Otago University data analysis that has drawn a possible link between elevated levels of nitrates in the region and the Oceania dairy factory has been forcefully rejected by the company.
Using data from regional council Environment Canterbury (ECan), the university’s public health researcher, Dr Tim Chambers and colleagues, have raised questions about wastewater discharge from the factory at Glenavy and high nitrate levels in the surrounding community.
“Looking at well data obtained from ECan by Otago University … it looks like the Oceania Dairy Factory could be playing a part with its nitrogen-rich wastewater,” Chambers said.
But he said further work needed to be done “to establish the specific cause and the contribution of any land use practice.”
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Emergency drinking water supplies have been in place for the Lower Waihao and Waikakahi East water schemes in the district since the national drinking water standards were exceeded in August.
The Waimate District Council is to add denitrification technology to a treatment plant it is building, expected to be commissioned in May or June 2023, and has advised the more than 600 affected residents to use tanked-in water until then.
Chambers said data from environmental monitoring of bores in the area showed the “steady increase” in nitrate in local wells corresponded to the factory being granted consent to discharge to land in 2013.
“There is also an increase in calcium and hardness which indicates dairy factory waste – predominantly whey – is potentially contaminating the wells,” he added.
Greenpeace senior campaigner Steve Abel echoed caution.
“The extent to which Oceania may be culpable is yet to be established, but it’s really important to ask the questions.
He said the increasing presence of calcium in the wells “could be the smoking gun to the dairy factory playing a part in this nitrate-spike.”
“There’s more work that needs to be done on how much of a role it is playing….”
Oceania Dairy branded the claims “irresponsible.”
Logan Hanifin, the factory’s general manager, said it was “extremely disappointing to see an organization such as Greenpeace” making claims “that could divert much-needed attention away from determining the actual causes of elevated levels of nitrate in Canterbury’s drinking water.”
“ECan has completely repudiated Greenpeace’s claims, advising that elevated levels of nitrate are likely to have been caused by flooding during the extreme weather event we experienced over winter.”
Hanifin said the water supplying to the affected areas is up hill from the factory, and noted the company “is not linked to town water supply”, sourcing its water from five bores surrounding the factory.
“We test the bore water monthly for nitrate levels. No elevated levels of nitrate have been detected in these bores which are in very close proximity to land on which our treated wastewater is dispersed,” he said.
Ingested nitrates are known to have serious health impacts, including potentially fatal to bottle-fed babies, causing low birth weights and neural tube defects and being linked to colorectal, or bowel, cancer.
Nitrates can not be removed by boiling or conventional filtering.
The New Zealand Drinking Water Standards Maximum Acceptable Value (MAV) for nitrate in drinking water is 11.3 milligrams per litre (mg/l) of nitrate-nitrogen (or 50mg/l of nitrate).
Campaigners argue the limit – which is based on 1958 World Health Organization guidelines for preventing infant death from methaemoglobinaemia (blue baby syndrome) – do not protect from other possible health impacts with some research pointing to dangers connected to lower nitrate levels.
Chambers, who will speak at Tuesday’s public meeting at the Glenavy Hall, has published research on the health impacts of nitrate including a study estimating 100 cases of colorectal cancer and 40 deaths per year in New Zealand could be caused by the contaminant.
Stats NZ figures show a sevenfold increase in synthetic nitrogen fertiliser use and a 10-fold increase in dairy intensity across Canterbury over the past 30 years has been accompanied by increased nitrate contamination of drinking water.
Chambers said he and his team are researching causes of elevated nitrate levels across the country, and were interested in the Lower Waihao and Waikakahi East situation both because the MAV had been breached and due to the “unusual water chemistry” between the drinking water source and other bores.
Calcium occurs naturally in drinking water, usually at relatively low levels, but Chambers said the Glenavy data showed a three-fold increase in calcium since 2012, despite levels remaining relatively consistent during the period of agricultural intensification from the 1990s on.
Chambers said that makes it even more important for further investigation to pinpoint the cause.
“We’re trying to create a national groundwater map for nitrate contamination, and, for example, if irrigation conversion is a big issue, then we should be modeling for it, if wastewater discharge is a major issue, we need to account for it .”
Nitrogen laden wastewater leaching into groundwater is not a new issue, said Abel, pointing to so-called “ghost farms” in the Waikato, where wastewater is irrigated onto farmland, sometimes over decades.
He said other sources related to intensified dairying – such as livestock production and fertiliser – will be contributing to the raised levels and neither Greenpeace nor the Otago researchers were definitively identifying factory discharge as the cause or contributor to the increased nitrates.
“I want to be very clear, it is yet to be understood the part of the dairy factory may be playing, we’re not saying it’s categorically the factory.”
However, the industry is having a dire impact, “sending the water in the Canterbury region on a trajectory to being undrinkable,” he said.
Abel said their work is “not about vilifying individual farmers, it’s definitely a system problem.”
“Access to safe drinking water is a basic human right, and it’s the responsibility of regional authorities to protect that, it’s a fundamental part of their job.”
He said evidence in emerging nitrate science showed health impacts at lower concentrations which raised questions given residents may not know about elevated levels that did not breach the MAV.
What is the baseline level now of nitrate right now? And how long has it been climbing, because it may have been above those levels linked to health impacts for some time before it has finally exceeded the 11.3 milligrams and gone over the drinking water standard?”
“The fundamental problem we’ve got, and this is where the supposed Waimate District Council solution which is this denitrification plan, is that the whole groundwater system across Canterbury is getting worsening nitrate.”
A recent ECan analysis of long-term trends for Canterbury’s groundwater found nitrate levels were still increasing in 75% of bores tested, and improving in 12%.
ECan analysis of a 22-year data set for surface water saw 63% of all sites showing an increasing trend in nitrate.
Water testing is available 10am-4pm on Tuesday at Glenavy Hall, Innes St, and from 9am-midday on Wednesday at Waimate Highland Pipe Band Hall, 33 Paul Street. The public meeting with Chambers is 7pm Tuesday at the Glenavy Hall.