Mike Joy: The heavy price of our waterways pollution

Lake Rotorua, overlooking Mokoia Island from above Wilson's Bay. Bay of Plenty Regional Council is paying a dairy farmer ...
Phil Campbell

Lake Rotorua, overlooking Mokoia Island from above Wilson's Bay. Bay of Plenty Regional Council is paying a dairy farmer to farm less intensively.

OPINION: A couple of landmark events have happened in the agriculture-water space recently that must surely shake our myopic faith in the dairy industry in New Zealand.

On September 15 Bay of Plenty Regional Council (BOPRC) announced that, in order to reduce the pollution of Lake Rotorua, it had signed a deal with a farmer to stop dairy farming. The deal is that, to save the lake, the public through taxes and rates pays the farmer to farm less intensively. This first conversion from dairy will result in 5.75 tonnes less nitrogen ending up in the lake every year.

The council has other farmers lined up to do similar deals. To halt the decline in lake-water quality, a 100-tonne reduction of nitrogen leached is required. While nitrogen is a very valuable nutrient, it becomes harmful when there is too much of it in the wrong place. Too much in lakes and rivers leads to excess algal growth. This overabundance of algae, referred to usually as algal blooms, has many harmful effects on freshwater life and on recreational opportunities.

We are faced with this excess nutrient pollution of waterways over most of lowland New Zealand, mainly from intensification of agricultural land use.  Solutions include legislating, paying polluters to stop, and then an 'ambulance of the bottom of the cliff' approach generally called "cleaning up". There are examples of all three approaches taken by different regional councils.

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Getting pollutants out of freshwater once they are in there is very difficult. It's much cheaper not to pollute in the first place. For example, trials using artificial floating wetlands to absorb nutrients show that it costs a minimum of $240 to get a kilogram of nitrogen out of the lake; to get 100 tonnes out, the wetlands would cover much of the lake. If instead a farmer in the catchment forgoes the use of one kilogram of nitrogen fertiliser (much of which would end up in the lake) the loss of revenue is less than $6.

Realising that the sensible approach is stop the pollution before it gets into the lake, the BOPRC, with the help of government clean-up funds, has set aside $40 million: that is $400 for every kilogram of the 100 tonnes of nitrogen. A similar process happened a few years back when $90 million was paid to farmers for nitrogen reductions for Lake Taupo.

I admit to unease about paying polluters to stop polluting but in many cases the farmers had no idea of the damage caused by intensification. (I hope they do now.)

There is an important issue raised here for all New Zealanders to ponder: do we save only these two lakes? Surely all of our waterways are iconic and, in their healthy state, enhance the lives of New Zealanders and we should put as much effort into saving them. If we thought all our lakes and rivers were as important as Rotorua and Taupo and applied the same rate to pay to farmers to stop polluting, the total cost is an eye-watering amount in excess of twenty billion dollars.

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This sum was calculated based on the area in dairy nationally and the average rate of nitrogen leaching. In other words, that is the cost of the damage done nationally and not paid for by the dairy industry. Reversing the argument, New Zealanders are effectively subsidising the dairy industry by more than twenty billion dollars per year, and that is not all. Through the Government's Irrigation Acceleration Fund, they are paying for the creation of new dairy production; and then, they are paying for the clean-up costs.

Forestry Crown Research Institute Scion recently published a report comparing the economics of dairy and forestry on two similar areas of land in the central plateau. The report took into account more than just nutrient clean-up costs. It included greenhouse gas emissions, other environmental impacts, employment, and other factors. If land use changed to dairy, the result was a predicted net loss for the country of $18 million. The same area of land converted to pine forests saw a net gain of $30 million. Since that study the carbon price has almost trebled (improving economics for forestry); the dairy price has dropped significantly.

It must surely be time for all New Zealanders to reassess the value of the dairy industry: the emperor is naked. Agriculture in New Zealand must be based on 'one health' for all – that is healthy animals, healthy ecosystems and healthy people. This means the only growth can be in value and agricultural diversity, and significant reductions in artificial fertilisers and intensity.

Dr Mike Joy is a senior lecturer in Freshwater Ecology and Environmental Science at Massey University Ecology Group – Institute of Agriculture and Environment.

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