From the tasmaniantimes.com
An article by the late Bill Benfield.
See our article on the Manawatu River here.
The Manawatu is an interesting comparison. Not only is it often cited as one of New Zealand’s dirtiest rivers, research by the Cawthron Institute in Nelson showed it to be one of the dirtiest in the western world. In an item from the Dominion Post of 26/11/2009, it cites Dr Young of Cawthron claiming that a system measuring oxygen changes in water (un-defined) show the Manawatu has a reading of 107, nearly twice that of the next worse, a river near Berlin just below a sewage outfall, where the reading was 59. Dr Young cited leaching farm nutrient and treated town sewerage, with agricultural use, i.e. nitrogen run off, being most of it.
Looking to maps Google Earth, it is obvious that there is a lot of human settlement, hill country farming, some forestry and, in the valleys, long strips of pastoral farming (including dairy). There is just not the weight of dairy to support Dr Young’s claims. As well, there are many significant towns, and they cannot be ignored, this is where the authors of this review exhibit a bias. It starts with the description of the sewerage discharges; they are described as treated. In fact, the city of Palmerston North is operating a non-complying system on a temporary consent till 2020; it is the biggest urban discharge consent and for up to 46,600 cubic metres per day of only partially treated sewerage. Horowhenua District Council has also admitted dumping 5.1 million litres of “partially” treated sewerage into the Manawatu which they also admitted contained tampons, condoms and toilet paper!
Untreated storm-water is not even mentioned. It is all the rubbish from the roads and gutters, fuel spills, dead animals, garden rubbish in the drains, sometimes even raw sewerage from old combined connections. There will also be leachates from landfill rubbish sites – it’s everything.
In all, from the towns, Eketahuna, Pahiatua, Woodville, Dannevirke, Ashurst, Fielding, Shannon, Palmerston North and so on have a combined sewerage discharge consent of 75,600 cubic metres per day. To that, we can add industrial discharges from milk processor Fonterra, New Zealand Pharmaceuticals and Tui Breweries.
By claiming “sediment washing into the river from overgrazed farms or eroding countryside”, the authors ignore some of the bigger generators of silt. Forestry is certainly a major contributor, both in clearing the land for planting and at time of harvest. Another is cross blading and bulldozer work in the river bed. I’m not actually championing dairy farmers, but I think it is reasonable to say that there is a lot more involved in the Manawatu than agricultural runoff – aka “dirty dairy”.