New studies suggest that the risks from nitrates in drinking water could be higher than previously thought. This will add to the list of concerns facing anyone living on the Canterbury Plains.
Why are nitrates a problem?
We have known for some time the risks of increasing nitrate levels in our water. The impact on fish, eels, and bugs living in our rivers and lakes is well understood. Nitrogen combines with phosphorus and light to grow algae. At low levels this provides food for aquatic life, but you can have too much of a good thing. Algal blooms can clog rivers, rob them of oxygen, and even kill off life completely.
Algal blooms are a massive turn off for anyone wanting to swim in a river and they can also turn toxic, which poses a threat to pets and children that might eat them. We are increasingly seeing these sorts of events all over the country thanks to warmer temperatures and higher levels of nutrients in our water.
Much of the increase in nutrients in recent years is the result of dairy farming. Dairy cows pee in far greater concentrations than the soil can use, so the remainder leaches into aquifers and rivers.
Canterbury is unique
However, what is happening in Canterbury is unique. The sheer scale and speed of change in converting land to intensive dairy farming combined with the stony soils mean a tsunami of nitrogen is heading into the region’s rivers and aquifers.
The nitrogen levels in fresh water in Canterbury are often far above the level that can trigger algal blooms. In many places, they are even above safe levels for wildlife.
Incredibly, some parts of the Canterbury Plains are now at high enough concentrations where human health is threatened. So called “blue baby” syndrome occurs when nitrate levels are so high that they prevent a baby’s blood from carrying sufficient oxygen. The Canterbury DHB is closely watching this problem and medical officer of health Alistair Humphrey has been raising concerns about it for some time.
But nitrate levels will continue to rise in coming years as we see the full impact of past land-use decisions.
It gets worse. Recent studies in Denmark suggest that nitrates in drinking water at much lower levels might pose a risk of colon cancer. The evidence is at an early stage but if it holds up, we can expect the World Health Organisation to lower the guidelines for acceptable nitrate levels in drinking water.
Such a change would pose real problems on the Canterbury Plains. Dairy cows would need to be reduced on a massive scale – far greater than current proposals to protect the environment.
Private profit, social loss
The current situation is already pushing the cost of private profit-seeking onto the public. Private citizens have been robbed of their right to quality drinking water and are being forced to buy bottled water or install nitrate removal systems at a cost of $2,000 per person. It is New Zealand’s equivalent of the sort of private profits and social losses that we saw during the Global Financial Crisis.
Sadly, the private profits haven’t even turned out to be particularly significant. Fonterra’s struggles have been well documented and the increased milk supply from places like Canterbury hasn’t made their job easier. Farmers have taken on large debts, betting on a high price for milk that hasn’t eventuated. Many dairy conversions have been carried out purely to pursue capital gain in land values.
Now, we face the massive challenge of transitioning an industry that is already struggling both economically and financially. The head-in-the-sand approach of the previous National Government isn’t good enough. The blunt regulation pushed by the likes of the Green Party will see farmers go under in huge numbers. The Opportunities Party has developed market-based solutions that reward farmers who innovate and farm in ways that don’t damage the environment. Only then can we improve the environment without sending farmers to the wall.