A report from the Southland regional Council on region's water quality concludes more information is needed to explain whether water is safe to play in, drink, and gather food from.
The Our Health report is the first in a series of four into the state of Southland's freshwater environment.
The dairy industry and the Green Party have interpreted figures and findings in the report in contrasting ways, .
DairyNZ says the report paints an overly negative picture of the region.
The industry group's water quality specialist, Shirley Hayward, says people could misread the report, because the points raised in it don't match individual water quality parameter rankings or the results of biological monitoring.
She says some freshwater systems are degraded, and DairyNZ is addressing the dairy industry's contribution to this.
However, she says pristine environments are not realistic expectations in areas of land development.
Green Party co-leader Russel Norman says the report clearly shows 89% of Southland rivers are of poor quality and stronger rules are needed to protect waterways.
He says scientists have linked the decline of water quality in the region to the intensification of pastoral farming, and regional councils have proved they can't stop the polluters.
Dr Norman says national standards of clean water are needed across the country, as part of a plan that also includes a fair charge for irrigation water and financial support for water clean-up initiatives.