In 2004 the then-Minister of Conservation, Marian Hobbs, granted a Water Conservation Order (WCO) on the Mohaka River. This protection took 17 years to achieve, instigated by the then Acclimatisation Society, now Fish and Game.

“A water conservation order is the most effective way of ensuring the outstanding fishing, recreational and scenic characteristics of the river are not compromised, and are available to future generations,” the minister said.

While the Order has prevented damming of the Mohaka, five years later, from a broader perspective, it looks as though the WCO is a sham. With ten years of intensive dairying in the Taharua valley (the upper 10% of the Mohaka catchment), and five years of scientific monitoring of water quality there, there is already evidence that river quality is declining.

For example, during last year’s Taharua hearing, HBRC scientist Brett Stansfield  showed that the quality of water at the Taharua confluence Mohaka River is being affected by intensive farming. The hearings committee agreed that “in all likelihood the nutrient runoff from general agricultural land use intensification in the Taharua catchment is having an adverse effect on water quality and periphyton growth.”
(Periphytons are aquatic plant and animal organisms that attach to objects in the bed of a body of water).

Mr Stansfield said that phosphorus from dairy farm effluent was also a nutrient of concern .  He noted that both nitrogen and phosphorus were important for periphyton growth and that periphyton biomass affected the benthic ecology (the collection of organisms living on or in sea or lake bottoms) and angler amenity of the rivers.

When growing scientific evidence concurs with layman observations, surely it’s time for  alarm bells to ring. And how is the WCO  not being compromised?

Furthermore, local iwi Ngati Pahauwera were promised increased involvement in management of the river, something they are still asking for today.

So, what is going on?

Essentially, it is a land use planning issue.

There is nothing in the current Regional Resource Management Plan to prohibit  intensive farming even on sensitive receiving environments, like the pumice soil in the Taharua. The only controls are on effluent discharges to land from a cow shed, which make up a fraction of the problem, compared to the all day toileting habits of a large herd grazing by a river.

The issue is complicated by the effect of time lags, such as has been seen in the nutrient contamination of Lake Taupo from land use activity in its pumice catchment. There the problem has been caused by decades of contamination and will take twice as long and tens of millions to fix.

Given the circumstances, you would have to wonder why a precautionary approach is not allowed for.  Changing the regional plans is a time consuming process that takes years. It can be hard to anticipate what future scenarios will be like. Complicating our motto of ‘safeguarding the environment’ is the fact that we are also responsible for the economic wellbeing of the region, which means in effect trying to balance environmental and economic values.

It is obvious that we at the Regional Council have some serious work to do, not only in research but also action. Let’s hope we can now make it a priority to get it done.

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