50 questions about the environment: Our rivers

Protecting the ecological health of our rivers and lakes means we also protect our own health, freshwater ecologist Professor Russell Death says. Photo / File

New Zealand's destiny is inextricably tied to that of its celebrated environment. But our blue and green backyard is now under unprecedented pressure from a wave of pests and human activity, ranging from development and pollution to climate change and tourism. In the first part of our week-long series, 50 Questions About the Environment, Massey University professor of freshwater ecology Russell Death discusses the state of our rivers and lakes.

In terms of nationwide trends, how would you describe the big picture at the moment? Is it better, worse or more or less about what we see in news reports?

I think it is pretty much as you hear reported in the news most days.

Toxic algae blooms in rivers and lakes all over New Zealand; increasing nitrates in Canterbury groundwater; four deaths from the Havelock North incident; and drinking water all around the country below standard.

We have low flows in rivers, partly from the warm summer, but also because we abstract a lot of the water for us to use.

To have a "pristine" lake like Taupo developing toxic benthic cyanobacterial blooms must surely be a sign that everything is not good in "clean green New Zealand".

It constantly surprises me that people tend to brush off these multiple recurring events as isolated instances.

Surely, most people can see that these events are increasing in severity, occurrence and extent all over New Zealand.

And yes, while climate changes are contributing, so too is the continued intensification of agriculture.

Massey University professor of freshwater ecology Russell Death. Photo / Supplied

What are the principal drivers of freshwater degradation? What pollutants, from which sources, are doing the most damage?

In New Zealand, intensified agriculture is driving the decline in freshwater.

This agriculture increases in-stream nutrients - nitrogen and phosphorus - and deposited sediment.

These two pollutants are by far the most pervasive in New Zealand but are almost invisible to most Kiwis visiting rivers and lakes.

How has this changed over the past few decades, and why? Where are the worst parts of the country for degradation?

Many aspects of ecological health and water quality have declined precipitously in the last few decades because of the massive conversion of sheep and beef farms to dairy, and the further intensification of dairy farms.

In terms of severity the worst areas are still in urban and industrial areas.

But they are proportionally a very small length of stream affected.

Whereas the intensified dairy areas of Waikato, Manawatu, Taranaki, Canterbury and Southland have the greatest length of stream where ecological health is degraded.

Irrigators in Canterbury, where some of the most pronounced effects on freshwater quality have been observed. Photo / File

Do you feel the way we presently monitor freshwater quality is adequate? Are there better or more robust indicators we should be using and is there still too much divergence between councils and agencies?

Monitoring is really good, but clear, unambiguous reporting of the data could be improved.

The problem is a lack of significant action on the reported declining water quality.

Are our policy frameworks strong enough to protect our waterways? Do you feel the recently-updated National Policy Statement (NPS) on Freshwater Management needs improving to better address the issue?

I do not think the NPS freshwater adds anything to water quality improvement in New Zealand.

It is good to have environmental bottom lines put in place for freshwater.

But they have to be for measures that are important to water quality.

For example, there are no nitrogen or phosphorus limits for rivers, but we do have them for lakes.

Nitrogen is present in the NPS freshwater as a toxin, but that is like having the blood alcohol drink driving limits set at when the alcohol starts acting as a poison, not when it starts making us sick or impaired.

The same applies for nitrogen: it starts impairing ecosystem health long before it gets to the levels listed in the NPS.

I have researched what the nitrogen and phosphorus limits should be for environmental health in New Zealand - see the Freshwater Rescue Plan launched this year - but no one seems to want to use them.

There are no limits for the amount of water and the pattern of flushing flow floods.

There are no limits for deposited sediment, which, with nutrients, is one of the two main pollutants in New Zealand rivers.

There is also nothing about habitat; you can have lots of clean water but if there is nowhere for the animals to live - like around stones, boulders, logs, undercut banks - there will not be a healthy ecology.

Agriculture has contributed to the decline of many of New Zealand's waterways. Photo / File

The NPS on freshwater is a long way from any significant protection for our rivers and streams.

Specifically, the latest measure of "swimmability" is based on quality at least 80 per cent of time and includes four statistical tests used for determining which rivers are excellent, good, fair, intermittent or poor, and clarifies the risk as less than 1, 2, 3 and 7 per cent respectively. Is this the right way to be measuring if waterways should be "swimmable"?

I am an ecologist and don't feel suitably qualified to address this microbial assessment.

But what I do see is that the prevalence of water-borne diseases is on the increase in New Zealand and we should be doing everything we can to protect people's lives and health.

I have linked E coli numbers - human health - to MCI - macroinvertebrate community index, or ecological health - and if you protect ecological health you will also protect human health.

Ecological health is declining because of intensification of agriculture.

Environment groups have called for a cull, or lid, on the national dairy herd. Do you feel such a move would make a meaningful difference? Further, recent research found much contamination was in smaller waterways not being captured by fencing requirements. What sweeping actions, that you haven't touched on already, do you feel are needed to stem degradation? And do you feel the collaborative approach that New Zealand has taken through the Land and Water Forum is still the right way to go?

The financial returns for dairy farming look to me in the future to be on the decline, so for economic reasons alone I think we need to start reducing the national dairy herd.

To me it is not so much one rule to fit them all.

Farmers need to farm to the limits of their land - and water.

I think many farmers are misinformed about what the best thing to do for their farm is.

Just fencing stock out of waterways might not be the right solution.

An adult giant kokopu, the largest of New Zealand's five native whitebait species, is one of those now threatened. Photo / File

If the fence is right next to the stream, with no vegetation growing in the riparian on flat peat land it is a complete waste of time and money as any sediment, nutrients and pathogens just wash straight in with any rain.

I am developing a phone app so farmers can enter the farm characteristics and water quality problems and it will figure out what the best kind of riparian solution will be to have an effective outcome for the stream health.

We need more informed solutions for farmers, who want to do the right thing, so that they really can do things that will benefit the waterways.

I do not think the collaborative approach has worked.

It tends to devolve to the lowest agreeable terms which is often to do very little or nothing until we know for sure.

Things have got too bad now we have to start doing more truly effective actions, not having countless meetings to only decide that "it's a real issue and we must do something".

Let's just do what we know we should.

We have most of the science clear; many people just don't like the answers.

Fellow Massey University freshwater ecologist Dr Mike Joy often points out the decades of nitrate use that will see these pollutants leaching into waterways for many years to come. How might such legacy problems undermine gains we are trying to make today?

Yes, it's definitely an issue for the future, but I don't like to think the "cancer" of our rivers from pollution is terminal.

So let's do something now while we still can.

We can not go back in time.

River systems do not tip over like some ecosystems, they just get slowly sicker and sicker.

"River systems do not tip over like some ecosystems, they just get slowly sicker and sicker," Professor Russell Death says. Photo / File

They will never be what they were - but they can certainly be a lot healthier than they are currently.

The latest stocktake by the Ministry for the Environment and Statistics New Zealand found that, of the 39 native fish species covered by the report, 72 per cent were either threatened with, or at risk of, extinction. How grim is the outlook for our freshwater species?

As of right now I think the future for river ecology and Kiwis' ability to swim and enjoy our water - just look in the news - is very grim.

But as with Steve Austin and The Six Million Dollar Man, we can rebuild, restore and save them.

We just need to do the right thing for the right stream.

Fence the correct riparian width for the farm type you have or fix the urban sewage infrastructure.

It's not really rocket science. We just need to do it.

And perhaps if the Government and the agricultural industry was showing more leadership, we would.

We've now seen New Zealand's freshwater problems reported on by major outlets like The Guardian, The New York Times, The Economist and Al Jazeera. Do you feel our clean, green image is sustainable if we can't tackle the issue?

The image is almost gone, I think.

And like virginity, once it is gone, it is gone.

We have lots of foreign students who come through the university and they are all telling me the pristine view of "Hobbiton New Zealand" is rapidly disappearing.

I always conclude my public talks by saying we can only fool people for so long.

It seems the international press has already figured it out.

The Series

TODAY: Our rivers and lakes
TOMORROW: Our nature
WEDNESDAY: Our climate
THURSDAY: Our biosecurity
FRIDAY: Our coasts and oceans