Council pans 'dirtiest river' claim
BY JILL GALLOWAY AND LAURA JACKSON
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Horizons Regional Council is rejecting claims the Manawatu River is one of the most polluted in the Western world.
But the scientist who authored a report that ranked the river as one of the worst out of 300 tested is standing by the findings.
Despite some "uncertainties" surrounding the raw data on which the report was based, Dr Roger Young from the Cawthron Institute in Nelson was confident the final analysis was correct.
Horizons chief executive Michael McCartney said it was worrying that the public seemed to accept from media reports, the accuracy of the institute's findings, which he questioned.
The results of testing at Hopelands, near Woodville, topped pollution measurements of 300 rivers and streams across North America, Europe, Australia and New Zealand.
The river was tested using a new method, which measures the amount of dissolved oxygen in waterways every 15 minutes.
Previously testing was done once or twice daily during daylight hours. All 300 rivers included in the report were tested using the same method.
But Mr McCartney said only a few regional councils and research institutes in New Zealand used that method and there was no indication of which other rivers had been tested.
"How many rivers that go through cities can you go down to the end of a street and swim in? You can in Palmerston North.
"You wouldn't do it in Brisbane, or many other cities. When Manawatu River levels were low, and the river clear, 98 per cent of it was fit for swimming."
Mr McCartney said when the river was higher and cloudy, it was usually through a wet period and people were not swimming.
He said people needed to know the river had been cleaned up since the 1980s, when outflows from meatworks, untreated sewage and dairy farm effluent emptied straight out in to the river.
"There was a major campaign to clean up point discharges from 1993 to 2000. Local councils, industries and farmers spent millions of dollars. And the river pollution from those sources, peaked in 2000 and has improved since."
There are not the sudden fish kills due to low oxygen levels now, which were part of the Manawatu River ecology a few years ago, Mr McCartney said.
The river had been trending in the right direction and was certainly not one of the world's worst, he said.
"We have to find the balance the community wants, between economic activity and the environment. It is not what Horizons wants, but what the community thinks is right."
Mr McCartney said it was not helpful to blame one sector for river pollution – farming.
"There has been a shift in farmer mentality. Most want to do the right thing for the land and river."
Dr Young hoped the one point people took away from the report was that the river was very unhealthy.
"It's not important if it is ranked first or third worst in the world, it is very unhealthy."
IS IT REALLY THAT BAD?
The Cawthron Institute research shows the Manawatu River has very high levels of dissolved oxygen, which indicates a poor ecosystem and difficult living conditions for fish, insects and other river life.
Previously, dissolved oxygen levels of the river have been checked during the day, once or twice daily.
The problem with this is that when the sun is up plants in the river produce oxygen, and at night the plants breathe, sucking the oxygen back out.
This means at dawn oxygen levels would be at their lowest.
Under the new testing, dissolved oxygen levels are measured continuously, every 15 minutes, by a sensor.
Jon Roygard said there were drawbacks to not being with the equipment every day, though.
"Before we would take out our equipment, calibrate it on the day, put the probe in, and know we were getting good solid data.
"The difficulty with continuous dissolved oxygen monitoring is that you're not there every five minutes to calibrate the information and so we are still learning about how to do that measurement and ensure calibration stays in place so the record we're collecting is entirely accurate".
It is important the testing works so they can understand what is going on in the river at night, he said. "In the middle of the night there will be troughs that would affect fish and invertebrates."
The readings so far have indicated the river has an extremely unhealthy ecosystem.
"But we haven't had fish kills in the Manawatu for a long, long time," Dr Roygard said.
"We stand by the work scientist Roger Young has done but it is heavily reliant on the accuracy of the raw data and we have some question marks around that."
Other tests Horizons uses to check the river's health include looking at physical factors, such as water clarity, and chemical factors, such as nitrate levels.
"We got good at measuring flow, water temperature and nitrate and now we're going here's a neat different way of measuring water quality that we're investigating," Dr Roygard said. "We're learning, it's science but I think it's the research end of science."
HAVE YOUR SAY
An update on the Cawthron Institute report and Manawatu River assessment will be discussed at Horizons Regional Council's meeting at 10am on Tuesday in the council's Tararua Room.
Horizons is also planning a public debate for all sectors of the community, including farmers, industry, environmentalists and ecologists, to put forward their case on what should be done about the state of the river.
- © Fairfax NZ News
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I live near the Mangatoro river, as far as i see it polluted with trees which have fallen in. Its polluted with Willows which have been plated intentionally by a government department. When asked to help, Horizon was casual to say the least. Mentioning it was not really their problem. So if this is not really their problem to clear rivers. Why do we pay them rates at all? If they are not responsible for our rivers why do they exist? Still looking out over a river with lots of trees in it and willows growing increasingly for many years with no work being done.
We in the Horowhenua demand clean water for recreation, including swimming, fishing, and tourism. One day we may all need this river for our drinking water. Environmental values have been focussed on the main rivers and wetlands and there seems to be little understanding of the values for our small streams and tributaries and the pollution that enters into them. It is time Horizons took a stance, especially when they say in their proposed One Plan that “We’re not going to tolerate poor water quality any longer”. I say put your money where your mouth is, and start prosecuting all businesses and Councils that foul any waterway. As you say “Our children will never forgive us if we don’t look after this precious resource!”
Health impacts of contaminated recreational water There are a number of disease-causing bugs (called pathogens) that once discharged into the marine and freshwater environments can survive for some time. Every time we come into contact with waters that have been contaminated with human and animal faeces, we expose ourselves to these bugs and risk getting sick. Pristine waters are unlikely to present a health risk from these pathogens.How bad is it?When monitoring water quality at New Zealand beaches and rivers, water managers and scientists are interested in the number of disease-causing pathogens present. It is impractical to measure the pathogens directly, so indicator bacteria are used to alert water managers to possible health risks presented by the pathogens.What are indicator bacteria?In the case of the recreational water quality guidelines, the indicator bacteria are enterococci for marine waters and E. coli for freshwaters. These bacteria occur naturally in the gut of humans and animals, including mammals, birds, fish and reptiles. The indicator bacteria themselves do not pose a significant risk to human health. Rather, they indicate the presence of faecal material, which contains disease-causing pathogens. It is the number of enterococci or E. coli per 100 ml of water that is measured and on which the guideline levels are based.What are pathogens?Pathogens are microscopic organisms that cause disease in humans and animals, there are many different kinds. Some of the more widely known are Campylobacter, Salmonella, Giardia, Cryptosporidium and viruses that cause diarrohoea and cold and flu-like symptoms. These pathogens are present in faeces and may enter our waterways through untreated sewage discharges, and from leaky sewerage pipes, septic tanks, stormwater and rural run-off.What does ‘risk’ mean?The risk is of getting sick when swimming, surfing or otherwise being exposed to freshwater or seawater. The guidelines that are used are based on fixed levels of risk, which in turn are based on overseas guidelines (which have been confirmed by New Zealand studies). Overseas investigations have settled on a maximum acceptable level of risk for marine waters of 19 in every 1000 bathers contracting an illness. For freshwaters the accepted level of risk is 8 in every 1000 bathers contracting an illness.Even when beaches and rivers meet the guidelines there will still be a health risk associated with recreational activities in the sea. Because scientists are not directly measuring the pathogens, it is not possible to say there is zero risk to public health, especially where there are known inputs of human and animal faeces.If tested waters exceed the acceptable level of risk, the public is advised that the area is unsuitable for recreational activities.What does ‘illness’ refer to?Illnesses related to contact with recreational waters were initially thought to be confined to gastrointestinal illness such as salmonellosis. More recently Giardia, Campylobacter and Cryptosporidium have also been shown to cause gastrointestinal illness. These pathogens cause diarrhoea and sometimes vomiting associated with ‘tummy bug’ symptoms. Recent studies indicate that respiratory illnesses, such as those that cause cold and flu-like symptoms, can also result from swimming in sewage-contaminated water. Skin, eye and ear infections can also be caught through contact with marine and fresh waters.Illnesses related to toxic substances – such as heavy metals or PCBs – are not measurable with indicator bacteria and are not covered in this fact sheet.
One of the major problemswith this issue, is the denial about how serious it is. Kate McARthur a Regional scientist in her discussion on water quality in the One Plan, states that the Manawatu River is in a very poor condition in comparison to other rivers in NZ. Whether the experts are bamboozling us with results from oxygen levels, nitorgen levels, inverterbrate levels, guess what things aren't looking good. No-one has done any heavy metal testing for the river and published the results in the media, and Horizons etc hope no-one ever does. Althought there has been some improvements in resource consents restricting heavy metals from NZ Pharmaceuticals, PNCC sewage etc, there are still big issues from the Awapuni landfill leachate, and other industry and business that need to be dealt with. The message to Horizons is: Do it now, and stop just talking about it. The One Plan has taken 5 years to get to appeal stage and is still not finalised! It is a plan for 10 years, this is surely evidence of the bureaucrats going crazy in this region.
How fatuous of Mr McCartney, so Palmerstonians can go down to the river and swim, what about those downstream below the city sewerage outfall, Fonterra, NZ Pharmaceuticals can they also go down for a swim with the same confidence?????? The Manawatu is not only a disgrace to the Regional and Local councils but the inhabitants of the district that allow this situation to occur.
Did they measure bacterial contamination levels? Fish life? Insect life etc? Stand on the Fitzherbet bridge on a clam day in sumer and you can count at least 20 trout feeding downstream and another 20 upstream. It seems hard to believe the sensationalist claims that the Manawatu river is the most polluted in the world! Surely measuring just the dissolved oxygen level is poor science?
Living in the area, I not aware of major problems for fish life.
The Dannevirke township that point diposes wastewater into a tributory of the Manawatu has had pond effluent treatment, limited nutrient stripping and advanced microfiltration (filters viruses and bacteria) since 2004. The microfiltration is sufficiently good to potentially allow re-use of the water.
However the testing needs to studied to establish what is going on if it does not agree with other observations. Peter
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I note that the measurements were taken at Hopelands, well upstream of the Woodville side of the Manawatu gorge. I'm not sure how that site represents the entire river, and its poor results may be related to farming or Oringi meatworks or even Dannevirke sewage? I wonder about the quality of the data and the appropriateness of the sampling site too - it doesn't ring true for the clarity of the river and the quality of aquatic life seen in that area.
I think the best indication of the pollution levels would be downstream of Palmerston North and Shannon where the river obviously becomes dirty and has received most of its pollution inputs from everywhere including all of its main tributaries. The tidal part of the river needs to be downstream of the sampling site to avoid the influence of seawater etc. Even at this point, I would have thought the Manawatu was still much cleaner than most rivers in the western world when measured at similar locations just upstream of their tidal estuaries.
I thought the original report from Cawthron only just placed the Manawatu River into the worst 300 rivers in the world, which is not really as worrying as the media reports would indicate either!