to find out just what the state of our environment is, she said, and that will require hard numbers backed by analysis and commentary that people can understand.