Skip to main content

A straight line is godless – the Ruamahanga River

Russel Norman MP
Russel Norman MP
russel [dot] norman [at] parliament [dot] govt [dot] nz (Email)

On Friday (11-2-11) I rafted down the Ruamahanga River with a group of locals from the Wairarapa as part of my Dirty Rivers Rafting Tour. We had people there from Rangitane o Wairarapa, Forest and Bird, the Greens, Fish and Game, Wai Not Go Green local enviro group, and other locals.

The Ruamahanga starts in the north eastern Tararua Forest Park and flows south through the Wairapapa landscape before coming out through Lake Onoke (Lake Ferry) into Palliser Bay. Along the way it picks up major tributaries such as Waihine, Waingawa and Waipoua. 

It starts with crystal clear water in the Tararuas but as it winds its way down it gathers pollution from agriculture and towns. The treated sewerage from Masterton, Martinborough,Carterton and Greytown all ends up in the river. In low flows these sewerage inputs are major sources of pollution (especially phosphorous) but they are overwhelmed in higher flows by all the nitrogen and faeces running in off farming, especially intensive dairying.

E.coli levels of 550 cfu/100 ml are dangerous, yet the Ruamahanga reached over 2000 cfu/100ml last February, following rainfall. E.coli is an indicator of faeces, human and animal, and means that there is risk from a wide variety of pathogens such as viruses (eg Hepatitis), protozoa (eg giardia, cryptospiridium), and bacteria (campylobacta, salmonella) etc.

We started on the edge of Masterton, near Henley Lake. One of the lake trustees told us about efforts to clean up the lake as it has been in pretty bad shape – and, after hearing about the rashes and spots that appeared on kayakers after they paddled on it, I wouldn’t recommend swimming there. The discharge from the lake didn’t look too bad on the day we went passed.

The water in the Ruamahanga had pretty good visual clarity where we started. The rivers are worst when there is a big rain after a dry period as all the faeces and crap washes in; after a long dry spell they can be full of algal blooms. The Ruamahanga seems to be currently benefitting from earlier rain.

Then we passed the Waipoua River junction. The Waipoua runs though some agriculture land before passing through Masterton itself and getting town and industrial pollution. Some locals use the river for swimming – one of those on board the raft knew of a local boy who had swum the Waipoua recently who got a scratch which had turned septic and he ended up in hospital for three days.

As we headed down it became clear that the river had been extensively worked over and straightened with bulldozers and graders as part of the ”flood protection” efforts of the Wellington regional council. The natural form of the river, with its meander and regular pools, was replaced by long straight sections with few pools and wide shallow flows. This reduced habitat for fish dramatically as it is the pools meeting the banks and vegetation that provide much of the habitat. And the bulldozers destroy habitat and nesting sites of birds along the edges of the river. Fish and Game are trying to get the regional council to pick up its game.

There were extensive efforts to hold the banks with willow plantings. There were also these strange arrangements with railway rails driven vertically into the bed of the river near the shore and connected by steel cables. The theory apparently is that the cables will catch debris in high flow events and protect the banks from erosion. These rails now stick out randomly in the river with random steel cables hanging off them and are a major hazard to navigation.

These flood and bank protection measures are really destructive to the river as a natural system. And seem pretty pointless and expensive. The ratepayers of Wellington and the Wairarapa are paying rates to destroy the ecology of these rivers in an effort to stop paddocks going underwater in big rainfall events and to slow erosion of a paddock next to a river. It’s a river coming out of a mountain range. It floods and it meandars and it moves about on the flood plain. If you have a paddock next to a river like this it will flood at times and erode at times. In fact the paddock was probably created, fenced off and claimed after a previous change in the river’s course meant that soil accumulated in that spot. We need some green engineering at the Wellington Regional Council; instead of throwing away millions fighting natural processes maybe we could think about how to work with them.

The Masterton wastewater treatment plant has been pretty controversial of late. The existing one is crap and needs replacing. This is the discharge plume from the current plant – what you can’t see is all the non-point discharge coming through the groundwater:

The Masterton District Council has opted for a new scheme that reduces some of the nutrient flow into the Ruamahanga (possibly up to 40%) but refused to sign up to a better system that reduced nutrient flow even further.

Cost seems to have been the major issue, though that was thrown into doubt when the  brain boxes at Beca Consulting admitted that the scheme they costed at $24m will actually cost $30m. The Council is building a system of border dykes next to the river – a flat field with raised edges into which the treated waste water is poured and it soaks into the ground. Some of the nutrient will be extracted by the crops grown in the field but a lot will simply diffuse into the river through the groundwater.

And just to prove how much heat there is in the Masterton sewerage issue, at the pullout point the ”Laird of Te Whiti” had left these signs for us….

As we jumped on the bus to go back to the cars this sign caught my attention…

But let’s not forget that while the sewerage treatment plant is the current flashpoint, intensive agriculture makes a huge contribution to the river pollution as well. That’s why we need ”Clean water rules NOW” – the Draft National Policy Statement on Freshwater Management that is sitting on Nick Smith’s desk and that he won’t sign off because it will upset the polluting industries. He claims the draft NPS is ultra vires (goes beyond the legal powers provided for in the RMA), but Justice Sheppard who wrote it clearly doesn’t think so, and Smith won’t release the legal opinion on which his claim is made....

Thanks to everyone who came along and especially thanks to Dave Woodcock from Wairarapa Outdoor Pursuits who provided all the gear and logistics.

^ Back to Top