7 May 2017

Insight: A Line in the Sand for Freshwater Quality?

From Insight, 8:12 am on 7 May 2017
Pourewa Stream

Pourewa Stream: A tributary of the Rangitikei River, which has a status equivalent to a national park. Photo: RNZ / Hans Weston

The water in the Pourewa Stream near Marton is at a standstill, bubbles are rising to the surface and the first word that comes to mind is stagnation.

The Pourewa is a tributary of the Rangitikei River - one of 15 in the country with a water conservation order on it, giving it a status equivalent to that of a national park.

The director of Palmerston North-based environmental consultancy Catalyst Group, Greg Carlyon, said the purity of the stream was far from what it should be.

"This shouldn't be brown, it should be lovely and crystal clear, you should be able to see through the water from side to side if you're under there with a snorkel."

"When you look at that water it doesn't take a scientist to tell you that it's not in good shape. It's got no clarity, you can see the wee bubbles there, which means it's having trouble kind of circulating and operating as an ecosystem should."

Mr Carlyon described the Pourewa Stream as being like every other little lowland stream in New Zealand: facing a multitude of pressures coming from different sources.

Upstream is the Hunterville township, which feeds its sewage into the water; there were dairy farms along the stream's edge and little vegetation shading it, meaning it was warmer than it should be, he said.

Greg Carlyon, Environmental Consultant

Greg Carlyon: "It doesn't take a scientist to tell you that it's not in good shape." Photo: RNZ/Hans Weston

"We've added so much to this river that is just not really functioning the way that it should."

The problems facing the Pourewa Stream rolled off Mr Carlyon's tongue. Human waste, animal waste, fertiliser, contaminants. The stream is a microcosm of the issues affecting all of the country's waterways to some degree.

A landmark report on New Zealand's freshwater, from the Ministry for the Environment and Statistics New Zealand, was released at the end of last month.

It is the most definitive piece of work from the ministry on the state of the country's fresh water and confirms the serious challenges facing it.

The report will be a benchmark for testing the quality of fresh water in the years ahead, to show whether the country is on the right path when it comes to its quality and health.

There was a strict legislative framework for the report. It was required to illustrate the state of waterways using data, but not to produce policy recommendations.

Nitrogen and phosphorus are the nutrients of most concern to New Zealand.

According to the data in the report, nitrogen levels are getting worse at 55 percent of monitored river sites across New Zealand. However, phosphorus levels are improving.

The rate of agricultural land intensification in New Zealand has been one of the world's highest, with dairy herds growing by 69 percent between 1994 and 2015 to 6.5 million, although sheep numbers fell 41 percent.

Nitrogen leaching from agricultural soils is estimated to have increased 29 percent from 1990 to 2012, due to increased urine and faeces from livestock and fertiliser application.

Antarctic researcher Professor Ian Hawes

Water quality scientist Ian Hawes says he's in no doubt that agriculture intensification is to blame for a good part of the country's water woes. Photo: RNZ / Conan Young

Secretary for the Environment Vicky Robertson said after the report's release that there was not enough conclusive evidence to link the degradation of fresh water with the dairy industry.

Fertiliser and cities

Water quality scientist Ian Hawes, who works at the Waterways Centre for Freshwater Management at the Universities of Canterbury and Waikato, said there has been a dramatic increase in the use of fertiliser in parts of New Zealand.

There was no doubt this has had an impact on nitrate concentration, and opened up possibilities for more intensive livestock farming in lowland areas, he said.

"Which has had an impact on sediment run off, it impacts on E coli runoff as well from these areas. So there's no doubt, I don't think really, that intensification of agriculture has had an accelerating effect on the decline of water."

Urban areas have also played a part in the deterioration of water quality.

Urban land only covers about 1 percent of New Zealand, but 87 percent of people live in urban areas, and the population grew 17 percent between 1996 and 2013.

High concentrations of heavy metals from sources such as vehicle wear (copper from brake pads and zinc from tyres), metal roofing and industrial yards get into streams through stormwater. The report says this can cause the accumulation of sediment, plant and animal tissue to concentrations that are toxic to freshwater life.

Nutrients also get into urban streams through the stormwater system, from spills and fertiliser used on lawns and golf courses.

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Urban areas have also played a part in the deterioration of water quality. Photo: Supplied / NIWA

Fish, invertebrates and plants under threat - and birds

High concentrations of nitrogen and phosphorus can cause excessive plant growth and algal blooms.

The effect of this is that it reduces oxygen levels and prevents light from penetrating the water, which has a negative impact on freshwater plants and animal species. Very high concentrations of nitrogen can be toxic to freshwater life and can make water unsafe for people to drink.

The report highlights the loss of freshwater plants and creatures as a result of these effects.

About 72 percent of native fish, 34 percent of invertebrates and 31 percent of freshwater plants are at risk or threat of extinction.

Gerry Closs heads the University of Otago's Zoology Department. His main research interest is freshwater fish, but he also does work on invertebrates.

Gerry Closs heads the University of Otago's Zoology Department

Professor Gerry Closs specialises in freshwater fish - and he says their populations are suffering. Photo: RNZ/Kate Gudsell

He said losing biodiversity made it more difficult for streams to process pollution, and a new pattern of decline was starting to emerge.

"It's a significant decline, particularly in fish. What is changing too is that some of what were previously considered widespread common species are also starting to show evidence of decline, which is worrying, it suggests sort of a widespread impact on lowland rivers and lakes."

Professor Closs said many of the country's native birds were reliant on invertebrates for food, and there was a loss of life around the whole system, as well as a loss of recreational values such as swimming and fishing.

Cultural health to be measured

For the first time, meanwhile, a cultural health index of freshwater sites has been developed, which measures the factors that are of cultural importance to Māori.

In the past 10 years tangata whenua and hapū groups across the country have determined the health of a number of rivers, lakes and streams.

One of the measurements is the status of mahinga kai, or customary food gathering.

Of the 39 sites assessed, 28 had a poor or very poor mahinga kai status, seven were moderate and the remainder good.

The information collected by iwi will be incorporated into future reports to help build a better picture on the state of freshwater.

The Ministry for the Environment said it also hoped to improve the information it used, because the absence of data has been a problem in trying to illustrate water quality and health.

There has been insufficient data to determine trends for E coli bacteria in the water, sediment - another major problem - and activities which influence water flow such as irrigation.

The next report focusing just on freshwater will be released by the ministry in 2020.

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Who is really kidding themselves in the debate surrounding our rivers and lakes? The public, the farmers or the government? Look back at RNZ series Water Fools? about the diverse threats facing waterways in different regions here.