Our freshwater health crisis - preventive medicine urgently needed

A dry-looking Selwyn River bed in early December.
Iain McGregor

A dry-looking Selwyn River bed in early December.

OPINION: In the quiet of the wee hours this first day of 2017, while reflecting on the many lakes and rivers I have worked on and loved over the past 45 years, my thoughts inevitably turned to what I have seen taking place over the years and how some of our water bodies have moved beyond the intensive care stage - beyond help and into the hospice.

Take the poor Selwyn River. Despite its vulnerability to low flows during summer, this Canterbury river was still lovely to swim in on a Sunday's picnic in the 1950s. No longer, the Selwyn is now in the hospice as are both Lakes Ellesmere and Forsyth.

But the first, and now the worst example, is Lake Tutira, a peaceful clear lake full of wildlife, native fish and trout in the early 1950s, and the most popular lake in Hawkes Bay for fishing, swimming, and picnicking.

The deterioration that took hold in the mid-1950s has rendered the lake a real cot case. Last summer, for the first time for a medium size lake in New Zealand, it become completely anoxic, meaning it had no oxygen, with dead fish and other lake denizens floating on the surface and stranded around the shoreline. Already the signs are for a repeat this summer.

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Algae in the Selwyn River in December.
Iain McGregor

Algae in the Selwyn River in December.

I could, and should, write a book about the rapid decline of Lake Tutira and all the futile attempts to turn conditions around to prevent this horrific finale. After all, my first assignment on joining the Fisheries Management Division of Agriculture and Fisheries 43 years ago was to undertake a major four-year manipulation of the lake to keep oxygen circulating through the water column of Lake Tutira during summer. 

Now my advice would be to retire farming from the entire catchment, artificially oxygenate the lake during summer and use aluminium sulphate to precipitate nutrients out of the water column and onto the lake bed. This might be achieved at a prohibitive cost but what would be the point?  It's unlikely the lake would ever regain water clarity, native weed beds and a healthy self-sustaining trout fishery.

Losing our lakes and rivers, one by one, to intensification of farming is at last beginning to impinge on the consciousness of the wider community, but why, didn't this happen years ago when the lakes and rivers were giving us all the signs that they were in trouble?

It's way too late now and nursing many of these poor water bodies back to health is unlikely. Application of fertilisers, abstraction of water from our rivers to irrigate pastures, and even the importation of huge tonnages of palm kernel as supplementary feed, all facilitate a one-way movement of nutrients from the land into our waterways.

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And it isn't just the flows, water quality and river channels that are being completely modified – landscapes too are going though a transformation in an unending bid for higher farm productivity. I began noticing very significant changes taking place while driving frequently between Canterbury and Southland and inland through the Mackenzie Country. First, all vegetation including shelter belts, were removed to leave bare ground ready for planting. Then in came the giant automated irrigation systems with their kilometre-long moving spray units dispensing water from our rivers and streams and creating green circles, like tumours, in places such as the iconic tawny landscape of the Mackenzie Basin. I was also puzzled at all the many large ponds suddenly appearing until I realised they were artificial and had been dug to capture the rain before it could even reach our streams and rivers.

And finally, to what all this manipulation is about – dairy cows. Initially herds increased to a hundred or so, but quickly herd sizes escalated and in some of the larger farms many hundreds and even thousands of cows are reared and milked. 

Dried-out weed in the Selwyn River bed.
Iain McGregor

Dried-out weed in the Selwyn River bed.

Now specially surfaced urine and dung soaking tracks are required to move cows to the milking sheds. But there's nothing more depressing than witnessing herds pugged up to their knees in mud, with no obvious feed and no shelter on a cold, wet winter's day. And we have to remember they're just the innocent victims – our wrath should be directed at those who have promoted and allowed such intensification and its effects.

And are the farmers happier and better off? With debt outweighing income it's hardly likely, as many farmers who have over-capitalised on expansion and intensification during the good times face the possibility of bankruptcy when milk and milk powder prices fall. Certainly suicide figures are an indicator of the depths of despair some dairy farmers are experiencing.

And what of our clean green image? Our burgeoning tourist industry is reliant on this branding but it seems this and the dairy industry, two of the highest earners for the country, could well be on a collision course. "No swimming" signs, putrid streams and scum-covered lakes will convey a very contradictory message to the expected millions of visitors filling our roads, picnic spots and camping sites.

The only hope for our rivers and lakes, such as lovely Lake Wanaka, that have not yet reached the intensive care unit is to take a preventative medicine approach by putting in place wide-ranging and comprehensive strategies to prevent or at least slow what seems to be an inevitable long term outcome.

Here's the fundamental question for all of us: Is the ongoing sacrifice of our, lakes, rivers and landscapes warranted?

Laurel Teirney is a fisheries and aquatic scientist, manager and facilitator who has 45 years of experience working on lakes, rivers and marine areas.

 - Stuff

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