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Authored by Gren Christie of Wise Water Use
First of all, it’s a big problem.
Many of our more shallow bores have high levels of the stuff, way over the supposed safety level set in regulation, as reported by Radio NZ's Anusha Bradley here. The report cites Ngāti Kahungunu spokesperson Ngaio Tiuka:
"Ngāti Kahungunu environment and natural resources director Ngaio Tiuka says the iwi was privy to data that showed nitrate levels are, in some places, even higher than what's in the report.
He said nitrate management had not been a priority for the regional council and needs to be addressed as soon as possible." -
If it’s a problem in shallow bores, it is going to keep on heading down deeper into our aquifer and rivers. Here in CHB our aquifers and rivers are closely connected and our rivers are near tipping point. Nitrate leaching and reduced river flows from over-allocation of water to intensive dairy farms, combined with summer heat, are the prime reason that too many times over summer our rivers are unsafe for people or dogs to swim in - as well as harming the biodiversity and ecology of the river. This is because plant nutrients (fertilisers) such as nitrogen, mix with warm water and stimulate toxic algae growth.
The algae looks like this:
The Hawke's Bay Regional Council (HBRC) gives out warnings about the algae, but only if they know it’s about. We have to pick up the message to be safe.
This is what Stuff reporter Virginia Fallon reported in 2018 with the headline “More Deadly Than Cobra Venom And Delicious To Your Dog”. The article also cites Greater Wellington Regional Council water scientist Mark Heath:
Heath, the council's freshwater scientist, is disappointed that despite the warnings, at least two dogs have already died after eating the algae. Nationwide, about 150 dogs have been killed in the past 15 years, he said.
It's an agonising death and, although he said it was unlikely, he feared what would happen to a child who "got some on their hands" or ate some of the algae.
"This scares me just about every night when we have big algal blooms."
We too have had dog deaths in our Tukituki River. As reported by Radio New Zealand here.
Local dog, Zeffer, in the Tukituki River:
Nitrogen is also being seen more and more as a health risk in drinking water.
This is discussed at length in Otago University Article: Nitrate in drinking water could cause up to 100 cases of bowel cancer in NZ. That's every year, and could lead to 40 deaths.
The biggest contributors are intensive dairy farms. In CHB we have 6 large intensive farms - if you have a lot of cows two of the things used are a) massive amounts of water and b) nitrogen to make the grass grow.
More cows also means more pollution from their urine, another source of nitrates, which then leaches into our waterways.
Unlike phosphate, nitrogen is soluble so riparian planting does little to stop it, as discussed by Stuff reporter Pat Deavoll: Riparian planting does not counter nitrate runoff says environmentalist author
For more on this subject read this information posted on NZ health professional website NZ Doctor which talks about how synthetic nitrogen fertilizer is linked to adverse birth outcomes: NZDoctor.co.nz
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