A warning for paralytic shellfish poisoning was put in place on the 13th of August 2025. Paralytic shellfish toxins have been detected in shellfish at levels over the safe limit set by New Zealand Food Safety. The warning extends from Whakatane to Mount Maunganui.
Nature loves to recycle everything, including waste. In fact our waste contains valuable plant and soil nutrients which first feed the soil biome, and then eventually make their way back up the food chain to be re-consumed as food for humans, and for all of the other plants, critters and organisms that share our environment.
Probably the best way for the environment to recycle human waste, would be for everyone to take their bucket out into the garden every morning and bury it at a shallow depth. Nature will very rapidly convert it into food for the soil. Within hours or days it will have disappeared. That way we are building up local soil fertility. As any good farmer or horticulturalist will tell you, it is all about the soil. Healthy soil means healthy plants. Healthy plants mean healthy nutritious food for us and all the critters. This is the one case I know where garbage in means good stuff out, breaking that general rule (GIGO).
Of course that is not practicable for most people. The next best option is probably earth toilets, but again not so practicable for most people.
New Zealand used to have a widely used, and reasonable compromise, the septic tank. Nothing is perfect, but the septic tank provided a small localised way to treat our waste. The waste broke down in the septic tank, and the soluble nutrients passed out into the local soil. Simple but effective. And there was many a happy orange or lemon tree close by, that grew for years and years without much attention. The septic tank did need to be cleaned out from time to time.
Most fruit trees are optimised to feed on animal waste. The fruit attracts the animals to feed. Most fruits are laxatives which encourage the animals to leave a gold coin donation. And of course, the fruit contains seeds which are spread around by the animals. A very clever recycling system. The fruit trees were very happy to be planted close to the septic tank which was a good substitute for animals, and worked all year round.
In the meantime New Zealand has widely adopted centralised wastewater processing systems. We collect it, treat it, and then dump it into the environment. Bad. Very bad.
Perhaps it is useful to look back and ask why. London is a good example. Early cities used to collect the waste manually and sell it to the farmers. To the farmers it was valuable fertiliser and they were very happy to pay for it. The towns and cities used to have “night carts” to do the job. In large cities that broke down, and waste was often just thrown out onto the street. Ughhhhhh.
Things came to a head in London when it was discovered that human waste was infecting the local wells used for water supply, resulting in fatal deaths from cholera and other diseases. The result, treated municipal water supplies into London, and sort of treated waste out of London into the Thames river. That solved one problem, but of course it created other problems like pollution.
So the main principle is to separate our drinking water supply from our waste water. Interestingly, this simple principle has improved human health and longevity more than all of the medical advances. So rule number one: keep drinking water separate from waste water. We were already doing that in New Zealand, so why did we move to waste water treatment?
Probably the main reason is building density. Septic tanks need an area of land around each building, like the much beloved and virtually extinct quarter acre section. Septic tanks are not very suitable for high density housing, hotels, commercial properties, industry, shops, and offices etc. So those properties need waste water processing of some kind. But that is expensive, so why don’t we share the love, and get the whole community to pay for it.
Tauranga has waste water treatment, and now the central government seems determined to force communities all around New Zealand to adopt waste water treatment. Bad idea. Bad for the environment. Bad for the ratepayer. Bad for our lemon trees. Most back garden lemon trees around Tauranga have died from malnutrition since the septic tanks were removed. It is a worldwide environmental catastrophe.
All of Tauranga’s wastewater winds up at the Te Maunga treatment plant. It is treated, and then dumped out into the ocean via a pipeline. You can see the pipeline easement at the back of Sunrise Ave, and beside the Pacific Coast and Pacific Lakes retirement villages. At one time you could pinpoint the end of the pipeline on google maps, by the large brown stain in the water. You can’t see the stain on the latest google maps. The pipeline is buried under the sand and ends several hundred meters offshore. The large pipes you see on the beach are storm water.
The waste water is treated, but we are dumping a huge nutrient load into the ocean. That is a loss of nutrients from the soil. None of that nutrient will be recycled into the local soil. It is also a huge nutrient load onto the natural environment. Nature loves nutrients. That is a massive amount of food for microorganisms in the ocean, and there is no control over what will grow as a result. You can expect an explosion of good and bad bacteria, and algae etc. One of the main feeders on those organisms are shellfish.
We don’t like to point fingers, but the most likely cause of the shellfish toxin is the “treated” wastewater. The wastewater has probably caused a population explosion of toxic algae, and the shellfish have filtered the algae with the toxin from the seawater. If you eat the shellfish, you are also eating the toxin.
As an aside, does anyone remember the toxic shellfish problem on the North Auckland East Coast Bays some years ago. It killed a number of dogs, but fortunately no humans. Purely a coincidence of course, the problem was clustered around the bays close to the outfall of the Rosedale wastewater treatment plant (lake puipui as it is called by the locals).
I remember one enterprising Auckland City Councillor at the time claiming that the problem was caused by dairy farmers on the Hauraki plains. This is an interesting mental exercise. Apparently, the dairy waste was washed off the farms, down the Piako river, and managed to travel all the way up the Firth of Thames, round the corner to the west past Maraetai and Howick, turned the corner north past Devonport and Takapuna, and lodged itself on the East Coast Bays (approximately 100 km). It managed to do this without creating any toxic shellfish problems anywhere along the way. Amazing. Absolutely amazing. Those dairy farmers are just so cunning and devious, and as a world first, they managed to train their algae to not cause any problems until they had arrived at the East Coast Bays. New Zealand should be capitalising on that know how. Extraordinary.
