Lakes at stake despite efforts

F arms are meeting nitrate-loss limits on paper but the water downstream isn’t improving.

A recent report on the Ashburton Lakes shows that the resource management approach is not seeing a widespread lift in lake quality. This is despite all farms within the high-country catchments meeting baseline nutrient management requirements and 15 years of wetland restoration.

The lakes risk ‘flipping’ – when clear water with waterborne plants becomes murky and dominated by algae. It rings warning bells for the wider farming industry. Meeting baseline regulations may not be enough to get a healthy ecosystem, nor satisfy increasing scrutiny by markets.

The May 2023 Report ‘Otuwharekai/Ashburton Lakes lessons-learnt report: A case study examining ongoing deterioration of water quality’, ran the ruler over the effectiveness of the water plan to turn waterway health around. The report concluded that despite all farmers in the catchments being compliant with the regional plan, water quality has not improved.

It picks several holes, but the main one is shortcomings in the resource management process itself. The report said a key issue is that the original nitrogen-loss baseline was set too high to drive reductions in farm nitrate loss.

It was always an interim “hold the line” limit to prevent further intensification. It wasn’t ever going to be able to wind the clock back.

The main nutrient source (90% or more) across all Ashburton lakes is pastoral land use. Less than 10% is seepage of human wastewater at lakes Clearwater and Camp, and waterfowl waste at lakes Emma and Emily.

Environment Canterbury councillor Ian Mackenzie said the report is a bit generalised, in that each lake has a different issue and history of land use.

“A lot of waterways feeding the catchments are in conservation park, and there is a legacy of past land use too.”

Mackenzie said these high-country waterways are very sensitive, so only a little bit of nitrate and phosphorus can have a big effect.

“Acceptable nutrients’ levels in down-country waterways are far higher.”

The report said the Ministry for the Environment (MFE) proposes to fix deteriorating water quality through the Essential Freshwater package and wider resource management reforms. This includes adopting waterway health – the notion of Te Mana O Te Wai (as the primary driver of consent decision making).

The policy is balancing lake health with equal values of economic return, human health and recreation.

Tricky consenting

Mackenzie said putting Te Mana O Te Wai into practice is extremely difficult, not just for the high-country lakes, but right across Canterbury and New Zealand.

“Any consents would have to show they improve water quality and, only then, can other values be considered. But what about lifestyle block septic systems and other developments?”

The consent method is to prove there are less than minor effects.

This policy switch could see pressure on farmers to drop stock numbers further, remove stock at critical times at hot points, cease grazing in some areas and change pasture/crop types.

Whatever the policy settings, farmers in this landscape stand to lose a lot if the ship is not turned around. Some farmers see the big picture and know what the farming community stands to lose if lake health is not improved. They have made changes to management to reduce nitrogen and sediment loss – well beyond what the baseline called for.

Drive through the area and people will see fenced-off wetlands and large tussock set-backs with no- or low-stock numbers. On the flipside, some farmers do the bare minimum to meet regulations. This may no longer be good enough for markets or for proving a domestic social licence to farm – let alone ensuring the lakes stay free of algae.

A poor decision as to stocking rate, stock type or pasture type, even in one spot, may ruin it for other farmers.

Reductions will have to be big to get better water quality. The report said six lakes need nitrogen load reductions of 67% or more, and three lakes need phosphorus load reductions of 33% or more. Recent high rainfall events have added to pressure on the lakes.

Tools not always working

The tools farmers and advisers have relied on to manage compliance with the nitrate loss limit have “vulnerabilities”, the report states. These tools include farm environment plans, good management practices and Overseer. This is because the limit set using the tools “might not be well-linked to the lake outcomes”.

Overseer used averaging across what is a diverse landscape, so farmers might be guided to thinking it’s okay to intensely farm some areas as long as the whole farm is below the average stocking rate set. As a result, leaching hotspots near the lakes can occur. That might be all it takes.

The Ashburton Lakes’ consents were some of the first land-use consents to be issued under the Land and Water Regional Plan. It’s become more sophisticated now. Applicants are asked to demonstrate localised effects, not just the average nitrate loss.

It’s a NZ-wide problem. The Our Freshwater 2023 Report from MFE and Statistics NZ laid it out in April. Between 2011 and 2020, 36% of NZ lake monitoring sites improved. On the flipside, 45% of lakes worsened.

Lake health can be measured by its trophic level index (TLI). Only 2% of lakes had very good TLI levels, a combination score relating to algae, nutrients nitrogen and phosphorus, and 46% of the 3813 lakes (larger than one hectare) had poor or very poor TL1 scores.

Unsurprisingly, lakes downstream from modified land had worse trophic levels.

Attraction of being lakeside

Roll back 150 years. Lakeside farms were sought-after for ease of stock and house water, the natural boundaries, a way to transport stock and wool and a source of food. And of course, the stunning views. In 2023 these advantages still ring true, plus the added attraction of agri- or eco-tourism.

Landowners responded collectively to the 2023 Otuwharekai/Ashburton Lakes Report. Castleridge, Hakatere, Lake Heron and Mount Arrowsmith stations issued a statement saying the situation was “serious and concerning” and acknowledged the role some farming practices had played in this degradation.

They also noted the reasons for lake degradation were “varied and complex”.

All farm businesses within the catchments are part of the Otuwharekai working group – set up in 2017 to improve lake health. Interest groups and Papatipu Runanga are also members.

Most farming families have lived alongside these lakes for generations. Stewardship started well before the working group and is ongoing, with recent plans to continue fencing sensitive areas, riparian planting and “evolving farm management practices”.

The working group newsletter noted that some farmers have voluntarily relocated winter grazing in the catchment to reduce the nutrient load near waterways and lakes. This is beyond what is required in their consent conditions. Bach owners are involved. Long-drop toilets around Lake Clearwater were decommissioned in April 2022.

Farmers who have made significant changes to their farm management must find the lack of water improvements particularly frustrating. They are left feeling unsure about how far they or their neighbours have to change farm practices in the catchment to get results.

It is clear that Environment Canterbury (ECan) relies on the voluntary actions of the catchment farmers, as there are no other levers to pull. The report said ECan, together with the working group, is establishing the evidence base required for better limits and is working with the farmers on actioning non-regulatory measures.

“Given the magnitude of the contaminant reductions required, land-use change, such as livestock reductions in parts of the catchment, may be needed.”

By 2024 the updated freshwater regulations should be adopted by councils. The report suggests this will herald a philosophical shift in resource management, that is, towards prioritising the waterbody first.

Fitting this new policy in with high-country farming, so vital to community, biodiversity management and NZ’s economy, will be where the rubber hits the road.