Keith Woodford says truth is the first casualty in water debates

Remnant mountain totara in catchment high above Lake Forsyth (Annette Woodford)

By Keith Woodford*

Recently I dipped my toes gently into the debate about how to use water fairly for all New Zealanders. I did so knowing that to say anything about water is like stirring up a nest of angry wasps.  

Both environmental and economic development protagonists are typically convinced their cause is ‘noble’.  Accordingly, many protagonists organise the ‘facts’ to support their prior-determined position. The term for this is ‘noble cause corruption’’, where ends justify means.

It is not only individuals who act this way, so do organisations.

In this environment, truth is the first casualty. Regardless of whether the underlying driver is ‘noble cause’ or simply ignorance fuelled by self-interest, the outcome is the same. Debates become tribal shouting matches.

One of the problems with water is that the true facts are almost always complex, Even the so-called experts are learning on the job, and can be wrong in their assessments.

Science has a way of trying to deal with such situations. It is called the scientific method. Hypotheses are developed from logic and observation, and these hypotheses are tested by measurement and experimentation. When dealing with complex systems, scientists often use models to help them interpret the interacting variables.   

However, the idea that science can ever prove things is a dangerous assumption. It was Karl Popper, the famous 20th Century philosopher of science – who actually spent years at Canterbury University during the 1940s, having fled from Nazi Germany, and before finally settling in Britain – who encapsulated the idea that science advances by showing that existing perceived knowledge is wrong; disproving theories rather than proving them.

All of this might sound very theoretical, but it is also highly relevant to our water challenges here in New Zealand.  We need to base our thinking on known science and known fact, but always willing to re-assess our positions as more evidence comes forth.   That willingness to reassess also applies to scientists – they too get locked into positions and they too can suffer from noble cause corruption.

Somewhere in amongst this there is also a precautionary principle. In essence, the precautionary principle says that it is not easy to unscramble an egg.

I am going to use two water examples that have been in the news in recent weeks here in New Zealand, one being Lake Forsyth and the other the Selwyn River. They both happen to be in Canterbury which is where I live, and so I know a little about them.  However, there are undoubtedly equally good examples from all over New Zealand, where a mix of ignorance and noble cause corruption leads to issues being simplified and distorted, and where so-called facts are used to bolster pre-determined positions.

Lake Forsyth (Wairewa) is in the news because of massive outbreaks of Cyanobacteria, creating a thick green scum. The lake lies adjacent to the Little River township, and both sheep and dogs have died from consuming the water.

Lake Forsyth used to open naturally to the sea on the southern side of Banks Peninsula.  That changed way back in the 1800s as a result of changing sea currents and the deposition of shingle dragged north from the outlets of the big alpine rivers.  The fundamental cause behind the changing shingle deposition – it may even have been precipitated by the huge Alpine Earthquake of 1717, with its consequent release of shingle over the subsequent 100 years, and perhaps also by uplift of the land itself – is conjecture. What is clear is that the closing-off was not caused by man, either directly or indirectly. This was simply nature doing its thing.

However, that is just the first part of the story, because humans have had a big impact on Lake Forsyth. This occurred through 19th Century deforestation and logging of Banks Peninsula, and conversion of land for sheep grazing. This in turn led to erosion, with the sediment ending up in Lake Forsyth. As a consequence, Lake Forsyth is now shallower than before.  Shallow lakes warm up more in summer than deep lakes, and that too has been important.

Starting in the 1950s, there was a lot aerial topdressing of the Banks Peninsula grasslands. Inevitably, there was phosphorus runoff from rainfall events.   

Putting all of these things together, the preconditions were all in place for outbreaks of the toxic bloom from Cyanobacteria, and these have indeed been occurring in recent decades. All it then took was nature to do its thing in 2013 and 2014 with flooding coastal rains which sent lots more phosphorus into those waters, to create the current crisis.

So what we see in Lake Forsyth is an example of what happens in complex ecosystems where nature and humans are both doing their thing. Note however, that in contrast to considerable media commentary, this has nothing to do with irrigation, nothing to do with dairying, and almost certainly nothing or at least very little to do with global warming.

Ecologists and local iwi are working to find solutions. With hindsight, and from a lake perspective, it would have been better if much of the deforestation of Banks Peninsula did not occur. But that egg was first scrambled 150 years ago. And yes, it would also have been better if the effects of phosphorus runoff from sheepgrazing lands had been better understood some 50 or more years ago.   Hopefully, the ecologists will find some answers, but solutions will not come easily.

The Selwyn River is a different story. It begins in the foothills of Canterbury behind the townships of Hororata and Coalgate. It flows all year back in those hinterlands but quickly disappears underground once out on the plains. It is only during wet years that it flows through to Coe’s Ford in the Ellesmere district, and then on to Lake Te Waihora (Ellesmere). 

However, the lowland plains of this catchment have historically had many springs which bubble to the surface.  And until recently this has usually been sufficient to keep Coe’s Ford with sufficient water to provide good swimming holes.

The springs in the lower Selwyn catchment have been in decline for more than 50 years. Lincoln University has its ‘Ashley Dene’ farm in this zone, and historically it was plagued by undercurrents which would well-up in winter and cause major flooding. Although the springs were originally marked on the farm maps, these were removed in the 1960s because they no longer existed. And at that time there was close to zero irrigation in the district. 

These undercurrents did make their presence felt again in the mid to late 1970s during a series of wet winters, but since then all has been quiet.

More recently, there has been extensive development of irrigation in the Ellesmere zone drawing water from shallow aquifers. There can be little doubt this has played a role in the current record low flows of water at Coe’s Ford. However, the pictures that I am seeing in the media of dry riverbeds elsewhere in this catchment are nothing new; it is the reason the Maoris called the river Waikirikiri – river of shingle.   And the point needs to be made that most of the irrigation in the Ellesmere district is for cropping, not dairying.

Although the winters of 2013 and 214 brought huge rains to Banks Peninsula, this was not the case on the adjacent plains. The last few winters have been very dry on the plains, and this is undoubtedly part of the story as to the current sad state of the Selwyn at Coe’s Ford.

There is hope that the waters of the Selwyn can be restored. Currently there are long-term restrictions on water abstraction from shallow aquifers. These aquifers do need to be treated differently than the deep aquifers. Also, the much-maligned Central Plains Water Scheme, sourced from alpine waters of the Rakaia, is expected to produce significant recharge to the shallow aquifers. But it is not going to happen overnight.

My closing thought is that science and rationality struggle in a superficial world which beats to 15 second sound bites, 140 character tweets, and dominated by media which are driven by sensationalism and the need to sell advertising.  Complex water debates do suffer in that superficial world.

*Keith Woodford is an independent consultant who holds honorary positions as Professor of Agri-Food Systems at Lincoln University and Senior Research Fellow at the Contemporary China Research Centre at Victoria University.  His articles are archived at