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Water pollution affects New Zealand rivers and lakes. While ecologists push for a lower nitrate level maximum, Ngāi Tahu seek authority over waterways in their tribunal area.
Freshwater degradation puts ecosystems at risk and limits communities’ access to safe, usable water. South Island rivers and lakes are claimed to be beyond degradation but on the verge of extinction. To provide safe water and protect the wellbeing of culture and environment means protecting the health and wellbeing of freshwater.
Water pollution occurs when harmful substances, like chemicals and microorganisms, contaminate a stream, lake, river, or other body of water, degrading water quality and making it toxic for communities.
Known as a universal solvent, water can dissolve more substances than any other liquid. As a result, water is uniquely vulnerable to pollution. Toxic substances from farms, factories and towns easily dissolve into and mix with water, causing water pollution. Water pollution threatens freshwater ecosystems and communities’ ways of life, making water unsafe for use.
Sources of pollutants include sediment, nutrient, heavy metals, and pathogens. Sediment can make the water cloudy (turbid) and smother habitats at the bottom of river and lake banks, degrading ecosystems. Nutrients like nitrogen and phosphorus can reduce rivers and lakes’ cultural and recreational value by leading to algal blooms. Heavy metals, like copper and zinc, can accumulate, making freshwater species unsafe to eat and threatening life.
For example, the clear waters that run through the Mount Aspiring National Park in the South Island ranges are among the purest in the world. As flows run from icy peaks down through rivers to the sea – a process that can take a hundred years.
But as rivers flow through farms and cities, they become some of the most polluted in the developed world. Irrigation schemes and synthetic fertilisers enable poor soil to sustain dairy farming.
15 years from 2002, New Zealand’s irrigated land has doubled and now takes up half of the country’s freshwater supply. A 2020 government report found that Canterbury, Christchurch, accounted for 64% of New Zealand’s irrigated land in 2017.
Regional Irrigated Land Area
(Source: Statistics NZ)
2019 reports show Canterbury as the highest total irrigated land area of the New Zealand regions, with double the hectares compared to 2002.
It’s an unjust situation that we’re leaving such huge astronomical issues – not only with freshwater but with the climate too.
Water pollution affects almost all rivers and some lakes. Concentrations of pollutants in freshwater are higher in farming, forestry and urban areas than in natural conditions.
Pollution is difficult to reverse, as reducing pollution requires a significant investment and dedication to change behaviour.
Freshwater degradation heightens the risks to human health and cultural well-being and practices while also threatening our native species and habitats.
Human health is at risk, cultural well-being is threatened, and primary industry operations can be limited. Poor water quality negatively impacts aquatic life, ecosystems and communities – it’s the heart of New Zealand and is directly connected to a sense of identity.
New Zealand’s freshwater rivers are among the most polluted in the developed world. A 2020 government report found nearly 60% of the country’s rivers carry pollution above acceptable levels, with 95% to 99% of rivers in pastoral, urban and non-native forested areas contaminated.
Ecologists have pushed for a nitrate bottom line of 1 mg/L of nitrate nitrogen, bringing New Zealand in line with the European Union and China.
The 1 mg/L limit is the trigger for eutrophication, where uncontrolled plant and algal growth are caused by excess nutrients, like nitrate, in the water, which can cause oxygen levels to fluctuate and harm fish and aquatic life.
Farmers use nitrogen fertilisers to grow grass on the paddocks, but in the river, it grows algae. Algae photosynthesise, meaning they use oxygen in the night, then they respire, and the oxygen levels drop down to where everything virtually dies. Then, during the afternoon, the levels rise back up and reach dangerous heights. Such fluctuations are truly harmful to river life.
The current national policy statement limit of nitrates is 2.4 milligrams, and often, freshwater is four times that. With the bottom line set at 2.4 mg/L, the New Zealand government claims that the limit would be non-toxic for 95% of species.
Nitrate-nitrogen River Measurements
(Source: Statistics NZ)
Exceedance of the ANZG guidelines’ default values can indicate a degree of human impact and potential risk to aquatic ecosystem health.
Due to degrading ecosystem health, food gathering, such as salmon and trout fishing, is also risked. Low water quality can make such procedures unsustainable and unsafe. Even recreational activities are limited, as water degradation deems various rivers and lakes unsafe for fishing, kayaking, swimming and doing the activities New Zealanders enjoy – it ruins the reputation of the beautiful landscape and pushes away visitors.
There’s another group fighting for the future of New Zealand’s freshwater. Ngāi Tahu, the tribal group, their territory covers the majority of the South Island. The group is taking legal action against the government for fiscal and regulatory authority over freshwater in the area.
Te Mana o te Wai, the vital importance of water, is fundamental for managing freshwater. It is a concept integrated with the health and well-being of our waters, from the mountains to the seas. The waterways are connected to a sense of identity, as we are connected to water and the natural world through whakapapa.
Each waterway has its own mauri, or life force, which creates a deep connection between Māori and the natural environment. Generations have built their way of life around the waterways based on boating and fishing in New Zealand’s unique and pristine aquatic environment.
After decades of degradation of the South Island’s rivers, Ngāi Tahu seeks authority over waterways in their tribal area.
Says Gabrielle Huria, the head of the tribe’s freshwater unit.
The freshwater rivers and lakes of the South Island are beyond degradation but on the verge of extinction. A Ngāi Tahu historian and community leader, Dr Te Maire Tau, has approached the unprecedented high court concerning Māori obligations to the waters.
Ngāi Tahu is seeking recognition of its rangatiratanga (chieftainship) over freshwater ways. While rangatiratanga is difficult to describe in western terms, it effectively means the tribe seeks regulatory control over the waterways.
Dr Tau says.
Within their community, everything stretches back to their ancestors. There is no waterway from which they don’t claim descent; as for Māori, water is an ancestor. As the government, scientists and farmers disagree over river management, Dr Tau says it’s time to let Māori take the lead.
The problem lies in the water quality. If we’re not aware of the changing water quality levels, how can we improve the waters?
The pollution and degradation of our water quality are about the future children and grandchildren. We’re leaving them such huge astronomical issues – not only with freshwater but with the climate too.
Real-time water quality monitoring is a step in the right direction of improving water quality. The five sensor water quality monitor includes IoT connectivity. Paired with data interpretation software and signal mate, it’s suitable for any water environment to benefit the community.
Empowering New Zealanders to understand their ecosystems means being aware of how what we do impacts our waterways and how the degradation of the waterways impacts us. If we commit to water quality monitoring, we have the opportunity to restore our freshwater ecosystems and South Island waterways for the generation to come.
Keep up to date with water quality data, research and compliance. With our real-time water monitor, we provide consistent water quality data translated into easy-to-understand information. Empowering you to protect New Zealand waters with environmental science and helping you understand water health.