Ōtūwharekai/Ashburton Lakes are a beautiful set of wetlands and lakes in the Canterbury high country between the Rangitata and Rakaia rivers. They’re important biodiversity hotspots and incredibly significant culturally for Māori – the lakes were an important seasonal mahinga kai area, and lie on the route between the east and west coasts. Today they are used by many for camping, water sports, and tramping access to the Southern Alps.
But these lakes are under threat.
Pollution from pastoral farming in the region is damaging the ecosystems, and we could very soon reach a point where these lakes are no longer able to support life.
More than 30 bird species, including wrybill and crested grebe, live in and around the lakes, along with freshwater species like upland long jaw galaxiids and tadpole shrimp, and plants like the endangered marsh arrowrush (Triglochin palustris) and pygmy forget-me-not (Myosotis pygmaea). Many of these species are found nowhere else in the world.
The lakes’ names reflect the values of the area. Collectively, Ōtūwharekai shows how they were an important Māori food source. Lake Heron was named after the kotuku – white herons who used to live there. Lake Clearwater was named for its special qualities, now almost lost.
In recent years, the lakes have become highly contaminated. Nutrients from land clearance, fertiliser, and too many cows, pollute the water, so it’s no longer fresh and clear. This is eutrophication, where the water receives an excessive amount of nutrients, especially nitrogen and phosphorus.
Eutrophication can lead to a lake ‘flipping’ and no longer being able to support plant and animal life. Once a lake has flipped, it’s incredibly difficult to restore it to a healthy state.
The pollution of the lakes has concerned locals, visitors, iwi and authorities for many years. The Ōtūwharekai lakes are shallow and naturally nutrient-poor, with slow flushing rates, so are highly sensitive and vulnerable to any land use changes. The surrounding land was once publicly owned, but through High Country tenure review, much of it was privatised, and stock rates were intensified. Land use changed from low-density sheep feeding on tussock and shrubland, to high-density cattle feeding on pasture grasses and intensive winter fodder crops fertilised by high quantities of synthetic nitrogen fertiliser. That synthetic nitrogen fertiliser moves through the cows into the soil, and across the land to streams and the lakes, driving pollution.
As pollution of the lakes has continued to grow, there have been a number of reports, reviews and processes to try to stop the lakes’ decline. But at the same time, government incentives encouraged further intensification and an increase in cows in the catchment – and successive governments refused to take necessary action to cut the pollution off at the source: synthetic nitrogen fertiliser driven by agri-industry greed.
But it doesn’t have to be this way.
The Government has a golden opportunity to make the change needed – change that these reports and reviews are pointing towards.
In late May 2023, the Ministry for the Environment released a damning indictment of the systems which have failed to keep the Ashburton Lakes, alongside 98% of other freshwater systems in Aotearoa, environmentally safe. The report, titled ‘Lessons Learnt’, identified a long list of failures – and critically, found that over 95 percent of nutrients polluting the lakes could be traced back to the land-use practices on adjacent pastoral farms.
Now, even the Government’s own reporting is saying that it’s time to regulate the agriculture industry, to stop the pollution that is destroying our freshwater lakes and rivers.
At the top of MfE’s long list of failures was that of the authority who was supposed to regulate freshwater in the region: Environment Canterbury. ECAN delegated responsibility for Farm Environment Plans (FEPs) and farm Nitrogen loss limits to third parties, leading to capture of the regulation processes by industry. Regulatory monitoring and land use data was not always adequate, transparent or accessible. FEPs relied on processes, not outcomes, and standards were set at a high, already polluted baseline for nitrogen leaching to the lakes, locking in high levels of contamination. Farmers and farm advisors set their own outcome-based pollution controls, which lacked precision, confidence, and certainty, and were not linked to inputs.
There’s a lag between pollution and the evidence of lake decline, and individual farm pollution management doesn’t consider cumulative effects. So by the time it’s obvious that farming practices are polluting freshwater, it may be too late.
Other problems were that managing outcomes relied on the Overseer nitrogen loss modelling tool, which the Parliamentary Commissioner for the Environment found wasn’t fit for purpose. The latest MfE report found that there was an overreliance on Overseer, and its failings weren’t accounted for. Keeping the lakes clean and healthy relied on voluntary farmer Good Management Practice (GMP) which was not sufficient to protect the lakes or to drive improvement in practices.
Despite the individual and cumulative effects of too many cattle and too much fertiliser polluting the lakes and wetlands, the four farms in the catchment were not breaking any rules. The problem is with the system. The farms’ resource consents locked in inflexible conditions that couldn’t be changed to adapt to new info about the lakes’ decline. Even now, two of the farms involved, have approved consents. But one farm has been waiting for its resource consent to be considered since 2018, and one farm consent has expired.
The MfE ‘Lessons Learnt’ report found the lakes were victims to competing government priorities and imperatives – growth and intensification vs conservation and water quality. In this competition, the lakes have lost.
Minister for the Environment David Parker told ECan that appropriate input limits should be set in the next land and water plan which is to give effect to the Government’s Essential Freshwater reforms. But the new freshwater management system applying to New Zealand’s ~23,000 farms is also dependent on Freshwater Farm Plans developed by farmers and their advisors, audited by the industry, and requiring significant resourcing from regional councils, which is unlikely to be achieved.
With the completion of the Lessons Learnt report the Ministry for the Environment’s role will change “to one of clarifying its expectations and monitoring continued progress, because freshwater issues in other regions also require attention”. That’s going to be a big piece of work, because only 2% of New Zealand’s freshwater is in good or very good health, as the result of nutrients and algae.
ECan staff consider that achieving new targets and limits of 67 percent to 99 percent nitrogen load reductions required to meet healthy lake outcomes, with the currently available tools, will be challenging. They expect only incremental improvements and consider that new economic tools are required.
Greenpeace Aotearoa argues that it’s the role of the Government, armed with the ongoing information about freshwater pollution, to set input controls. The Government must apply a sinking lid to phase out synthetic nitrogen fertiliser at the next fertiliser cap review in July 2023. Given the magnitude of the contaminant reductions required, land use change is also needed. Put simply, the land cannot sustain this many cows – we need to decrease the size of the dairy herd.
Unless the Government takes heed of the MfE report, and makes ongoing improvements to the current ‘Essential Freshwater’ framework, the lessons won’t be learnt at all, and the health of these lakes, and other freshwater taonga, will continue to decline. The MfE work will be wasted, the Essential Freshwater reforms will fail, and these precious lakes, and others like them across the motu, will be irretrievably lost.
The Lessons Learnt report must be a wake up call for regulators in councils and in Government. They must act to protect these lakes and freshwater across Aotearoa New Zealand. That means phasing out synthetic nitrogen fertiliser, and reducing the national cattle herd size. These actions will help protect freshwater, but also biodiversity and the climate, as well as ensuring that people across Aotearoa have access to safe and clean drinking water.
Together, we can take on the power of the agricultural industry and transform the way that we farm, to ensure that freshwater ecosystems like the Ashburton Lakes are once again able to thrive across Aotearoa.
