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That comment was made yesterday by Dr Grant Blackwell, the principal science adviser for the Parliamentary Commissioner for the Environment.
Compared with many other countries, New Zealand's freshwater was generally of good quality and did not have to be shared with other nearby nations, he said in a talk to the University of Otago's 49th annual Foreign Policy School.
It was not the fault of any single industry or of a single generation, but freshwater was becoming a ''scarce resource'', he said.
In recent years, hundreds of thousands of hectares previously used for sheep and beef farming had been converted to dairy farming.
This had resulted in ''significant increases in nitrogen and phosphorous levels'' in waterways, and corresponding declines in water quality.
Central and local government had started to develop new policies, plans and rules, but their effectiveness would depend on whether they were ''based on an understanding and acceptance'' of the relationships between land use change and water quality.
If they were not, ''there are risks for both our freshwater environment and our economy'', he said.
Dr Blackwell said the approach of the Parliamentary Commissioner for the Environment was ''not about blame'' but to make available ''fundamental ideas and information'' to politicians and the community.
An ecologist with a PhD from Massey University, Dr Blackwell also undertook research for several years at the University of Otago Centre for Sustainability.