Yes, says Iain Maxwell, Regional Manager of Fish & Game NZ. He’s talking about the upper Mohaka in the Taharua valley.

The source? This small area is home to a third of the region’s total dairy herd, some 9,000 dairy cows. Saturate a free-draining pumice soil with that many cows and the situation is right for the increased nutrient levels observed in the upper reaches of the river.

Says Maxwell: “The increase in nutrient is almost certainly the result of concentrated urine patches from 9,000 dairy cows leaching nutrient into the groundwater and then appearing in the surface waters of the nearby Taharua River.”

Lest one doubt the decline in water quality in this area of the river, watch this underwater video shot by Maxwell above and below the confluence of the Taharua and Mohaka Rivers. Above the point of their merger, clear water … below the merger, murky algae-ridden water.

These “above” and “below” photos are lifted from the video (click on photo to view full size) …

Maxwell notes that the Mohaka is the only river in Hawke’s Bay supposedly protected by a Water Protection Order, yet it appears to be deteriorating … in part because the Regional Council lacks the appropriate mechanisms in its Resource Management Plan to regulate the land use that is the suspected cause.

Fish & Game will be pushing the Regional Council on this issue. BayBuzz looks forward to the HBRC’s response to Maxwell’s video. We’ll be lending a hand however we can.

For more on the issue, here is Ian maxwell’s article, Dairying and the Mohaka, from the August issue of BayBuzz Digest.

Tom Belford

Join the Conversation


  1. It is a fact (although most of us choose to shield our minds from it) that cows produce signficantly more effluent than humans. The ratio is about 1 cow = 13 people. So if we had over 100,000 people defacating around the upper reaches of the Mohaka we would have something to say about it, but somehow we think it is ok to put that equivalent pressure on our environment via cows and not suffer consequences? I am not advocating an anti dairying position here. We just need to stop being blind to the pressures we are applying, especially in environments which cannot absorb that pressure. We often talk about the relatively sparse population in NZ. In actual fact we have a high degree of "animal" population in NZ and the effects of that population are readily apparent!

  2. How can we have a dairy unit polluting the Mohaka river which has a conservation order on it that is illegal. The HBRC should be prosecuting them off the face of the planet, oh but hang on I remember our two local MPS went up there to have a look,and they came back and said every thing was being done to stop this. The only thing that can be done to stop this pollution is to stop the farming,or put a bucket under every cows tail and cart the mess away.Looks like we have another polluted river in HB to go with all the others for so few people at the expence of everybody. This is a world renouned trout fishery in the process of been destroyed for what.


    B Strachan

  3. After speaking out on this issue in Baybuzz in February this year (Protecting the Mohaka), and chasing it up in council, HBRC is finally expecting the latest scientific research on the Mohaka to be tabled shortly- currently it is being peer reviewed by NIWA. Lots of questions need to be raised about this issue. I will keep you posted.

    Liz Remmerswaal, HBRC councillor, Hastings.

    My original article is below.

    February 28, 2009

    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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