Some Canterbury the rivers and streams are too polluted to swim in and the interconnected underground waterways are increasingly toxic. Most of Canterbury relies on these sources for drinking water and this situation did not develop overnight. It has been known and ignored by the Canterbury Regional Council for decades.
To find how that happened we have to go back more than thirty years to the beginning of what was called the “white gold rush; the unprecedented expansion of the dairy industry. Driven by high export returns for dairy exports, corporate investors, banks and financial lending institutions encouraged largely unregulated expansion of dairying throughout New Zealand.
In the mid-1980s New Zealand’s dairy herd was about 20,000 milking cows. By 2005, that had increased to more than 5 million cows. By 2009 it was obvious waterways needed protection from dairy pollution and the Canterbury Regional Council commissioned a Canterbury Water Management Strategy to be drawn up with input from farmers, stake holders and the general public. The majority of the more than 3000 submissions asked for regulations to prevent further pollution of natural waterways. Many farmers however said they could clean up the rivers voluntarily without the need for strict regulation. Other farmers, usually second and third generation farmers, realised the seriousness of the situation and have significantly modified their operations to reduce pollution. None of them however were doing anything wrong or anything they were not allowed to do. It was the failure of the regional council alone to properly regulate the system that created a massive problem
When the newly elected regional council of 2010 attempted to draft regulations to stop the pollution, farming lobby groups persuaded the Government to dismiss the councillors and replace them with commissioners on the spurious grounds that they were taking too long to develop a water management plan.
The commissions set about facilitating access to water for irrigation and making more land available for further intensification of agriculture and the damage continued. The commissioners remained in power for almost ten years and by that time (2019) New Zealand dairy cattle numbers had increased to 6.3 million and the Canterbury dairy herd had increased to about 1.2 million. Today the national herd is down to about 4.8 million and the South Canterbury herd is about 260,000, the highest since records began.
New Zealand’s almost 5 million cows produce approximately 21 billion litres of milk each year of which about 95% is exported as various dairy products. Those same cows also produce about 91billion litres of effluent all of which stays here to eventually pollute our waterways. Those same cows drink between 40 and 70 litres of water each a day depleting some waterways to almost non-existence. Many of South Canterbury streams are now “over-allocated” and have been for decades. That means consents have been issued to take more water than the legal allowable maximum without destroying the stream.
The success of dairying has brought a significant cost to the rest of the community with rivers, a previous generation of children swam in, regularly too polluted to allows dogs to swim in and aquifers overloaded with toxic nitrates.
In September this year an Ecan Water Quality for Contact Recreation annual report recommended permanent warning signs against swimming in the Pareora River at Pareora Huts, in Lake Opuha at the Ewarts Corner boat ramp, and in the Waihao River at Black Hole.
More serious is the increase in nitrates in aquifers used for drinking water. Nitrates are a form of nitrogen, an essential component for plant growth. Natural levels of nitrates for New Zealand groundwater range from 0.25 mg/L to 3.5 mg/L. This is a tiny amount given that one milligram is a millionth of a kilogram but such is the toxicity of nitrates that the international maximum level for drinking water is a mere 11.3mg/L.
In 2002 nitrate concentrations in Canterbury 942 wells exceeded that level. By 2023 59% of monitored sites showed increasing nitrate concentrations over the previous 10 years, up from 43% in 2022.The alarm bells should have wakened the dead.
Nitrates can cause blue baby syndrome, or methaemaglobinaemia. This is a potentially fatal condition caused high nitrate levels in the drinking water of pregnant mothers or the bottle formula fed to a baby. It has the effect of binding to haemoglobin, the oxygen-carrying pigment of the blood. A newborn baby can become starved of oxygen, turning blue around the mouth, hands and feet in four weeks. Very few fatalities have been reported but there are suggestions that some unexplained sudden infant death cases may have due in part to nitrates. The possibility that nitrates in drinking water below the 11.3mg/L is one of the contributing causes of bowel cancer in still under investigation.
Last year the water supplies of two South Canterbury communities was unfit for human consumption through the presence of unnaturally high nitrate levels. Selwyn District Council has budgeted more than $5 million to find an alternative drinking water source. If they find one it will cost an estimated $400 million to develop.
Also last year in the Waimate district a small rural community of about 600 people could not use their local council managed water supply when nitrate level exceeded the 11.3mg/L. The estimated cost of denitrification, if it is practical, range from $500,000 to $750,000 plus ongoing operating costs of about $20,000 annually. All of these costs will be paid by district council ratepayers who played no part in creating the problem.
Astonishingly Ecan is currently considering applications from a Twizel dairy farming operation to renew consents to spray irrigate 19 tons of nitrogen onto about 560 hectares annually. When these consents expire is the time to reduce or modify them, not grant them for a further twenty years or more. The legacy of our inept regional council will take millions of dollars and decades to undo even if we stop discharging nitrogen tomorrow.
Tom O’Connor is a retired investigative journalist, former dairy farmer, and former political opinion columnist for Stuff.