Andrew Curtis: Let's debate pros and cons of irrigation

Andrew Curtis

Mike Joy's recent commentary around dams in NZ doesn't tell the full story.

I agree with his headline - Agriculture must be clean and sustainable - and his statement about it being "crucial that, in the irrigation debate, there is even-handed coverage of pros and cons". Disappointingly, Joy chose a different approach - one that was misleading and often lacked context.

When Joy writes of dam removal in the United States, his comments lead readers to conclude that this is being done because of their "negative effects". In fact, where dams have been removed, it is largely because they have come to the end of their serviceable life.

Government agencies have also begun a programme of rationalisation, which will see some dams upgraded and modernised to meet new performance standards and others deconstructed.

Dam building has come a long way since the early 20th Century and many issues that have historically arisen from these dams can now be managed through expert design. When you exclude this side of the dam story, you can hardly call it "even-handed coverage".

Joy's statement that "165 scientific papers on dam impacts ... found that 92 per cent of them reported declining or negative ecological measures as a result of dams "omits a key fact: that many of these papers analysed dams in the developing world where there are often no, or at the very best, limited environmental considerations prior to their construction. This is not the case in NZ - where we now have some of the most robust environmental legislation in the world.

His statement that "dams lead to intensification" is no longer true in New Zealand. Under the Freshwater Management National Policy Statement, New Zealand now has an environmental limits regime for both abstraction of water and nutrient discharges.

For developments like the Ruataniwha, the end users will be subject to nutrient loss limits that they must manage within. The dam also has to abide by strict flow conditions. These requirements are legally binding - they are written into the consent conditions for the dam.

Lastly his statement that dams lead to reduced resilience is a nonsense. I've never once heard an irrigator supplied by water from the Opuha dam state they were more resilient under the previous boom/bust dryland scenario - despite the restrictions of recent times.

Joy seems also to have forgotten that without the Opuha dam, the Opihi River would have run dry - resulting in mass fish kills. Instead, the dam augmented the river and it was used as a safe haven by Fish & Game staff for fish they had rescued from other drought-stricken rivers.

There is no one size fits all for dams in New Zealand - in some catchments, smaller, farm-scale water storage is the best solution; in others, it's larger dams. All water storage feasibility projects start with an open book and from this, catchment-specific solutions are developed. All environmental, social, economic and cultural impacts must be considered as directed under the Resource Management Act.

We welcome debate on these issues, but what we don't like is having to wade through biased and agenda-based articles that distort the truth and do not, as Joy purports, provide "even-handed coverage of [the] pros and cons".

Take the recent paper from the University of Oxford School of Geography and Environment, which looked at 217 scientific papers on dams. It found there was a huge bias to the negative; rarely were the long-term benefits looked at and information provided by dam proponents was often excluded.

As an industry-led organisation, Irrigation New Zealand and its members would value the opportunity to debate the pros and cons of irrigation with Joy.

It would be a great opportunity to allow our communities to understand all viewpoints and to make up their own minds, based on robust, even-handed information.

Andrew Curtis is CEO of IrrigationNZ