Outlook grim for waterways

New Zealand’s destiny is tied to our 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,

Massey University professor of freshwater ecology discusses the state of our rivers and lakes

n 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.

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 instream 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.

Do you feel the way we presently monitor freshwater quality is adequate?

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 drinkdriving 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.

The NPS on freshwater is a long way from any significant protection for our rivers and streams. Russell Death says the national dairy herd should be reduced.

The latest measure of “swimmability” is based on quality at least 80 per cent of time and includes four statistical tests used