NIWA have put out a release summarising the trends from 20 years of monitoring river water quality.
The National Rivers Water Quality Network collects data from 77 sites across the country. The dataset they have is the longest and most wide reaching water quality data set in the country.
What is shows is not a great surprise: water quality in natural catchments is good; water quality in pastoral catchmetns is bad and getting worse; point source pollution is improving (eg sewerage treatment plant outfalls).
Doesn’t matter how many times Federated Farmers denies it, the truth keeps coming back:
However, nitrogen and phosphorus levels have increased at many sites due largely to ‘diffuse pollution’ from pastoral farming – with increased stocking rates and use of fertilisers, and conversion of land used for sheep/beef farming to dairy or deer farms.
Which makes you wonder why we don’t have a moratorium on conversions in at-risk catchments until we have some controls in place to deal with dairy conversions.