Six ways to improve water quality in New Zealand’s lakes and rivers

Lake Taupo, New Zealand’s largest lake, has a nitrogen cap and trade programme in place, which allocates farmers individual nitrogen discharge allowances.

Two years ago, New Zealanders were shocked when contaminated drinking water sickened more than 5,000 people in the small town of Havelock North, with a population of 14,000. A government inquiry found that sheep faeces were the likely source of bacterial pathogens, which entered an aquifer when heavy rain flooded surrounding farmland.

second phase of the inquiry identified six principles of international drinking water security that had been bypassed. Had they been followed, the drinking water contamination would have been prevented or greatly reduced.

Here, I ask if the approach recommended by the Havelock North inquiry to prevent drinking water contamination can be extended to reduce the impacts of nutrient contamination of freshwater ecosystems.

Freshwater degraded and in decline
Most measures of the ecological health and recreational value of New Zealand’s lowland rivers and lakes have been rated as degraded and still declining. Intensive agriculture often cops much of the blame, but primary industry exports remain the heart of New Zealand’s economy.

The challenge posed by this trade-off between the economy and the environment has been described as both enormous, and complex. Yet it is a challenge that New Zealand’s government aims to tackle, and continues to rate as a top public concern.

An important lesson from the Havelock North inquiry is that sometimes there is no recipe – no easy list of steps or rules we can take to work through a problem. Following existing rules resulted in a public health disaster. Instead, practitioners need to follow principles, and be mindful that rules can have exceptions.

For freshwater, New Zealand has a similar problem with a lack of clear actionable rules, and I’ve mapped a direct link between the six principles of drinking water security and corresponding principles for managing nutrient impacts in freshwater.

Six principles for freshwater
Of the six principles of drinking water safety, the first is perhaps the most obvious: drinking water safety deserves a “high standard of care”. Similarly, freshwater nutrient impact management should reflect a duty of care that mirrors the scale of impacts. Our most pristine freshwater, like Lake Taupo, and water on the verge of tipping into nearly irreversible degradation, deserve the greatest effort and care.

Second, drinking water safety follows a clear logic from the starting point: “protecting the integrity of source water is paramount”. For nutrient impact management in freshwater, we must reverse this and focus on a more forensic analysis along flowpaths to the source of excess nutrients entering water. Our current approach of using estimates of sources is not convincing when tracers could point to sources in the same way DNA can help identify who was at a crime scene. We must link impacts to sources.

Third, drinking water safety demands “multiple barriers to contamination”. For freshwater, we’re better off taking a similar but different approach – maximising sequential reductions of contamination. There are at least three main opportunities, including farm management, improving drains and riparian vegetation, and enhancing and restoring wetlands. If each is 50% effective at reducing contaminants reaching waterways, the three are as good as a single barrier that reduces contamination by 90%. The 50% reductions are likely to be much more achievable and cost-effective.

Managing hot spots and hot moments
The fourth principle of drinking water safety was perhaps the most dramatic failure in the Havelock North drinking water crisis: “change precedes contamination”. Despite a storm and flood reaching areas of known risk for contaminating the water supply, there were no steps in place to detect changing conditions that breached the water supply’s classification as “secure” and therefore safe.

A similar, but inverted principle can keep nutrients on farm, where we want them, and keep them out of our water. Almost all processes that lead to nutrient excess and mobilisation, as well as its subsequent removal, occur in hot spots and hot moments.

This concept means that when we look, we find that roughly 90% of excess nutrients come from less than 10% of the land area, or events that represent less than 10% of time. We can identify these hot spots and hot moments, and classify them into a system of control points that are managed to limit nutrient contamination of freshwater.

Establishing clear ownership
A fifth principle for drinking water seems obvious: “suppliers must own the safety of drinking water”. Clear ownership results in clear responsibility.

Two world-leading cap-and-trade schemes created clear ownership of nutrient contaminants reaching iconic water bodies. One is fully in place in the Lake Taupo catchment, and another is still under appeal in the Lake Rotorua catchment.

These schemes involved government investment of between NZ$70 million and NZ$80 million to “buy out” a proportion of nutrients reaching the lakes. This cost seems unworkable across the entire nation. Will farmers or taxpayers own this cost, or is there any way to pass it on to investors in new, higher-value land use that reduces nutrient loss to freshwater? A successful example of shifting to higher value has been conversions from sheep and beef farming to vineyards.

As yet, the ownership of water has made headlines, but remains largely unclear outside Taupo and Rotorua when it comes to nutrient contaminants. Consideration of taxing the use of our best water could be much more sensible with a clearer framework of ownership for both water and the impacts of contaminants.

The final principle of drinking water safety is to “apply preventative risk management”. This is a scaled approach that involves thinking ahead of problems to assess risks that can be mitigated at each barrier to contamination.

For nutrient management in water, a principled approach has to start with the basic fact that water flows and must be managed within catchments. From this standpoint, New Zealand has a good case for leading internationally, because regional councils govern the environment based on catchment boundaries.

Within catchments we still have a great deal of work to do. This involves understanding how lag effects can lead to a legacy of excess nutrients. We need to manage whole catchments by understanding, monitoring and managing current and future impacts in the entire interconnected system.

If we can focus on these principles, government, industry, researchers, NGOs and the concerned public can build understanding and consensus together, enabling progress towards halting and reversing the declining health and quality of our rivers and lakes.

Troy Baisden is Professor and Chair in Lake and Freshwater Sciences at Waikato University. This article first appeared on The Conversation.


15 · Got a question about this story? Leave it in Comments & Questions below.

This article is tagged with the following keywords. Find out more about MyNBR Tags

Post Comment

15 Comments & Questions

Commenter icon key: Subscriber Verified

The big question to be answered is the water flows are so depleted that what contamination is present is so concentrated that it becomes toxic.
We need to increase the flow rates by stopping developments around the water ways and that includes farming.

Reply
Share
  • 1
  • 1

I strongly believe that what man has messed up, mankind can fix.
At the moment we have bureaucrats and "conservation scientists running around in circles playing the blame game.
1) The people who live in the catchment should be given ownership of the problem. It is their home. They are the best people to know what should be done.
2) The so-called environment councils have the regulatory authority, the democratic authority and the annual rates take to show some leadership, call the affected people together, and go from there. At the moment all they seem to do is sit around the table, suck peppermints, listen to the so-called experts submissions and play the blame game.
3) We are all in this, everyone of us. Finger pointing and playing the blame game never has, and will not, ever cleansed one litre of water. We must start now. GIVE THE PEOPLE WHO LIVE THE PROBLEM OWNERSHIP.

Reply
Share
  • 2
  • 0

Now who's pointing fingers! At a recent series of Hawkes Bay Regional Council meetings the ownership approach is exactly what is being proposed as part of the solution - and they conceded they are behind the eight ball compared to most regional councils. Ownership yes, incentives to make the necessary sea change yes, but also a stick for those who aren't prepared to pull their weight. And contrary to your observation that those in the catchment know best what needs to be done, they are in fact looking for guidance and expert advice as to how to tackle environmental issues.

Reply
Share
  • 0
  • 0

So after 30 years, yes 30 years. something might be done.
I'll believe it when I see it actually happen.
I wonder who will judge who is not "pulling weight" and, What "stick"?

Reply
Share
  • 0
  • 0

Stormwater mobilises contaminants. When we overload the land under the expectation that contaminants will assimilate and be adsorbed all we are doing is storing the nutrients for future discharge either via the surface or into groundwater. One of the problems is that intensive activities generate more contaminants and nutrients than can be managed or contained. Even a polluter pays system is still an ambulance at the bottom of the cliff approach. Applying the drinking water principles would at least get people thinking about the water cycle (catchment to tap in a drinking water sense) in a holistic way - we can learn a lot from Maori and the way they think about land, air and water.

Reply
Share
  • 0
  • 0

And in the case of drinking water supplies - mandatory chlorination.

Reply
Share
  • 0
  • 0

Start charging for Nitrogen and Phosphate leaching. The reason why we have so much in our waterways is because it is free so dump it.

Reply
Share
  • 1
  • 1

Farmers are slowly cleaning up their acts which is the way forward but importantly the government agencies also need to step up.

Reduce the use of nitrogen etc. and stop allowing water to be exported until NZ is catered for.

Reply
Share
  • 0
  • 0

Bottled water exports account for about 0.000002 percent of total water use in NZ - hardly an issue!

Reply
Share
  • 1
  • 0

Is if you are thirsty and have no water.

Reply
Share
  • 0
  • 0

Bottle water is hardly an issue, yeah right! It's like telling the Arabs oil is freely available in the Middle East, so can be freely taken. Water is a natural resource of this country, and should not be taken by foreign companies without paying tax (at least $0.10-0.15 a litre). This money can be used to build up the infrastructure of the country and clean up the waterways.

(Edited)

Reply
Share
  • 0
  • 0

Are you saying that all water evaporated in NZ that later is rained in, say Australia, should be immediately stopped.

Reply
Share
  • 0
  • 0

Always remember we are an agrarian economy. We need the farmers

Reply
Share
  • 1
  • 0

There is at least one technological fix for the nitrogen run-off problem. It consists of identifying individual urine patches and spraying them with a chemical that converts more urine into fertiliser and hence reduces nitrogen leaching.

If it was used in the Lake Rotorua catchment it would make a major reduction in nitrogen leaching and allow dairy farming to continue. The powers that be are most definitely not interested in this. They are determined to shut down farming.

Reply
Share
  • 0
  • 0

Sounds interesting Bryan:
- what is the chemical please?
- any details on the reaction equation - constituents and products (NPK ratio), whether exothermic or not etc?
- how would you propose to address issues of any excess produced fertiliser run-off into waterways?
- who do you propose would fund costs of the chemical and application?
- soil scientists are warning of serious issues relating to how we fertilise (e.g. http://www.nzherald.co.nz/the-country/news/article.cfm?c_id=16&objectid=...) - are you sure your proposed solution here is prudent in light of this?

(Edited)

Reply
Share
  • 0
  • 0

Post New comment or question

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.