Resources

Tasman Environment

12/08/2019

ENVIRONMENT

Tasman is world renown for our stunning landscapes, but we need to encourage smarter use of our environment for a sustainable future so that generations to come can also enjoy the Tasman experience. We all need to step up including Farming, Business, Tourism, and Residential households in the products we use, the way we treat our natural resources, and the flora and fauna we share the planet with.

Are you ready to see change in Tasman?

Would you like to see us protect our rapidly disappearing variety of life? Tasman is home to a number of species on the endangered, and critically endangered species list. We can act now save them or we let them slide into extinction.

It sounds like an obvious choice, but it may require taking action that restricts our “rights” as Kiwis. We may have to give up our right to racing along beaches in vehicles or taking our dogs to beaches and letting them roam free. We may have to give up our right to camp anywhere we like whenever we like.

What are the benefits, apart from saving a few birds and bugs or some plants we don’t know the name of anyway?

Tasman is one of the few regions in New Zealand with significant environments of interest that does not capitalize on this opportunity. We have national parks and we have freedom campers. We do not promote Kiwis (the bird) like Rotorua, or Whales like Kaikoura, or Penguins like Oamaru, or the Gannets of Cape Kidnappers. But why don’t we?

Eco-tourism is far more lucrative than allowing freedom camping. The money generated from eco-tourism not only creates work opportunities, it also allows for more work to be done to protect and enhance our endangered species. Is that worth a conversation about maybe giving up some of our “rights”?

STATE OF CLIMATE EMERGENCY

I do not believe making declarations of emergency is as effective as implementing a strategy of improving how we live. We can do better and we need to do better. Let’s just work together and get it done.

Why, I don’t support a state of emergency.

I absolutely support spending money to reduce our waste to landfill and to protect our endangered flora and fauna. I do not support the generation of endless reports costing huge amounts of money that would be better spent making an actual difference in building a sustainable future.
I do not support the use of emergency in this context. In 2006 Al Gore said we would reach “the point of no return” by 2016 labelling it a “true planetary emergency.” We have missed the boat according to Al.
If we keep calling labelling things an emergency that are decades away then what do we call an imminent emergency? It is like all the hi-viz and orange cones on a work site nowadays it all becomes background noise, or like the little boy who cried wolf.
There is also the fact that a “state of emergency” gives the Government of the ability to step in and take control. They may exercise full military lockdown or evacuation (like Wakefield during the recent fire state of emergency) and sequestration of whatever resources and supplies they deem necessary. Be careful what you wish for.
We have soaring rates of youth suicide and one of the reasons quoted is this feeling of despair that we are all doomed. I do not support treating our youth as political pawns to the point they are taking their own lives in despair. When I was a teenager there was the threat of peak oil and then the imminent threat of nuclear holocaust being thrust upon us, fortunately, there wasn’t the internet compounding the issue back then.

What can we do then?

While it is easy to blame agriculture, forestry and other land use for greenhouse gas emissions. And they may be responsible for 23 percent of global greenhouse gas emissions according to the recent IPCC survey.

But food waste is also a major culprit, according to a new report from the Intergovernmental Panel on Climate Change (IPCC).

From 2010-2016, global food loss and waste contributed 8-10 percent of total anthropogenic GHG emissions and currently 25-30 percent of total food produced is lost or wasted, says the IPCC report on climate change and land.

This is something that we all can do to immediately affect the amount of emissions adding to climate change. It doesn’t require more reports and endless debates at huge expense. Don’t reinvent wheel just take action.

Join other voters for a practical response to Climate Change and Environmental Issues this election.

Dam Myths and Other Effects

07/11/2018

One side of the Waimea Dam argument claim that it is an environmental benefit for our region (hence the district-wide rate increase). The other side of the argument is not so convinced, in fact, Dr Joy speaking to a packed crowd at Mapua said the claim is “utter rubbish.”

In their report titled Damn the dams Kyleisha Foote and Mike Joy discuss some of reasons that large-scale dams cannot be a benefit to the environment. One of those reasons is that in order to pay for large infrastructure land owners’ resort to synthetic nitrogen to boost returns.

The problem with nitrogen, they say, is;

Consumption of water contaminated with nitrogen can lead to certain types of cancer and has been linked with blood disease in infants, known as the blue baby syndrome. (It is thought that the ingestion of too much nitrate leads to a decreased ability of the blood to carry oxygen; infants are more susceptible than adults.

In his article, Our deadly nitrogen addiction published in The New Zealand Land & Food Annual Dr Joy digs deeper into the nitrogen issues.

Synthetic nitrogen has allowed the human population to reach double the 3.5 billion that could have been sustained without it. Since the discovery, population growth and the increase in nitrogen fertiliser production have been in sync.

Now we are on track to reach a world population of more than nine billion by 2050, nearly three times what could have been supported without synthetic nitrogen.

As with a wonder drug that only later you discover has terrible side effects, the Haber-Bosch process opened up a Pandora’s Box of problems. By exploiting in a single century energy built up over millennia, we have radically altered the ecological balance of agricultural systems.

You might say that this sounds alarmist and ask if there is any real issue here. Fortunately, Dr Joy had you in mind as he continues:

The distortion triggered a proliferation of livestock so that the food system is now responsible for more than a quarter of all anthropogenic greenhouse gas (GHG) emissions, is the dominant driver of deforestation and biodiversity loss, and is a major user and polluter of water resources.

Nitrogen is not the only fossil-derived part of the problem: oil is another culprit. On top of the nitrogen footprint, our industrial food production system now uses over 10 calories of oil energy to plough, plant, fertilise, harvest, transport, refine, package, store/refrigerate and deliver one calorie of food to be eaten by humans.

On the face of it, we seem to be going backwards with all our fast-forward methods. Future generations will look back our time of greed and see that we have consumed significant amounts of resources in a totally unsustainable fashion. It is not only resources that are being depleted at a great rate of knots.

A graphic example of the human food domination of the planet is that in the last 100 years the biomass of domestic animals on the planet quadrupled. By the beginning of this Century 98 per cent of the total biomass of mammals was humans and the animals that feed them, leaving only two per cent as wild animals.

It is not only a global cost, but the cost is also very real in New Zealand too according to Dr Joy’s research.

In New Zealand the ratio of nitrogen costs to gains is likely to be similar — put simply, they constitute a net loss for society. One facet of the environmental costs of nitrogen pollution of freshwaters can be quantified by what it costs to remove it from waterways such as lakes.

Trials in Lake Rotorua showed it cost a minimum of $250 to remove one kilogram of nitrogen from the lake, whereas to not use a kilogram of nitrogen fertiliser on farm would mean a loss of revenue for the farmer of around $6.

The Bay of Plenty Regional Council is currently paying farmers to de-intensify their farming in the lake catchment order to stop 100 tonnes of reactive nitrogen entering the lake (the estimated amount that must be reduced to stop the lake clarity declining). The regional council has a $40 million tax and ratepayer clean-up fund for the lake.

evidence against dams — Evidence of negative environmental effects from dams verses evidence of positive outcomes from dams

This conversation is very pertinent to the people of the Waimea Plains. We are being sold a dam that has great community benefit because it is an environmental magic bullet. The underground water on the plains is already under threat from Nitrogen “leakage.” With no current plan on Nitrogen management in the region there is a very real threat that short-term gains by a few irrigators could have significant environmental costs for the future as Dr Joy points out in other regions with dams:

Current irrigation dams have failed to resolve water-quality issues, contrary to what irrigation proponents have promised. For example, much environmental impact in the Opihi River from the Opuha Dam, completed in 1998, has been caused by increased intensification. Since development of the dam, nitrogen fertiliser application has increased by 132 per cent in the catchment, contributing to the increase in nitrogen concentrations seen in the Opihi River and its tributaries.

Researchers at Lincoln University have found that increased pollution and diminished flood flows, triggered by the dam, have increased the growth and proliferation of algae, particularly the mat-forming species that can turn toxic. They go on to list other adverse ecological effects in the catchment: reduced salmon spawning and trout numbers, decreased dissolved oxygen, increased temperatures, and a decline in the macroinvertebrate community index (MCI).

It is not just those using the water on their land causes major problems for the environment, the dams are also guilty of widespread devastation just by being there according to Dr Joy, Foote, and others in the scientific community.

Ecologists have singled out the damming of rivers as one of the most dramatic and widespread deliberate human impacts on the natural environment.

The ecological impact of a dam begins with the terrestrial ecosystems inundated above the dam, and reaches right down to estuaries, coastlines and river mouths. In between, there are many other negative ecological, hydrological and physical consequences, including modification of sediment and water flow restrictions to passage by fish, destruction of habitat, and diminished recharging of aquifers. The result has been irreversible loss of species and ecosystems.

Existing vegetation will be flooded if not cleared beforehand. Flooded vegetation and soil will release nutrients into the water, increasing the likelihood of algal blooms and the growth of nuisance plants. In turn, the increased photosynthetic activity (from the algae and nuisance plants) will alter dissolved oxygen levels, possibly killing fish and other life. Deoxygenated water then runs downstream or filters into groundwater.

Again, the Waimea Community Dam will be guilty of flooding large amounts of vegetation in the dam reservoir as a result of cost-cutting measures.

I am also told by the Council’s head of engineering that the wave action of this large reservoir will have no erosion effect on the catchment in which it is located as sediment flows above the dam will remain constant with or without the dam. However, sediment flows below the dam will obviously be reduced.

Large reservoirs commonly store more than 99 per cent of this sediment, and many trap upwards of 70 per cent. Sediments may store nutrients, contaminants and other elements; re-mobilisation of these components can trigger algal blooms or be taken up by organisms.

Additionally, over time, sediment build-up will reduce water storage capacity. Since construction of the Patea Dam, Lake Rotorangi has been infilling at a rate of 410,000 tonnes of sediment per year, equalling over 13 million tonnes in the 32 years of operation to 2016, or 56 truckloads per day. Upstream, the riverbed level has been raised by up to 16 metres.

As dams are not usually engineered to support the additional force of tonnes of sediment infilling may also cause dams to burst. Downstream, dams alter sedimentation regimes within rivers. As downstream sediment deposition is decreased, erosion may worsen.

The deepening of riverbeds, cutting of banks and narrowing of channels caused by erosion will lead to channel simplification and reduced geomorphological activity in the river bed (e.g. lack of bar formation and a reduction in river meandering), to the detriment of river ecosystems. Infrastructure, such as the basement of bridges, may also be affected. Without sediment to replenish lost stores, the formation of plains, deltas and beaches will be affected.

Dr Joy further expands this thought speaking to The News saying there is “nothing natural about a steady flow”.

There’s this imaginary idea that there’s this excess amount of water in a river that you can take away.

But in reality there’s not – there’s no such thing – because excessive flow is what shapes the river, it’s what washes away all the crud out of the river, it’s what shifts the sediment, it’s what opens the bar at the end and all that kind of stuff that’s crucial to the life of the river.

But what about the “flushing flows” that we will be releasing from the dam periodically? Surely, they are beneficial and help offset the environmental impact of the dam? Foote and Joy disagree:

Perhaps the most damaging and widespread impact a dam can have on a river ecosystem is caused by flow regulation In many cases, the management plan for flows from a dam only incorporates a minimum flow, despite freshwater scientists showing that the most important ecological condition in river ecosystems is the maintenance of a naturally variable flow regime. Ecological communities also require floods and other flow variations to maintain their integrity.

In New Zealand, it has been argued that flushing flows — the release of water from a dam in times of low flows — will ‘flush’ algae out to sea and provide some dilution of pollutants such as nutrients, thereby helping improve water quality. It is postulated that flushing flows mimic natural flood events that occur in unregulated rivers.

During these natural flood events, increases in water velocity strip off algae and wash it out to sea. The whole river system, including the tributaries, fills up with water, so there is a tremendous amount of power behind these flood events. Conversely, water released from a single point coming out of a dam does not have the same amount of power; energy is dissipated very quickly when it is not supported by all the tributary flows. Flushing flows are often not of adequate power to turn over gravels, scour the river bed or flush algae from the river system

True cost of the Waimea Dam — Dr Mike Joy’s counting the costs of dams

And just a couple more points in case they haven’t convinced you that there is no environmental benefit (which you are paying for in your rate bill);

Dams have negative effects on the water itself. In healthy rivers, oxygen concentrations and water temperature tend to be similar throughout. In contrast, reservoirs often have layered thermoclines — they are warm on the top and cold at the bottom — and corresponding layered oxygen concentrations; there is liveable oxygen only close to the surface.

Finally, one of the most obvious impacts of dams is to impede the passage of fish to habitats above the dams. New Zealand fish communities are dominated by diadromous species — those requiring passage between fresh water and the sea to complete their life-cycle. Consequently, they are particularly vulnerable to migration barriers.

Ecologists have found that fish communities in New Zealand differ significantly in composition above and below dams. Above dams, there is a lower percentage of diadromous species and a higher percentage of exotic species than below dams.

We are causing irreparable environmental harm to benefit the economy so at least there will be plenty of food in the future … right?

Again, Joy would dispute this claim because;

“Irrigation is locking us into a system that is doomed to fail.”

Large-scale dams make farms less resilient. In order to fund dam construction and ongoing maintenance – neither of which is cheap – a high price gets put on water for irrigation. To pay this added cost, farmers intensify.

This means greater dependency on water. If water becomes scarce, farmers are more at-risk, because they have more animals and more crops. Inevitably they become less resilient.

This sentiment is supported by the fact that one of the submitters who spoke in support of the dam commented how one year of drought impacted two years of his fruit production on the Waimea Plains. I asked him, given that the Waimea Dam only provided water security for a one in sixty-year drought, what were his backup plans in a significant drought? I was met with a blank stare suggesting that there was none.

This is important because two significant droughts within a three- or four-year period would also see other unprepared horticulturists in the same position with a severely affected return for four years. Given that they will be maximising their capital investment to make the most of the dam could that be the trigger that causes WIL to capitulate and leaves Council owning 100% of a dam?

“If you spread the money they were going to spend on a big dam out amongst small projects around the community you’ll get much more resilience and value for your dollar” Says Dr Joy to TVNZabout the Waimea Community Dam.

Are we better off, as Dr Joy says “Implementing ecological farming methods can help farmers cope with lower rainfall, improve biodiversity and build healthy soil — all essential elements for drought-resistant farming.” And should we be making that change before it is too late? Joy questions if too late might be a line we crossed some time ago:

Analysis has been done by the Stockholm Institute into ‘planetary boundaries’ to find the tipping points that must not be exceeded for humankind to continue to exist.

Its analysis showed that of the10 boundaries identified, three have already been drastically surpassed: biodiversity, the nitrogen cycle and climate change. The nitrogen cycle is more than three times the safe limit; biodiversity loss is more than 10 times the limit; and with CO at 400 parts per million in the atmosphere climate change is well past the 350 parts per million boundary.

Are there other options? Some people think so.

Restoring Australian land back to a healthy soil and happy environment

About Dr Mike Joy. [Bio ex Wikipedia]
He was a Senior Lecturer in Ecology and Environmental Science at Massey University in Palmerston North until May 2018. He is currently employed at the Institute for Governance and Policy Studies at Victoria University of Wellington

In 2009, Joy received the Ecology in Action award from the New Zealand Ecological Society. In 2011, he was awarded Forest & Bird’s Old Blue award for his research into freshwater ecology and his work bringing freshwater conservation issues to public attention.

Joy received the Royal Society of New Zealand’s Charles Flemming award for Environmental Achievement in 2013, for his contribution to the sustainable management and protection of New Zealand’s freshwater ecosystems.

Dr Mike Joy was presented with the inaugural Critic and Conscience of Society $50,000 Award Sept 2017 for his work in drawing attention to the issue of water quality in New Zealand’s rivers, lakes and drinking water.

He has authored a book, Polluted Inheritance on freshwater and the impacts of irrigation and intensive farming.

Dam What Is It Costing Me

14/11/2017

Number Crunching the Dam

One of the main questions arising around the dam is “How much is it going to cost me?”

I will endeavour to unpack the figures as they have been presented. One staff member was explaining that these are the worst-case scenario, these are not the worst-case scenario, these figures are the total currently budgeted cost should the dam come in within the $82 million figure (that includes a $13m contingency).

In this world of what I would call best-case scenario:

The Government will pay $7m from the Freshwater Improvement Fund.
Nelson City Council will contribute $5m (or TDC will contribute an extra $5m).
Crown Irrigation (CIIL) will loan TDC $10m interest free.
Waimea Irrigation (WIL) will contribute $15m.
CIIL will loan WIL $22.12m – up to $23.62m with over-runs (that TDC will underwrite to the value of $29m including costs).
TDC (you the rate-payer) will contribute $16.8m.

Total costs to the rate-payer should everything fall within contingencies is $16.8m + $10m (+ $29m underwrite).

These are the figures used to calculate how much rate-payers around the district will be contributing. Should NCC not contribute $5m that will be additional to the figures quoted, as will any cost over-runs.

To date TDC has contributed $6.5m according to figures released.

This figure includes money gathered through a targeted rate on irrigators. It does not include contributions from the Government and other sources by way of grants, and a lot of staff time and miscellaneous costs that were not directly billable. In other words, the dam project has had well over $6.5m invested in it to date, a significant portion of which has been contributed by the general rate-payer. Something to consider when contemplating should we proceed with the dam.

What Does It Cost Me?

This will depend on where you live and whether you are a water user.

The following chart gives an indication of what you might be expected to contribute by way of rates depending on your circumstances.

Everyone can expect to have the Fixed District Charge of $29 added to their rate bill each year once the dam has been constructed. Remembering that these charges will be phased in during construction so will not appear in full should a green light be given to go ahead.

Those who live in the “Zone of Benefit” can expect a charge related the capital value of your property of around $56 per million of capital value (a calculator is available on the TDC website). This zone of benefit is an arbitrary line that has been drawn approximately around the rate-payers that could potentially be supplied with TDC reticulated water from bores benefiting from the dam. The location of this zone is not an exact science and will undoubtedly cause discussion wherever it is drawn from people just on one side of the line or the other (especially if your property fall just on the rated side). It is an attempt to justify that some people will receive greater benefit than others in Tasman region.

The map of the Zone of Benefit is as follows:

If you are unsure what side of the line your property falls TDC staff will be able to clarify this for you.

On top of the District Wide $29 and the Zone of Benefit charge is also a Water User charge. For those on a council reticulated water scheme that is included in the urban water club/co-op (Motueka urban supply is not) there will be a 10% increase in your water meter charge and your per m³ charge.

In short, everyone will be paying the district rate (proposed $29) and some people will be paying either the urban water charge or the zone of benefit charge, and some people will be paying all of the above. A small minority will be paying a selection of the above AND the not insubstantial cost of affiliating to WIL.

Remember that these charges do not include an NCC failure to contribute, nor do they include the potential for the dam to over-run by an unlimited figure. Another point to remember when calculating your rate bill is that they do not include the impact that the current round of property re-evaluations will have on rates, nor do they include the effect of any other capital expenditure that the council will be budgeting for.

As a council we have been looking at the projected budget for the next Long Term Plan and it will be a challenge to put it politely for the council to remain within the 3% rate increase cap over the short term. It will also be a challenge for council to remain within the $200m self-imposed debt cap.

One of the points I disagree with the staff position on is that the money robbed from the commercial accounts to pay back the $10 million CIIL loan to council is keeping down the amount rate-payers are paying. While this money may not be charged to rates directly, it has historically been used to pay down debt (and technically it is still paying debt – dam debt) which has in turn reduced rates, or it had the potential to be used to pay for other projects. Either way, it is a cost (or loss) to rate-payers and to explain it as a saving to rate-payers is misleading in my books.

The figures quoted above, while optimistic, are the figures that Council is consulting on for your support. This round of consultation is not the final hurdle for the dam. We also have to receive confirmation that the irrigators are able to sign up 3000ha of paying customer equivalents, then we have to receive a quote that fits within our budget (probably the biggest hurdle).

In this round of consultation (which is likely the final chance for the general public to have a say) you are being asked in a somewhat indirect way if you can live with the costs as suggested. If you can, then the council would appreciate your support.

What you are not being asked is the direct question of would you like a dam? Which the mayor was publicly indicating would be asked – as late as the last round of informal consultations on the annual plan this year. Why the about face on that decision I have no idea, other than that as every good salesman learns, you don’t ask a question that has a potential “no” for an answer.

What is also not being asked in so many words, is do you approve of the irrigator subsidy in the currently proposed model. While the irrigators continue to publicly deny that they are being subsidised, this model is far from a user pays model. The irrigators are contributing nothing to the “environmental flow” portion of the dam running costs, which added up over the expected 100 year life of the dam is not insignificant. Nor are they paying their full costs of the CIIL loan because of the generous offer of the rate-payer at large to underwrite their loan saving hundreds of thousands in interest.

The impact of the irrigator subsidy is that the burden of paying for the dam has been shifted to the general ratepayer, the cost of urban water security is double the cost of irrigator supply based on the dam running costs. The question then becomes should the general ratepayer subsidize businesses that will generate almost a billion dollars to the local economy over the next ten years if the dam goes ahead?

Another point raised by staff to council in 2015 (page 20 of this agenda) was that “Council would not be acting prudently unless it ensured that all parties would be able to meet their obligations and not leave Council as the last man standing if costs exceed estimates.” The current proposal is exactly that imprudent situation where council is the last man left standing for cost overruns!

What you, the ratepayer, have to decide is can you live with the proposal as presented (as ugly and biased as it is) in order to achieve the overall benefit for the community that the end product presents? Or should you cut your nose off to spite your face (as some might describe) by making a principled decision to not support the dam model as presented – which the council will tell you is the best deal that we are ever likely to get.

The choice is yours – I look forward to hearing from you over the coming weeks.

Waimea Dam Could Be Out By A Factor Of 10

11/10/2017

One of the concerns that I have been raising within the Council Chambers (and numerous meetings and emails) has to do with stability of the dam reservoir walls. This has been a particularly pertinent issue for me since the Ratepayer has assumed the role of last-man-standing in relation to cost overruns.

To clear up the current situation about overruns the situation is that the irrigator contribution to the dam as has been advertised for some time included a $15 million dollar cash input raised through water subscriptions and a loan from the Government agency CIIL to the tune of $25 million. This total of $40 million irrigator input has since been refined. That figure includes the total amount of irrigator contribution to dam construction including any cost overrun ($1.5 million share of the first $3million overruns), and other non-capital contributions (full details in the soon to be released in the consultation document). So if you are using the previously advertised figures, then the ratepayer will be responsible for ALL other overruns.

Given that albatross around the neck of the ratepayer I have been trying to find out just what is included in our P95 (the 95% guarantee that we can build the dam on or under budget). Because I am no engineer, and I am assuming that the construction of the dam has been well reviewed, I have to accept that the figures given to construct the dam will be accurate. The greatest potential for cost overruns as I see them are contained in the reservoir (no pun intended).

Why is the reservoir an issue?

It may not be an issue, but I have been unable to get that reassurance from the information I have been presented with to date.

Geological Map of Dam Reservoir — [click to enlarge]

What I have been presented with are geological maps that indicate this area is possibly the most unstable area in the Tasman region.

What this map shows (and I apologise for the quality) with the various yellow and green shapes are the slips and slumps in the reservoir immediate boundaries. What it does not show are the slips and collapsing mountain (mount Rintoll) in the headwaters of the reservoir.

My initial concern was around the amount of sedimentation infill we can expect in the dam. This is not to be confused with a water turbidity issue, but in terms of alluvial rock and gravel infill.

When the head of Engineering came back with his findings of what engineering reports stated that the expected rate of sedimentation build up is 1000m3 (or 1000 Tons – I have had two versions) per annum and he added that that will not be an issue. In fact, he went on to add that it wouldn’t matter if their figure was out by a factor of ten times.

On that point I agree, it wouldn’t matter if their figure was out by a factor of ten in terms of impact on water storage in the reservoir. However, the fact that they could be wrong about the volume of sedimentation build up does not then become a matter of throwing zero’s at the initial result. Why 10 why not 100 or 100,000 times an incorrect figure.

If we are going to go down that road do we also say what if the price is out by ten times, instead of $82 million does it matter if it is $820 million? Or what if we say that the longevity of the dam is out by ten times, instead of a 100 year water supply solution we have a 10 year water supply solution for $82 million dollars? Or again, instead of water security for a 1 in 60 year drought it is a water security of supply for a 1 in 6 year drought event. Does a factor of ten times matter in the greater scheme of things?

Does a factor of ten times matter in the greater scheme of things?

Waimea dam site — Image Source Stuff.co.nz

I believe that if the engineer reports are not correct then we should be questioning more than just the sedimentation build up, we should be questioning their ability to ascertain the watertightness of the reservoir walls. If we start to fill the reservoir after building an $82 million dollar dam and find that the hills are leaking water so that the dam does not fill do we walk away? Or do we spend another $100 million to remediate the reservoir (ratepayer being the sole contributor)?

I could be barking up the wrong tree – as council staff would assure me. However, upon reading the Tonkin and Taylor reports that I was directed to read, I came away without the assuredness that the staff have there is not an issue here. I have included some excerpts below (emphasis mine) of these reports for those hardy enough to want to read more, or for those entirely without a life who would like to read the reports in full follow this link.

First a quick summary. Because the ratepayer is soley responsible ($1.5m excluded) of dam overrun costs this dam needs to come in on budget. Currently there is a 5% chance that this project could bankrupt the Tasman district. And by bankrupt I compare the Cromwell dam “In the end, the investigation and stabilisation work cost a staggering $936 million. Work on the Nine-Mile landslide alone, reportedly cost $60 million.” (source ). When things go wrong there is no limit to potential costs.

In the same blog refernced above there is a discussion on the Roxburgh dam – now choked with sedimentation. The Tonkin and Taylor reports highlight the number and size of existing slips along the sides of the reservoir. The figure of 1000m3 of sedimentation per annum do not reflect the volumes of gravel anecdotally moving down the river now, without the added impact of a large body of water in the valley waterlogging the toe of these 80,000m3 slips, plus the added effect of wave action. Not to mention the effects of extreme weather events or earthquakes which may not affect the dam structure but could potentially cause Kaikora scale landslides.

picture of the existing wai-iti dam — Wai-iti Dam – picture credit TDC

Wave action is one of the problems that was identified early on with the Kainui / Wai-iti Dam. As you can see this dam in entirely different country to the proposed Waimea Dam.

Another point raised by the author of the Clutha blog was in relation to decommissioning costs of the Roxburgh dam. They said that if decommissioning costs were taken into account most large dams would not be constructed. I tried to have to the cost share ratified in the Waimea dam term sheet, but I was laughed out of the council chamber. Consequently, there is no mention of who will pay for the decommissioning of the Waimea dam in the event that it becomes necessary (a little present from our generation to those who will follow trying to sort that out in court).

This information is presented purely to add to an informed debate as we enter the consultation phase for the Waimea Dam.

Following Exceprts taken from:

Lee Valley Dam Feasibility Investigations Geotechnical Investigation Report T&T Ref. 24727.204
WAIMEA WATER AUGMENTATION COMMITTEE December 2009

Geological investigations (T&T 2012) for the dam identified a number of potential slope instability or landslide features around the potential reservoir. (p7)

5.2.2 Reservoir Induced Instability

It is anticipated that the inundation of the valley to form the reservoir will raise groundwater levels by up to 45 m around the perimeter of the impoundment and this will have a local destabilising effect on slopes. During operation, reservoir levels are likely to fluctuate by up to 25 m over several weeks. The slopes that will be most affected are those that are blanketed by thick soil deposits and those where local instability is already evident. Solifluction deposits, particularly those upstream of the dam on the left bank are likely to experience surface erosion and shallow instability within the zone of drawdown and extending upslope of the maximum operating level. This may disrupt the forestry access road into Flat Creek. Elsewhere soil deposits will be locally eroded by wave action within the normal operating zone but it is unlikely that landslips will extend significantly above top water level. (p.26)

6.4 Landslide generated waves
Geological investigations (T&T 2012) for the dam identified a number of potential slope instability or landslide features around the potential reservoir. These are shown on the Reservoir Landslide Map presented in the Design Drawings. Waves generated by a landslide into or within the reservoir may have the potential to overtop the dam crest and cause damage.(p42)

Two landslides were selected for detailed hydrodynamic modelling as follows:
• Scenario 1, landslide (labelled as landslide 6 and 7 on drawing 27425-GEO-09) at
approximately ch 1400 m upstream of the dam, being the worst case likely landslide
to occur under OBFL conditions (triggered by extreme rainfall) with an approximate volume of 84,000 m3
• Scenario 2, landslide (labelled as landslide 3 on drawing 27425-GEO-09) at
approximately ch 600-800 m upstream of the dam, being the worst likely landslide to
occur under OBE and NTWL conditions (triggered by seismic event) with an
approximate volume of 80,000 m3. (p.42)

Significant quantities of felled timber have been abandoned on steep slopes in the
catchment. The possibility that the timber could mobilise during a construction flood event and need to be passed down the downstream face of the dam without damaging the mesh has been considered. Logs could potentially be mobilised by the following mechanisms:
a Logs being inundated in the area immediately upstream by water ponded behind the downstream stage. This would be low velocity water but may cause logs to float
downstream
b Logs being floated by high velocity in the river due to an extreme inflow, substantially larger than recent river flows
c Local landslips into the storage in areas where the logs are stacked.
Standing trees and felled logs that will be inundated by the final reservoir are expected to be removed for water quality purposes as part of the reservoir clearing works, and this should negate the potential for the mechanism listed as “a” above. The mechanism listed as “c” above is also expected to be negated through a process involving inspection of slopes immediately surrounding the storage for potential zones of instability and removal of any logs that could be affected by the unstable zones identified. (p.81)

Cawthron (2009) recommended that for water quality reasons the reservoir, dam site, borrow areas, spoil disposal areas and contractor site compound are clear felled of trees and vegetation and that debris is removed from the same areas. We endorse forest and debris removal as a priority, as there is otherwise the risk that the dam could be damaged by debris during construction and river diversion.
An exception to forest clearance is where there are trees that currently cover possible landslides. The geotechnical investigations (Appendix F) conclude that removing trees above reservoir level on landslides may reduce the stability of the landslides. Therefore the trees above reservoir level on the landslides identified in Appendix F should remain insitu. (p.148)

The following exceprts are taken from:

Lee Valley Dam Feasibility Investigations Geotechnical Investigation Report T&T Ref. 24727.204
WAIMEA WATER AUGMENTATION COMMITTEE December 2009

No active large landslides have been identified in the potential reservoir footprint.
However, solifluction deposits, that blanket the lower level reservoir slopes, are
subject to shallow slumping and erosion. It is anticipated that groundwater levels
will be raised by the reservoir inundation, and local instability associated with
solifluction slopes can be expected.(p.5)

3.2 Faulting and Seismicity
A number of large historical earthquakes would have been felt at the potential dam site.
The magnitude and level of ground shaking at the dam site associated with recorded
events are documented in www.geonet.org.nz are as follows:
Table 1 – Historical earthquakes
Earthquake Date Magnitude Felt Intensity
Marlborough 1848 M7.8 MMVII
Murchison 1929 M7.8 MM VII-MMIII
Inangahua 1968 M7.1 MMV-MMVI
Peak ground accelerations for these events would have been in the range <0.15g for
MMV, 0.15g-0.25g for MMVII and 0.25g-0.45g for MMVIII.
The GNS New Zealand Active Faults database
http://maps.gns.cri.nz/website/af/viewer.htm indicates that seismic hazard at the site is
dominated by the Alpine Fault (Wairau Segment) located 21 km to the south-east of the
site and the Waimea Fault located 8.5 km to the north-west of the dam site.
Research by GNS 2003 [Ref. 4] indicates that the latest estimate of the recurrence interval
for displacement on the Wairau Fault is 1,600 years. A major earthquake associated with
this fault could result in both lateral and vertical offsets and severe ground shaking in the
vicinity of the fault. The associated earthquake is estimated to be an M7.6 event.
Based on the coincidence of the elapsed time and recurrence interval, and the coincidence
of accumulated strain and single event displacement history, GNS have concluded that
there is a relatively high risk of such an event.
Many segments of the faults in the Waimea–Flaxmore fault system are active, with the
ground on the south-eastern side of the major faults being uplifted. The major faults in
the system are, from northwest to southeast, Flaxmore, Waimea, Eighty-eight and
Whangamoa. The Whangamoa Fault is approximately 3.5 km west of the potential dam
site but in this region it is not classed as an active fault. Active traces are associated with
the Waimea Fault that is located at the western end of the Wairoa Gorge (8.5 km from the
dam site).
The seismic hazard presented by the Waimea Fault has been assessed by Fraser et al, 2006
[Ref. 5]. They carried out trenching of Quaternary terrace surfaces at the mouth of the
Wairoa Gorge that have been displaced by the Waimea Fault. Three fault displacements
have been determined within the last 18,000 years with an average recurrence interval of
6,000 years. A magnitude M7.0 earthquake has been estimated for rupture of the Waimea
Fault.
There are several other faults mapped within the Richmond Ranges. The following faults
have been reviewed as part of this study as being in regional proximity to the proposed
dam, but are not considered to be active, (M Johnston pers comm).
· Lucy Creek Fault: It forms the boundary between the Caples Terrane rocks and Patuki
Melange. The contact is generally poorly exposed and varies from between 35 and
200m wide. It is offset by other faults.
· Anslow Fault: The Anslow Fault is best exposed in Anslow Creek adjacent to a culvert
on the main forestry access road to the dam site. At this locality there is a zone of
crushed Rai Formation rocks about 30 m wide. It is inferred to splay into two or more
segments north-east of the Lee Valley. The fault is assessed (M Johnston Pers Com) as
a relatively minor one and there is no evidence that it is active.
· Faults adjacent to the Croiselles Melange: Several north-east trending lineations are
associated with the Croiselles Melange and it appears that several landslides have
originated where serpentinitic rocks are sheared out along faults.
· Wards Pass and Totara Saddle Faults: The Wards Pass Fault is a relatively major fault
with a well developed crushed zone and has been traced from the Alpine Fault
northwards into the Wairoa catchment where it crosses the Lee River 3.5 km upstream
of the potential dam site. North of the dam site the fault has not been identified.
Approximately 3 km north of the proposed dam site is the Totara Saddle Fault, which
trends ENE and appears to be the most south-western part of the Queen Charlotte
Fault Zone. Neither the Wards Pass nor the Totara Saddle Fault displays evidence
indicating that it is active.
· Intraformational Faults within the Rai Formation: Several crushed and sheared zones,
trending both north-east and north-west, are recognised within the Rai Formation in
the vicinity of the project area. They are aligned parallel to the major tectonic faults
and also are common at lithological contacts. (p.15-17)

3.3.3 Reservoir Slope Features
Main Valley
Upstream of the dam site the valley is aligned in a northerly direction. The valley floor
widens upstream of Ch12,650 m through to Ch13,400 m where Waterfall Creek enters the
valley. A gently inclined alluvial fan at the mouth of Waterfall Creek overlies a broad flat
terrace in the main valley.
The right bank slopes upstream of Waterfall Creek to Ch14,000 m are characterised by
actively eroding bluffs (>45° ) rising to between 40 and 50 m above the river bed. Upslope
of the bluffs between Ch13,500 m and Ch14,000 m a landslide deposit, partly overtopped
by solifluction deposits, extends onto a terrace remnant approximately 40 m above the
river. Higher slopes are inclined at 20° to 26° and are extensively blanketed by
solifluction deposits.
On the left bank, between the dam site and Ch13,500 m the ridge rises to RL500 m. An
extensive apron of solifluction deposits lying at 20 to 35° blankets the lower slopes up to
about RL260 m. Bedrock slopes above this are inclined at 34 to 40°. A gully with gentle
gradient falling to the north, just below and parallel to the ridge crest, forms a prominent
lineament that is also evident crossing ridge lines to the south.
Slopes further upstream, and on the northern side of the Flat Creek arm are generally
steep (38 to 42°) and contain rock bluffs. In contrast, the southern slopes of Flat Creek are
more gently inclined (30-34°) and are characterised by few outcrops.
Upstream of Ch14,500 m the river is entrenched in a narrow gorge with steep bluffs rising
to about 100 m above river level on both sides of the valley. These bluffs have not been
inspected, but from aerial photographs examined, they appear to be stable.
Large landslides have formed in a variety of rock types in the head of creeks draining into
the Lee River upstream of the reservoir, but are beyond the likely reservoir extent and
have not been inspected.
Waterfall Creek Arm
Waterfall Creek enters the main valley on the true right side. Within the extent of the
reservoir it is V shaped in profile. The side slopes above the reservoir level are inclined at
38 to 42 ° on the northern side and 31 to 41° on the southern side. The slopes are planar in
profile but are incised by narrow steep sided gullies spaced at 100 to 200 m. Gullies on
the northern side are actively eroding. Flatter topography, inferred to be a landslide (LS2)
infills a tributary gully above the upstream end of the reservoir on the southern side of
Waterfall Creek. Upstream and east of the reservoir, Waterfall Creek is significantly
asymmetric in profile (northern slopes 38 to 41° and southern slopes 12 to 29°), and the
southern side of the valley is inferred to be a large bedrock landslide that is buttressed
against the northern slope.
3.4 Reservoir and Dam Site Geology
3.4.1 Rai Formation
The Rai Formation is the foundation bedrock at the proposed dam site and is the
predominant bedrock exposed in the reservoir. It consists of Palaeozoic age, moderately
strong to strong jointed greywacke (well indurated fine sandstone) and argillite (well
indurated siltstone and mudstone) that is commonly fissile. There is only limited
exposure of mudstone sequences.
Bedded sequences dominate the Rai Formation and although individual beds vary
considerably in thickness they are typically spaced at 100 mm. Bedding throughout the
area dips predominantly to the north-west and meso folding within the sequence is
common, particularly within the argillaceous rocks. Individual bedding layers are not
continuous over large distances. They appear to have been sheared prior to
metamorphism. This original bedding plane shear has been healed by quartz
recrystallisation during metamorphism (annealed). However, a preferred weakness exists
along bedding and subsequent phases of tectonic deformation and local deformation of
slopes by creep and/or seismic shaking has led to localised reshearing along bedding.
3.4.2 Star Formation
The Star Formation, dominated by indurated massive to poorly bedded greywacke, has
been mapped within the proposed reservoir near Ch14,500 m and forms much of the
upper left bank slopes of the reservoir. It also provides the main armour rock within the
active river bed.
3.4.3 Patuki Melange
The Patuki Melange outcrops in the Lee River downstream of the dam site and forms the
higher slopes to the west of the study area. It consists of blocks of indurated gabbro
dolerite and basalt rock, ranging from less than 1 m to over 1 km in size, in a serpentinitic
matrix. Investigations carried out during Stage 2 revealed a high variability in rock
quality and weathering over short distances.
3.4.4 Croiselles Melange
The Croiselles Melange is mapped locally on the ridges above the right bank upslope of
the reservoir and in the upper catchment of Waterfall Creek. It consists of blocks of
ultramafic and mafic rocks and siltstone, enclosed within a serpentinite or sedimentary
matrix. It is commonly characterised by widespread instability.
3.4.5 Alluvial Gravels
Alluvial gravels form a thin veneer over rock in the bed of the Lee River, underlie low (2-4
m above the river) terraces beside the river and are mapped in isolated terrace remnants
on the valley sides at heights of up to 60 m above the river. They are described as follows.
Low Level Terrace Gravel
Low level terrace deposits on the right bank are preserved between Ch11,700 m and
12,000 m, 12,300 m and 12,420 m, 12,540 m and 12,600 m and in a wide fan deposit at the
confluence of the Lee River and Waterfall Creek between Ch12,800 m and 13,350 m.
Low level terraces are preserved on the left bank between Ch12,100 m and 12,300 m.
The deposits consist of sandy GRAVEL, with less than 20% finer than coarse silt size.
They include rounded boulders dominated by very strong hard green, grey and purplishred
greywacke, rarely more than 0.8 m across. Clasts of weaker, finer-grained lithologies,
such as argillite, are less abundant and are considerably smaller in size. Gravel clasts are
typically unweathered and unconsolidated. The deposits vary in thickness from one to
three metres.
Mid Level and High Level Terrace Gravel
Mid Level terrace deposits up to 6 m thick occur locally on a poorly preserved rock bench
about 15 to 20 m above river bed level, and are preserved at RL170 m on the left bank at
the dam site. Isolated high level deposits, some at 40 m above the river bed and
occasional deposits at 60 m above the river bed, are preserved within the valley. At the
dam site a gravel deposit is locally preserved on the left bank in the Lee Valley Road at
RL210-215 m.
The deposits consist of silty GRAVEL. Gravel clasts are moderately to highly weathered
sandstone, well rounded and yellow or brown in colour. The fines fraction varies from
sand to silt, with some clay. These deposits are generally capped by 1 to 6 m of slope
deposits.(p.18-20)

3.4.6 Slope Deposits
Solifluction Deposits
Solifluction deposits are the product of periglacial physical erosion of bedrock through
repeated freeze-thaw cycles.
Solifluction deposits are extensively distributed on the slopes in the Lee Valley. They
locally form mappable units in excess of 10 m thick where they infill fossil gullies and
form apron deposits below steep bedrock slopes. Large deposits of solifluction are
mapped on the left abutment of the dam site and on the left bank upstream of the dam
between Ch12,700 m and 12,800 m and 13,000 m to 13,200 m. No large deposits have been
mapped on the right bank near the dam site. Solifluction deposits are not observed below
the level of the mid level terraces (i.e. in the lowest 10-20° of slope).
Solifluction deposits are stratified soil deposits, layered parallel to the slope. They are
dominatedby gravelly SAND and sandy (fine) GRAVEL with some silt and traces of clay.
Fines, when present, classify as low plasticity silt (ML). These soils are very stiff to dense.
They are yellow brown in colour and the coarse fraction clasts are moderately weathered.
Poorly graded fine to medium GRAVEL layers are occasionally present. These layers are
highly porous and contain some redeposited clay that binds the gravel clasts. The poorly
graded gravel layers are loose.
Groundwater seepage is often observed within the solifluction deposits near or at the
interface with the underlying bedrock.
Colluvium and Scree
Colluvium and scree deposits are formed by on-going slope erosion. In contrast to the
solifluction deposits that are mainly preserved within gullies or as discrete mappable
bodies, colluvium deposits are widespread and generally form a thin veneer less than
2 m thick over bedrock on slopes up to about 40°. Scree deposits are common downslope
of rock bluffs, and outcrops and in narrow gullies on steep slopes (greater than 35°and up
to 50°). They are of limited lateral extent.

Colluvium deposits are gravelly SANDS and gravelly SILTS; gravel clasts are typically
slightly weathered and include angular bedrock (scree) clasts and rounded alluvial clasts.
Scree deposits are mainly medium GRAVEL, unweathered to slightly weathered. (p.20)

Landslide Deposits
Landslide deposits, derived from bedrock or soil slide or flow are not widespread within
the immediate vicinity of the dam site, or within the margins of the reservoir but do occur
within the broader Lee River catchment.
A large bedrock landslide deposit in Rai Formation greywacke is evident on the left bank,
500 m downstream of the proposed dam site, between Ch11,700 and 11,900 m. This
landslide has developed on a steep slope (45-50°) where bedrock defects are unfavourably
oriented, and where the toe of the slope is actively eroded by a river meander.
An ancient and eroded earthflow deposit that contains debris derived from Croiselles
Melange has been mapped on the right bank at Ch13,600 m and 14,000 m overlying a rock
bench and high level alluvium at RL210 m. A large landslide deposit incorporating
Croiselles Melange and Rai Formation is also inferred upstream of the reservoir extent in
Waterfall Creek.
Rockfall deposits are locally evident at the foot of bluffs, mainly Ch13,300 m and
13,800 m on the right bank.
Landslide deposits derived from recent slippage involving solifluction, colluvium and
scree are common within steep gullies and on slopes cut to form forestry roads
but are rare on the vast majority of slopes.(p.21)

5.2.1 Existing Stability
The preliminary review of the existing stability of slopes upstream of the potential dam
site has identified no active large landslides that would extend into the reservoir area.
Small areas of active erosion are noted in the heads of many gullies, and locally, small
volume rockfall is evident downslope of rock bluffs. Existing landslides in the Waterfall
Creek catchment are remote from the reservoir and the one large landslide deposit
mapped on the right bank upstream of Waterfall Creek is largely eroded and now
blanketed by younger slope deposits.
A large landslide in Rai Formation greywacke downstream of the dam site has developed
where bedrock defects are unfavourably oriented (notably bedding strikes parallel to the
slope) and where river erosion has formed a high (150 m) slope that is inclined at 45°-50°.
No similar slope features are evident within the reservoir and, in general, slopes
underlain by Rai Formation greywacke lie at between 35 and 42°.

Solifluction deposits that are well exposed in road batters upstream of the dam blanket
the lower portion of slopes. There is historical evidence of local shallow landslips when
the slopes have been deforested, but no evidence of deep seated instability. These
deposits (which are probably in excess of 10,000 years old) are not overlain by rockfall or
bedrock landslide debris. (p.32)

5.2.2 Reservoir Induced Instability
It is anticipated that the inundation of the valley to form the reservoir will raise
groundwater levels by up to 45 m around the perimeter of the impoundment and this will
have a local destabilising effect on slopes. During operation, reservoir levels are likely to
fluctuate by up to 25 m over several weeks.
The slopes that will be most affected are those that are blanketed by thick soil deposits
and those where local instability is already evident. Solifluction deposits, particularly
those upstream of the dam on the left bank are likely to experience surface erosion and
shallow instability within the zone of drawdown and extending upslope of the maximum
operating level. This may disrupt the forestry access road into Flat Creek. Elsewhere soil
deposits will be locally eroded by wave action within the normal operating zone but it is
unlikely that landslips will extend significantly above top water level.

5.2.3 Earthquake Induced Landslides
The valley slopes will, from time to time, experience ground shaking associated with
seismic events that is of a similar magnitude to that experienced in the past. The absence
of landslide debris overlying solifluction or terrace deposits in the area to be inundated
suggests that these slopes have not failed due to large scale instability during earthquakes
during the last 10,000 years. However, as a result of the presence of the reservoir,
groundwater levels will be higher than in the recent geological past and this may increase
the risk of slope failure during shaking.Preliminary stability modelling of the western,
left slope between Ch13,000 m and 13,500 m suggests that discrete downslope movements
are only likely during MCE events. Rapid large scale collapse of slopes into the reservoir
is not considered to be a likely failure scenario. (p.33)

5.5 Leakage Potential
The Lugeon permeability testing results indicate that permeability in Class 1 and Class 2 rock is generally within the range of 1-5 Lu. However, defects will provide higher permeable pathways through the near surface rock that will require grouting or near surface foundation treatment.
Class 3 rock downstream of the left abutment has high permeability above SZ3 (Lu 1-40), and there is a potential for significant leakage where Class 3 rock underlies the upper left abutment.
Bedding parallel sheared zones may have moderate permeability parallel to the shears (Lu 5-10) but rock mass permeability through the rock between sheared zones is very low (<1Lu). SZ 8 will be intersected by the plinth low on both abutments and the surface trace will extend below the upstream shoulder. Other bedding parallel defects will also be intersected by the plinth at higher levels. Bedding is inclined downstream at 35° to 70° and is not likely to be a potential source of leakage around the abutment.
Joint Sets A and B will provide preferential leakage paths both under the dam and around the abutments as they strike parallel to the valley sides. There is a possibility that there has been some stress relief in the right abutment leading to the opening of joints producing locally moderate permeability (Lu 5-12) and there is a risk of individual seepage paths through the foundations and abutments associated with these joints. If water losses can be tolerated then the need for a grout curtain is reduced. However consequences of leakage may include piping and erosion of fines in sheared zones, and elevated pore water pressures in the slope downstream of the abutment.

Reservoir
· No active large landslides have been identified in the reservoir.
· Groundwater levels will be raised by inundation and local instability associated with solifluction slopes can be expected.
Further detailed engineering geological mapping of the full reservoir should be undertaken during the detailed design phase, and attention should be given to stability modelling of those slopes with elevated risk of slope failure in order to quantify the volumes of landslide debris that could be generated. If any areas are identified that may present a significant engineering risk, mitigation measures such as buttressing or drainage should be carried out during the construction phase. (p.44)

Buying Waimea Water Insecurity

16/09/2017

Firstly, I apologise for being a little slow on the uptake to understand and convey this, but I had to wade through talk about Hectare equivalents, 100-year security of supply, environmental flows etc. However, I now believe that I understand how the dam allocations work (or don’t work).

Who Owns The Water Behind The Waimea Dam?

From all the pretty graphics and charts, you may be under the impression, as I was, that the dam reservoir holds water capacity in three allocations; as apportioned to irrigators, environmental flow, and urban supply. And you might assume that each party owns its share of the water occupying the allocated storage capacity.

You might have been right with that assumption had there been three pipes exiting the dam. If the irrigators had a pipe that we could meter then we could shut them off when they consumed their allocation, and when the fish drank their water from the environmental flow pipe we could shut them off, and council could manage the share allocated to urban water supply via another pipe. In this scenario, the allocation percentage might make sense.

But. . . that is not the scenario that we have on the table. In the current scenario, all of the water stored behind the dam belongs to one party. Believe it or not, the fish own all the water.
Let me explain.

Because we only have one tap on the dam, and it feeds directly into the river, the only measure of control that we have is the river flow level. When the river level drops to a point that the fish dictate is unhealthy (or slightly before) we start to release water in the dam. We continue to release water from the dam in quantities that maintain happy fish until such point as there is no water left in the dam (other than a minimum level that we are required to retain), or until such time as the natural flows increase to a point where we can stop releasing from the dam.

At the point where the dam runs dry, if the drought has not broken, the fish will be unhappily flapping their fins on a hot dry river bed, the irrigators will have prunes not apples (I know apples don’t turn to prunes but you get the equivalent idea) and desperate urban supply water users will be standing on street corners in the dark of night buying bootleg water from smugglers bringing water across electorate lines. Armageddon reigns as described in the no dam scenario headlines. Fortunately, these events only occur in a greater than 1 in 60 year drought event. Although global warming proponents may find this a slightly more alarming statistic.

What all that means is that in this broken model for a dam, it doesn’t matter how many hectare equivalents council urban water club signs up for (whether one or one hundred thousand) the result is the same. Just as it doesn’t matter how many hectares the irrigators sign up for, which is probably why they over sold the need initially and then drastically reduced their intended subscription when it came to apportioning costs. In other words, the more dam debt council assumes does not translate to greater security of supply to urban water users.

Remember the fish own the water and dictate when supply is turned on, how much flow is required, and for how long the flow runs until the dam is drained (if required). The irrigators who are next in line, because their pumps are positioned above the urban water take at the mouth of the river, will use their over-allocated consents to legally pump until their hearts are content (or their permit allows). They will continue to pump while water flows down the river from the dam at a level that keeps the fish happy further exacerbating the need to release more water to keep the fish happy, until the dam runs dry. There is no mechanism to stop them pumping once their “share” of the dam reservoir is empty – and why should they, because they have a dam to pay for, and the fish will drink all the water anyway if they don’t use their share.

To top it all off, while the fish are happy drinking and the irrigators are happy pumping, the urban water users will also continue washing their cars and watering their lawns until the day that the dam runs dry. There is no incentive for urban users to cut back on water use because the dam they paid for will be releasing water to feed the irrigators (who won’t cut back) and the thirsty fish who likewise need to maintain their share flowing into the sea (we don’t want the rising sea levels to run dry after all).

So you see, it doesn’t matter who pays for what share of the dam, the fish own the water and while they are happy everyone else can use as much as they please (or are daily consented to take). That is why this model is broken. There is no incentive for anyone to conserve water at any point before the dam runs dry.

If, on the other hand, we were to look at a “plan B” option, such as the water reservoirs built on the side of the river for urban supply, then we have a different model. Water use would continue as normal until the fish said cut back. At that point, the irrigators would have to start cutting back to maintain river flows and happy fish, and urban water users would have to either start cutting back and/or start supplementing their supply from the reservoir. In this scenario, there would be an incentive for urban supply users to start reducing their demand because they only have a finite supply in store once the river drops to minimum flow.

The bonus with this model is that there is a finite supply available for urban water users that the fish cannot drink and the irrigators cannot get their pumps into. What urban suppliers pay for urban suppliers get exclusive use of. This is a security of supply model as the reservoirs can be as big as money will allow and need drives.

I am not advocating the “Plan B” as a more cost-effective model, or to have the same benefit to the fish (as clearly there is none), but it does have some merit when it comes to ensuring a security of supply. It also has the advantage of being more likely to be constructed to the P95 (95% certain it can be built on budget) than the dam scenario – but that is fodder for another post.

This post is just to help you understand what your money spent on a dam will get you, and how happy you will make the fish.

Tasman Environment

Dam Myths and Other Effects