In the decade or so since the dairy industry slowly began to acknowledge the link between its rapid growth and deteriorating water quality in our rivers, glacial progress has been made towards addressing the issue.
First, there was the Dairying and Clean Streams Accord, which encouraged farmers to fence creeks, comply with resource consents, minimise nutrient leaching and put culverts over streams where cows crossed. But the document was toothless and the pace of improvement sluggish.
This year, a more ambitious version of the accord was implemented, with farmers talking of the need to “up our game” and ensure dairying works for all New Zealanders – including, presumably, those who want to swim and fish in our rivers.
Meanwhile, the Government has inched towards the implementation of concrete standards for water quality. Where there was previously a regulatory vacuum there is now a national policy statement requiring regional councils to maintain or improve the quality of waterways in their areas. And this month the Government released a discussion document that proposes to back up that aspiration with a set of national “bottom line” water-quality limits.
Although there is argument among the experts as to whether the proposed standards are tough enough or measure the right things, it is a step in the right direction.
But as all of this has proceeded at a gentlemanly pace, the dairy juggernaut has continued to march across the land and, on its current trajectory, promises to bequeath future generations increasingly degraded rivers.
A report this week from the office of the Parliamentary Commissioner for the Environment spells out the dilemma facing New Zealand in dealing with the environmental impact of our most important industry. We can convert increasing tracts of land from sheep and forestry to dairying or we can have clean rivers, but we can’t do both.
Commissioner Jan Wright’s investigation shows a clear link between large-scale expansion of dairy farming and increased stress on water quality. Even when measures are taken to minimise the impact – by planting riverbanks and spreading dairy-shed effluent as fertiliser, for instance – the conversion of land to dairy farming generally results in more degraded waterways, she concludes.
Her report is based on work with respected independent economic firm Motu and scientists from Niwa. Essentially, two well-established models have been joined together to predict the likely future expansion of dairying and the consequent impact on waterways.
One of the key pollutants is nitrogen, which mostly comes from animal urine. When cows urinate, they dump more nutrients onto the soil than it can take up through grass growth. The excess flushes into groundwater and streams, where it causes slime, algae and weed to grow and, in the worst cases, can make the water toxic. The other key pollutant is phosphorus, which ends up in rivers stuck to soil from eroding banks and hillsides and also fuels excessive weed growth.
Between 1996 and 2008, 300,000 hectares of sheep and beef country was converted to dairying – mostly in Canterbury, Otago and Southland. It’s no coincidence that nitrogen loads in rivers in these regions increased most dramatically. Phosphorus run-off also increased the most in those areas.
All things being equal – with continued strong dairy prices and the ongoing expansion of irrigation – the modelling predicts the amount of land given over to dairying will increase by a further 370,000 hectares between 2008 and 2020. It also shows that nitrogen loads in waterways in virtually every region will continue to rise, particularly in the three fast-growing dairy regions of Canterbury, Southland and Otago.
And positive as it is, mitigation efforts such as riparian planting and stream fencing are not enough to offset the massive increase in nutrient run-off from large-scale conversions, Wright says. Cutting down plantation forests and growing cows instead leads to 10 times more nutrients flushing off the land.
The implications are plain to see. More dairying will mean declining water quality over the coming years. There is no cute “win-win” where both the environment and the economy gain from burgeoning cow numbers.
Fortunately, steps are finally being taken to establish enforceable standards aimed at maintaining and improving water quality. We now have the beginnings of a regulatory regime to control the volumes of nutrients ending up in rivers. But it is clear that the time for gentlemanly progress is over: Wright’s report is an urgent call to action.
We can convert increasing tracts of land from sheep and forestry to dairying or we can have clean rivers, but we can’t do both.