Guy Trafford reviews the latest claims on Canterbury water quality by Fish & Game and finds misrepresented sources, misquoted facts, and no transparency around samples selected. Fish & Game respond

Also see the rebuttal at the foot of this article.

By Guy Trafford

Despite a large cross-over of fishers being farmers and vice versa, the relationship between Fish & Game and farming, particularly dairy farming has not been a happy one.

It was Fish & Game who were the first to tag dairy farmers with the label “dirty dairying” and began the national pastime of putting dairy farming under scrutiny at seemingly the expense of anything else. Much of the facts they roll out are correct; what seems to be lacking is a sense of balance and providing credit to those who are leading the way to improved environmental management. Yes, there is a problem and yes dairy farming (among others) have largely contributed to it. But just remember, water quality as an issue has only surfaced in the last twenty five years, at least in Canterbury anyway, and the focus has gone on to it in more detail in about the last fifteen. So given the size and relative importance of agriculture to the economy it is not surprising that it is taking time to turn the ship around.

The latest article to come out of Fish & Game is yet another piece that appears to lack any balance and makes implications that, at least by ECan’s data, appear to be wrong. The article reeks of scaremongering despite the Fish & Game chief executive declaring that it’s not.

It states that Canterbury water nitrate levels are increasing and are predicted to get worse.

Reading the 2016 Ecan report it alludes to, it says no such thing. It does say that, at 2016, 23% of wells surveyed had increased their nitrate levels, over the previous 10 years. 10% had decreased and 67% had remained the same. It did not predict future trends. In fact  (2018) ECan’s latest’s report states “All but one water quality attribute showed more Canterbury sites were improving than degrading over the past 10 years (with a probability of 67% or greater)” and the one that didn’t show improvement was turbidity.

The heading of the article is “Canterbury water testing raises health concerns”.

The supposed driver for the Fish & Game concerns is a Danish report which has found that colon cancer can increase by 15% when exposed to drinking water with nitrate levels over 9.7mg per litre of water when compared to those with access to water with a 1.3mg per litre of water. Fish & Game then go onto say that they worked with Dr Mike Joy to conduct a survey and he found over half had nitrate levels of 3.7mls per litre, nothing like the 9.7 in the Danish study, although to be fair the study did say that over 4mg per litre the potential for increased colon cancer did exist, but no figure was given.

Fish & Game state “One of the world’s largest ever studies on the impacts of nitrates in drinking water in Denmark confirmed that nitrate levels above 3.87 mg/1000ml substantially increases the risk of colorectal cancer (CRC).” I would be happy to be corrected but I could find no such reference.

What the study does state is that “We found statistically significant increased risks at drinking water levels above 3.87 mg/L, well below the current drinking water standard of 50 mg/”. To a researcher, and Dr Joy would be well aware of this, “statistically significant” means that it is unlikely to be a random result but the value is likely to be less than 5% certainly not “substantially increases”.

When it comes to the impact upon trout, obviously anything other than high quality water is less than desirable. However nitrate toxicity for trout is exceedingly low; arguably of more concern is the impact upon our native species which according to a 2014 NIWA study are more vulnerable and trout have also had a fair bit to do with their state.

It is also a pity that there was not more detail about where the water samples came from as the article says they came from across the Canterbury Plains from samples provided by concerned Cantabrians “and from sampling of public water supplies at sports grounds and public facilities”. I would feel more comfortable if the samples came from an unbiased group and knew more about the various sources.

From what I can glean and certainly compared to international standards Cantabrians should feel more reassured about their water quality rather being increasingly concerned.

My intention is not to try and pretend there is not a problem and water quality certainly does need to improve especially when it gets into the rivers. But some balance needs to be brought to the discussion rather than try to create a beat-up for another agenda and to say that the article wasn’t a “scare mongering”… come-on.

As if to prove a point that there is a substantial movement to improve the environmental footprint on most dairy farms, Matamata dairy farmer Tracy Brown won the sustainability Superstar Award at the Sustainable Business Network Awards. Selected from across all businesses, not just agriculture. The award was for Brown’s activity in promoting the sustainability cause and she is a founding member of the Piako Catchment Forum and Mangapapa Catchment Care Group. She and husband Wynn's farm 'Tiroroa' is an environmental award-winning property and they frequently hosts groups to explain what dairy is doing to be more sustainable. The supreme winner was the City Rail Link project in Auckland just to show the diversity of the contestants.

Dairy prices

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The following rebuttal has been received from Fish & Game:

Re. The recent article titled “Guy Trafford reviews the latest claims on Canterbury water quality by Fish & Game and finds misrepresented sources, misquoted facts, and no transparency around samples selected”

In the article Guy said: “Fish & Game state One of the world’s largest ever studies on the impacts of nitrates in drinking water in Denmark confirmed that nitrate levels above 3.87 mg/1000ml substantially increases the risk of colorectal cancer (CRC).” I would be happy to be corrected but I could find no such reference.

I’m not sure why Guy had trouble finding 3.87 as it in the abstract, here is the line from the abstract of the paper “We found statistically significant increased risks at drinking water levels above 3.87 mg/L, well below the current drinking water standard of 50 mg/L.”

Where Guy has gone wrong is that he doesn’t realise the difference between the scales for nitrate (NO3-) which is used in the Danish study and Nitrate Nitrogen NO3-N as used in our study and used in the figures he quotes from Environment Canterbury (ECAN) reports and is the usual nitrogen species used in New Zealand. They are both measuring the same thing but on a different scale because of molecular weights (see table below).

What this means is that the 50 mg/l drinking water standard quoted from the Danish paper is identical to our New Zealand and Word Health Organisation limit for human health of 11.3 mg/l nitrate nitrogen (50 multiplied by 0.22 = 11.3 using the table below).

Thus, the 3.87 mg/l that is the trigger value for increase in the chance of cancer in the abstract of the Danish paper is in New Zealand parlance 0.87 mg/l NO3-N. This means that around 90% of the samples we gathered in Canterbury exceeded that number.

Further in response to Guys implication that our sample was biased; the latest report from ECAN shows that half of the wells they monitor have values greater than 3mg/l NO3-N (three times or more higher than the Danish cancer number) so our numbers fit well with their survey, they don’t break down the less than three so can be more accurate.

Conversion between nitrate (NO3) and nitrate-nitrogen (NO3-N):

Interconverting Nitrate as Nitrate (Nitrate-NO3) and Nitrate as Nitrogen (Nitrate-N) The atomic weight of nitrogen is 14.0067 and the molar mass of nitrate anion (NO3 - ) is 62.0049 g/mole.

Therefore, to convert Nitrate-NO3 (mg/L) to Nitrate-N (mg/L):

Nitrate-N (mg/L) = 0.2259 x Nitrate-NO3 (mg/L) And to convert Nitrate-N (mg/L) to Nitrate-NO3 (mg/L): Nitrate-NO3 (mg/L) = 4.4268 x Nitrate-N (mg/L)


Guy Trafford responds:

It appears that my lack of in-depth chemistry knowledge has got me into trouble and it appears that the data as used by the Fish & Game article does pose reason for concern.

I know this as I received a rather detailed response from both Mike Joy and the Fish & Game CEO Martin Taylor.  This highlighted a couple of things to me. One was that I have a bit to learn around the various types of nitrates and on this count got it wrong (see below). So guilty as charged over that error in interpretation: “Where Guy has gone wrong is that he doesn’t realise the difference between the scales for nitrate (NO3-) which is used in the Danish study and Nitrate Nitrogen NO3-N as used in our study and used in the figures he quotes from Environment Canterbury (ECAN) reports and is the usual nitrogen species used in New Zealand. They are both measuring the same thing but on a different scale because of molecular weights (see table below). “

It was perhaps unfortunate that more clarity over the use of a different basis of measurement was not included in the article if better appreciation of the sampling was the aim. One of the principles impressed upon me as a student was to always consider the audience and while I will admit to deficiencies around chemistry (and many other things). I don’t consider myself hugely out of step with plenty of others and if my interpretation was flawed (and it was) then perhaps I wasn’t the only one. So, on that point I accept; an apology is in order and given.

However, I still stand by what I said about a lack of balance and a misuse of information in the broader picture.

Every-one knows that agriculture and particularly dairying have a negative impact upon the environment and I am not a huge fan of it. But I also am aware that large strides have been taken both in actions and attitudes and plenty of work is being continued to be done to try and mitigate impacts further.

Farming families have invested immense amounts of sweat and tears as will as capital and are not going to disappear so working with the industry and recognising gains made may be a more productive way forward.

A difficulty farming faces is that food retailers (supermarkets) are committed to providing consumers with the cheapest food available and the consumer welcomes this. This attitude runs at odds with the consumer then wondering why we have this move to corporate farming with many of the negative attributes that go with it. They want it both ways but fail to see what and where the cost is.

I find it ironic that this conversation is being had with Fish & Game which after agriculture are probably one of the sectors which have had negative impacts upon native water species.  It appears Government is also viewing the impact of trout in less than favourable eyes as a bill is before Parliament to aid in the protection of native fish species. Quoting the F&G site “The Indigenous Freshwater Fish Amendment Bill aims to provide better protection for indigenous fish such as galaxids, whitebait, eels, bullies, torrent fish, mudfish and other species. But the Bill also poses a serious threat to trout and angling. It allows trout and salmon to be removed from particular rivers and lakes, even if they are significant trout and salmon fisheries.” Needless to add Fish & Game view this bill as threatening and are encouraging members to contest it. So perhaps farming and Fish & Game do have some things in common.

We welcome your help to improve our coverage of this issue. Any examples or experiences to relate? Any links to other news, data or research to shed more light on this? Any insight or views on what might happen next or what should happen next? Any errors to correct?

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13 Comments

As soon as I saw Mike Joy was involved, I mentally discounted the entire thing. It's the usual fear-mongering we have seen in most popularisations of quasi-scientific 'investigations'. It carries about as much scientific weight as the carefully staged 'rescues' of everything from chickens to pigs, probably filmed on a sound stage in Nevada for all the provenance given.

The unfortunate thing is that it tends to reduce the trust in science as a whole, and that is definitely not a Good Thang.

As soon as I saw Mike Joy was involved, I mentally discounted the entire thing.

Really? He's got an amazing portfolio of published academic work;

Book chapters
Joy, M.K., Foote K.J. (2017). Damn the dams. In N. Legat (Ed.), The journal of urgent writing (Vol. 2, pp. 236-252). Palmerston North: Massey University Press. Retrieved from http://www.masseypress.ac.nz/
Joy, M. K. (2017). Our deadly nitrogen addiction. In C. Massey (Ed.), The New Zealand Land & Food Annual (Vol. 2, pp. 119-130). Palmerston North, New Zealand: Massey University Press. Retrieved from http://www.masseypress.ac.nz/books/the-new-zealand-land-food-annual-2017/
Joy, M. K. (2016). The making of a river radical. In N. Legat (Ed.), The journal of urgent writing (Vol. 1). Palmerston North: Massey University Press. Retrieved from http://www.masseypress.ac.nz/
Joy, M. K. (2014). Freshwaters in New Zealand. In A. Stow, N. Maclean, & G. Holwell (Eds.), Austral Ark: The State of Wildlife in Australia and New Zealand (pp. 227-239). Singapore: Cambridge University Press. Retrieved from http://www.cambridge.org/nz/academic/subjects/life-sciences/ecology-and-...
Joy, M. K. (2014). Cool, clear water. In D. Cooke, C. Hill, P. Baskett, & R. Irwin (Eds.), Beyond the Free Market; Rebuilding a Just Society in New Zealand. Auckland, New Zealand: Dunmore Press. Retrieved from http://www.dunmore.co.nz/products/828354-BeyondtheFreeMarketRebuildingaj...
Joy, M. K., & Death, R. G. (2013). Freshwater Biodiversity. In J. R. Dymond (Ed.), Ecosystem Services In New Zealand (pp. 448-459). Lincoln New Zealand: Manaaki Whenua Press. https://www.landcareresearch.co.nz/publications/books/ecosystem-services...
Joy, M. K. (2011). Watering down the image. In L. Johnsen, & T. Ward (Eds.), Organic Explorer New Zealand (3rd Edition ed., pp. 48-51). New Zealand. Retrieved from http://www.organicexplorer.com/

Refereed journal articles

Piria, M., Simonović, P., Kalogianni, E., Vardakas, L., Koutsikos, N., Zanella, D., . . . Joy, M. K. (2018). Alien freshwater fish species in the Balkans—Vectors and pathways of introduction. Fish and Fisheries, 19(1), 138-169. doi:10.1111/faf.12242
Weeks, E. S., Death, R. G., Foote, K., Anderson-Lederer, R., Joy, M. K., & Boyce, P. (2016). Conservation Science Statement. The demise of New Zealand's freshwater flora and fauna: A forgotten treasure. Pacific Conservation Biology, 22(2), 110-115. doi:10.1071/PC15038
Joy, M. K. (2015). Water quality issues in New Zealand - monitoring methodology and approaches to improving quality. The Journal of the New Zealand Institute of Primary Industry Management, 20(3), 32-36. Retrieved from https://www.nzipim.co.nz/Folder?Action=View%20File&Folder_id=120&File=Jo...
Joy, M. K. (2015). Water quality issues in New Zealand - stressed ecosystems and future solutions. The Journal of the New Zealand Institute of Primary Industry Management, 19(2), 22-27.
Foote, K., Joy, M., & Death. (2015). New Zealand dairy farming: Milking our environment for all its worth. Environmental Management, 56(3), 709-720. doi:10.1007/s00267-015-0517-x
Foote, K. J., Joy, M. K., & Death, R. G. (2015). New Zealand Dairy Farming: Milking Our Environment for All Its Worth. Environmental Management, 56(3), 709-720. doi:10.1007/s00267-015-0517-x
Death, R. G., Death, F., Stubbington, R., Joy, M. K., & van den Belt, M. J. (2015). How good are Bayesian belief networks for environmental management? A test with data from an agricultural river catchment. Freshwater Biology. doi:10.1111/fwb.12655
Weeks, E., Kingsford, R. T., Taylor, A., & Joy, M. K. (2014). Protecting the future of New Zealand’s freshwater ecosystems. Society for Conservation Biology, 1(1), 1-10.
Joy, M. K. (2014). New Zealand’s freshwater disaster. New Zealand Science Review, 71(4), 97-104.
McEwan, A. J., & Joy, M. K. (2014). Habitat use of redfin bullies (Gobiomorphus huttoni) in a small upland stream in Manawatu, New Zealand. Environmental Biology of Fishes, 97(2), 121-132. doi:10.1007/s10641-013-0131-9
Makan, T., Castro, I., Robertson, A. W., Joy, M. K., & Low, M. (2014). Habitat complexity and management intensity positively influence fledging success in
the endangered hihi (Notiomystis cincta). New Zealand Journal of Ecology, 38(1), 53-63. Retrieved from http://newzealandecology.org/nzje/3104
McEwan, A. J., & Joy, M. K. (2014). Diel habitat use of two sympatric galaxiid fishes (Galaxias brevipinnis and G. postvectis) at two spatial scales in a small upland stream in Manawatu, New Zealand. Environmental Biology of Fishes, 97(8), 897-907. doi:10.1007/s10641-013-0191-x
McEwan, A. J., & Joy, M. K. (2013). Responses of three PIT-Tagged native fish species to floods in a small, upland stream in New Zealand. New Zealand Journal of Marine and Freshwater Research, 47(2), 225-234. doi:10.1080/00288330.2013.773918
McEwan, A. J., & Joy, M. K. (2013). Habitat use of redfin bullies (Gobiomorphus huttoni) in a small upland stream in Manawatu, New Zealand. Environmental Biology of Fishes, 1-12.
Joy, M. K. (2011). Our sacred cows. Forest and Bird, 134, 19-24. Retrieved from http://www.forestandbird.org.nz/what-we-do/publications/magazine-articles
McEwan, A. J., & Joy, M. K. (2011). Monitoring a New Zealand freshwater fish community using passive integrated transponder (PIT) technology; Lessons learned and recommendations for future use. New Zealand Journal of Marine and Freshwater Research, 45(1), 121-133. doi:10.1080/00288330.2010.541925
Schwendel, A. C., Death, R. G., Fuller, I. C., & Joy, M. K. (2011). Linking disturbance and stream invertebrate communities: How best to measure bed stability. Journal of the North American Benthological Society, 30(1), 11-24. doi:10.1899/09-172.1
Schwendel, A. C., Joy, M. K., Death, R. G., & Fuller, I. C. (2011). A macroinvertebrate index to assess stream-bed stability. Marine and Freshwater Research, 62(1), 30-37. doi:10.1071/MF10137
Joy, M. K., & Salmon, G. (2011). 100% pure? Fish and Game New Zealand, (Special Issue 33), 8-15.

Selected commissioned reports

Joy, M. K. (2017). Chapter 6. Water quality: Porirua Ki Manawatu Inland Waterways Historical report. Wellington: Crown Forest Rental Trust. Retrieved from http://www.cfrt.org.nz/
Joy, M. K. (2017). Chapter 7. Fisheries and wetlands: Porirua Ki Manawatū Inland Waterways Historical Report. Wellington: Te Rangitāwhia Whakatupu Mātauranga Ltd.
Potter, H., Spinks, A., Joy, M.K., Baker, M., Poutama, M., & Hardy, D. J. (2017). Porirua ki Manawatu Inland Waterways - Historical Report: Porirua ki Manawatu Inland Waterways - Historical Report. Wellington, New Zealand: Crown Forestry Rental Trust.
Joy, M. K. (2016). Affidavit of Dr. Michael Kevin Joy in Support of Claimants in the Waitangi Tribunal the National Freshwater and Geothermal Resources Inquiry: Woodward Law.
Joy, M. K., Lowe, M., Ingley, R., & Utech, C. (2016). A Predictive Model of Freshwater Fish Distribution for the Auckland Region – 2016 Update. Prepared by Morphum Environmental and Mike Joy for Auckland Council:
Joy, M. K. (2016). Fish Index of Biotic Integrity (IBI) for Horizons Regional Council. Palmerston North: Horizons Regional Council. Report and associated software.
Joy, M. K. 2013. Freshwater fish predictive modelling for bioassessment; a scoping study into fish bioassessment models in New Zealand; A report to the Ministry for the Environment. Wellington.
Joy, M. K. 2013. A fish index of biotic integrity for the Tasman Nelson District. Massey University.
Joy, M. K., B. O. David, and M. D. Lake. 2013. New Zealand freshwater fish sampling protocols Pt.1: Wadeable River and streams. Field guide. The Ecology Group, Institute of Natural Resources.
Joy, M. K., B. O. David, and M. D. Lake. 2013. New Zealand Freshwater Fish Sampling Protocols: Part 1- Wadeable Rivers and Streams. Massey University, Palmerston North.
Joy, M. K. and N. K. Atkinson. 2012. Salmonids and Native Fish in New Zealand; Are Trout to Blame for the Decline in Native Fish? , A report to Fish and Game New Zealand. Wellington.
Worner, S. P., Takayoshi, I., Leday, G., & Joy, M. K. (2010). Surveillance Tools for Freshwater Invertebrates; MAF Biosecurity Technical Paper: Bio-Protection Research Centre Lincoln University.

Selected conference papers

Joy, M. K. (2017, March 31). The new realities of food production. At the annual Animal Rights Conference AR17. Lower Hutt.
Joy, M. K. (2017, February 14). Looking in – what is the perception of the environmental performance of sheep and beef farms? At the 2017 Beef & Lamb New Zealand Environment Conference.
Joy, M. K. (2016, February 17). Freshwater management on farm. Presentation to Farmwise Consultants Hamilton LIC.
Joy, M. K. (2016, March 21). New Zealand's freshwater future. Presentation to the Christchurch branch of the Royal Society.
Joy, M. K. (2016, November 15). From quiet freshwater scientist to noisy activist; what happens when you get angry? The 2016 Richard Norris Lecture at the University of Canberra. Retrieved from http://www.canberra.edu.au/events/view/15925
Joy, M. K. (2016, October 1). Polluted Inheritance. The annual Wakim Memorial Lecture Pax Christi Aotearoa-New Zealand Auckland.
Joy, M. K. (2015, October 29). Environmental Protection Failure New Zealand a case-study. Invited plenary at the EIANZ Annual Conference. Challenging the Status Quo: Excellence in Environmental Practice. Perth.
Joy, M. K. (2015, August 29). The state of the nation’s water- ecosystem health. ECO New Zealand Annual Conference Dialogues on Fresh Water: navigating impasses and new approaches. Christchurch. Retrieved from http://www.eco.org.nz/about/eco-conference-2015.html
Joy, M. K. (2015, August 17). The importance of true clean green New Zealand to the Tourism industry. Keynote presentation to The Tourism Export Council AGM Dunedin.
Joy, M. K. (2015, August 19). Environmental impacts of Forestry on New Zealand freshwater. In PF Olsen Forestry Contractors, Rotorua.
Joy, MK. (2015, March). State of our awa. Presented at Ngati Kahunugunu annual Fishhook Summit. Napier Sailing Club.
Foote, K., & Joy, MK. (2014, November). Role of the Dairy Industry in New Zealand's ecological decline. Presented at New Zealand Ecological Society Annual Conference. Massey University, Palmerston North, New Zealand.
Foote, K., & Joy, MK. (2014). The True Cost of Milk: Environmental Deterioration vs. Profit in the New Zealand Dairy Industry. New Zealand Agriculture and Research Economics Society. http://ageconsearch.umn.edu/handle/186735: New Zealand Agricultural and Resource Economics Society
Joy, MK. (2014, August). Will the National Objectives Framework protect our freshwater species, and does it matter? Presented at Environmental Defence Society Conference - Navigating Our Future. Auckland, New Zealand.
Joy, MK. (2014, November). New Zealand’s shame: the commercial harvesting of threatened endemic and native fish species. Presented at New Zealand Ecological Society Annual Conference. Massey University, Palmerston North.
Joy, M. K. 2013. Where we are now; freshwater reality (Keynote address). Manawatu River Solutions, Massey University Palmerston North.
Joy, MK. (2013, September). White Gold - Dairy Production in New Zealand. Presented at Black and White Gold, Annual Conference of the Resource Management Law Association. New Plymouth, New Zealand.
Joy, MK. (2013, November). Freshwater crisis in New Zealand. Presented at Strange Baroque Ecologies Symposium. City Gallery, Wellington.
Joy, M. K. 2012. Freshwater Science in New Zealand (Plenary). New Zealand Freshwater Sciences Annual Conference.
Schwendel, A., Joy, M., & Fuller, IC. (2011). A macroinvertebrate index to assess stream bed stability. (pp. 38 - 38). , HydroEco 2011, Hydrology and Ecology: Ecosystems, Groundwater and Surface Water - Pressures and Options
Schwendel, AC., Joy, M., & Fuller, IC. (2011, May). A macroinvertebrate index to assess stream bed stability. Presented at HydroEco 2011, Hydrology and Ecology: Ecosystems, Groundwater and Surface Water - Pressures and Options. Vienna, Austria.
Joy, MK. (2011, March). How do fish like poor water quality? Presented at New Zealand Land Treatment Collective Annual Conference. Palmerston North Convention Centre, New Zealand.
Joy, MK. (2011, June). New Zealand's 100% Pure, Clean Green Myth. Presented at Royal Forest and Bird Annual General Meeting. Mercure Hotel Wellington.
Joy, MK. (2011, August). How pollutant impacts on freshwater ecology and how the "water quality" measures used now just don't measure up ecologically. Presented at The New Zealand Trade and Waste Forum Inaugural Conference. Napier, New Zealand.
Durpoix, D., Joy, M., & Perry, P. (2010, July). Environmental attitudes of New Zealand farmers: The importance of affect and direct contact with nature. Presented at International Symposium on Environmental Sociology and Sustainable Development. Gothenburg, Sweden.
Joy, M. (2010, November). New Zealand's freshwater crisis: The triumph of economists over ecologists. Presented at Biodiversity: 2010 and beyond. University of Otago, New Zealand.

Why would you "discount" his knowledge?

Since I heard him on the Country radio show a couple of years back saying he believed the world needs to become vegan and he seeks media attention to achieve that goal, I have him down as an activist not a scientist.

A seemingly well balanced article Guy.
Sadly for every fake negative news article, it takes five to balance the untruths stated.
It is also unfortunate that rationale and honest debate seems to have been increasingly replaced by wild, and yes, untruthful claims, and given legitimacy by Trump.

Much of the facts they roll out are correct; what seems to be lacking is a sense of balance and providing credit to those who are leading the way to improved environmental management.

Yes, there is a problem and yes dairy farming (among others) have largely contributed to it.

But just remember, water quality as an issue has only surfaced in the last twenty five years, at least in Canterbury anyway, and the focus has gone on to it in more detail in about the last fifteen.

...My intention is not to try and pretend there is not a problem and water quality certainly does need to improve especially when it gets into the rivers.

Fair enough. Sounds like Fish and Game should have done a better job of accurately reporting the work of others. Albeit as noted, yes there's a problem and we need to clean up farming and water.

(Just as we need to increase investment in city infrastructure to do the same.)

Surely the question is...why the heck has fish and game had to do any of this? So nice try, but if it wasn't for Fish and game and other group,s like F&B matters like water quality and conservation wouldn't see the light of day. Your efforts would be better put to supporting these causes, not excusing the mess created.

Short answer - they haven't had to. What we are looking at has zero provenance (those samples could have come from anywhere in NZ, or from the nearest ditch adjacent to a freeedom camping site, or...where?), is being spruiked by a 'scientist' who has a track record of sensational pronouncements, and by a body whose introduced fish and fauna are busily chomping their way to dominance over natives. Hence the discount.

Thye real work is being done, out of the limelight and by hundreds of landowners, zone committees, real scientists and real accountable public authorities.

Guy, correct me if I am wrong.

Have you confused N03 with N03-N?
3.87 Nitrate NO3 as per the cancer paper is equal to 0.81 in nitrate nitrogen N03-N.
I recall 90% of Canterbury water exceeded the 0.81 mg/1 N03-N.

Not a good look for clean green NZ that the water in Canterbury exceeds the colerectal cancer risk is it?

As for the water source...that's a distraction - it's in the water, it's in the environment.

....still waiting.

More to the point one of the problems with Mike Joy's data collecting experiment was that the samples provided data on nitrate-nitrogen levels and the international study looked at nitrate levels. They are two different measures as you point out and comparing the two is not comparing apples with apples and is one of the reasons why Mike Joy is being misleading with his data.

Why do F&G and Mike Joy consistently single out Canterbury? Cancer causes can be many and varied depending on the individual.A national registry-based cohort study in Denmark [32] evaluated average nitrate concentrations in PWS and private wells in relation to colorectal cancer incidence among those whose 35th birthday occurred during 1978–2011.
Because the study did not interview individuals, it could not evaluate individual-level risk factors that might influence endogenous nitrosation.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068531/

When the data is adjusted to remove the effect of varying age structures between regions -- bowel cancer risk increases with age -- South Canterbury and Otago-Southland, remained above average.
https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11666229

https://www.southerndhb.govt.nz/pages/bowel-screening-programme/
https://www.stuff.co.nz/national/health/100508219/canterbury-to-get-bowe...

Your comments don't give weight to anything. The highest nitrate levels are around Ashburton and a few pockets of Selwyn which is in central Canterbury. Otago's levels are not too bad but there are also higher levels in Auckland, Waikato and Southland. Nitrate levels are quite high in some types of cured meats like bacon and salami and NZers eat quite a lot of these products and have been told to cut down as it leads to a somewhat elevated cancer risk, probably significantly more of an issue that groundwater.

Mike Joy is an ecologist. He is not qualified to make statements about health risks nor can he be relied upon to accurately interpret a public health study.