Have a guess, just with a gut feel… do you think the Waikato river is one of world’s TOP FIVE cleanest rivers?
A stoush between leading scientists has bubbled to the surface over the state of the Waikato river.
Last month, the newly appointed chief scientist of the Environmental Protection Authority, Jacqueline Rowarth, drew the ire of some scientists when she announced the river was in the top five cleanest rivers in the world.
Ms Rowarth, wearing her former hat as a Waikato University agribusiness professor, reportedly made her comments to 180 farmers at a Primary Land Users Group meeting on 3 October.
But the Freshwater Sciences Society said her comments were wrong.
The Society’s president Marc Schallenberg said Ms Rowarth is basing her statements on nitrate data released by the OECD over the 2002 to 2004 period.
He said that data, which samples about 100 rivers worldwide, shows the Waikato sat in the top 5 percent of rivers then.
Top 5 of the 100 chosen. Not top 5 of all rivers. That makes a difference.
Mr Schallenberg said using the OECD data is problematic as it only takes samples from the mouth of the river and not areas like estuaries which can show significantly different results.
Ms Rowarth’s later comments in an letter to NZ Farmer that E Coli in the river would pass the European Union’s swimability test were also wrong, he said.
He said she used median values and not maximum values to assess the data.
“If you look at the Waikato river data, the raw data, you see that in the lower river, it does exceed the swimability standards of both the European Union and in the New Zealand standard quite often.”
“Again, it was the wrong message and the wrong interpretation of the data and the Waikato river doesn’t always meet swimability criteria.”
Mr Schallenberg said Ms Rowarth’s comments undermine the fresh water restoration work of iwi, government, and community groups.
A professor of biological sciences at the University of Waikato, David Hamilton, said the Waikato doesn’t make the top 30 cleanest rivers in the country, let alone overseas.
He said nitrogen concentrations differ widely between the mouth of Taupo to Port Waikato.
During that path, there is a 10-fold increase in nitrate and nitrogen generally, he said.
“The volume of the river roughly increases about 2-and-a-half to three times, so it’s quite a significant shift.”
I’ve drunk water from a number of rivers over the years without any need for treatment. I would never drink the water from the Waikato without UV, filtration or chemical treatment.
Which is, of course, what a lot of Auckland do.
Those scientists must absolutely love their new “chief scientist of the Environmental Protection Authority”. She seems to be into corporate smoke screens instead of scientific endeavour.