OPINION: Parliamentary Commissioner for the Environment Jan Wright writes to correct some interpretations of her water quality report.
Since the release of my recent report Water Quality in New Zealand: Land use and nutrient pollution, I have listened to and read the commentary that has followed with great interest. It is encouraging that so many are engaging in this very important issue of the quality of the water in our rivers and streams, lakes, estuaries, and aquifers.
The scale at which land used for sheep and beef farming continues to be converted to dairy farming is particularly marked in Southland and Canterbury. Unfortunately, such change leads to greater losses of nitrogen and phosphorus from land into water.
The impacts of this nutrient pollution can include excessive growth of weeds, slime and algae. One need look no further than the Waituna Lagoon to see the effect that land use change can have.
However, there is no question that dairy farming is of great importance to the economies of these two regions, and this creates a dilemma for all New Zealanders.
Recently some of the commentators have interpreted aspects of my report incorrectly. This is not surprising as the underlying science and modelling is complex.
I would like to take the opportunity to clear up three main points.
First, it has been said that the modelling does not take account of existing and planned mitigation on farms. This is not correct.
The modelling assumes that by 2020, all dairy farms will comply with the Sustainable Dairy and Water Accord - a great initiative from the sector this year. Also assumed is that new dairy conversions are all best practice, along with reduced nutrient losses from improved stock genetics and fertiliser management.
Second, there has been some confusion about the fact that my report did not take into account any major new policy initiatives.
It is true that the effects of particular policies like the Horizons Regional Council One Plan were not modelled. However, as explained above, the modelling does envisage greatly improved mitigation on dairy farms. It was generous in this respect, especially in regard to mitigating nitrogen losses - the solubility of nitrate makes nitrogen "elusive" and much harder to mitigate than phosphorus.
Third, my report has been dubbed by some as a worst case scenario.
This is not so.
Rather it is a scenario of significantly improved mitigation, combined with more of the large scale land use change that has accompanied the changing economics of farming.
The model predicted that on average, 31,000 hectares of land would be converted to dairy farms each year between 2008 and 2020 across the country.
The latest statistics from DairyNZ show an average increase of 40,000 hectares each year over the last four years.
The level of engagement and debate that has followed the release of my report has been heartening. There has been agreement that 'diffuse nitrogen" is a major challenge for the country, particularly in some regions including Southland.
The principle that the nutrient loads on waterways are very influenced by how the land is used has not been questioned. And I do welcome and recognise the efforts being made by farmers, the dairy industry, and councils to address the issue of nutrient pollution.
In my role as an Officer of Parliament, I have the privilege and responsibility of independence. In all the work my staff and I undertake, we approach each issue with an open mind, and place high value on rigorous analysis of the available information.
Sometimes the conclusion of an investigation is a win for the economy as well as a win for the environment. My 2011 report on evaluating the use of 1080 was such a win-win. The pesticide is not only used to kill the possums, rats and stoats that do so much damage to our native plants and birds, but is also used to kill possums and ferrets because they are vectors for bovine tuberculosis. I would have been very pleased if the outcome of the modelling work I commissioned for the water quality report had delivered good news for both the environment and the economy. Instead it shows the need for all of us to work more actively together on this difficult problem of the influence of land use change on water quality.
I encourage all those interested in the challenging issue of water quality to read the report. It can be downloaded from www.pce.parliament.nz, and printed copies are freely available on request.
Jan Wright is Parliamentary Commissioner for the Environment.
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