Greenpeace activists and health experts have been bluntly told there will will be no national limit on the number of dairy cows allowed.
A new Greenpeace report, titled Sick of too many cows, was unveiled in Parliament grounds today, with support from the Canterbury Medical Officer of Health, Alistair Humphrey, and the Public Health Association.
The group sought a block on government funding for big irrigation projects and a reduction in the number of cows allowed.
Dr Humphrey said the Greenpeace report echoed his own research on water.
"Nitrate levels have increased across Canterbury to the point where midwives and GPs are having to provide advice to pregnant women on testing shallow bores.
"And of course we're all aware of the problems with algal blooms and declining water levels."
But Environment Minister Nick Smith said he disagreed.
"There are areas of New Zealand where we cannot have additional intensification of agriculture.
"What would be wrong though, is to take a blunt national ban or cap when there are other areas where it is quite possible to have expansion, without a negative impact."