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Byron Shire
September 29, 2022

Demand management is key to our future water

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The Channon Gorge, the proposed site of the Dunoon Dam. Photo supplied.

Rous County Council’s (RCC) new Demand Management Plan (RDMP) 2023–26 is extraordinary. Parts of it could have been written by WATER Northern Rivers; the lobby group that advocates for genuinely diverse water options and the permanent shelving of the proposed Dunoon Dam.

For example, the RDMP says: ‘A key driver of this RDMP is the economic benefit of deferring or downsizing new water supply works as much as possible.

‘By reducing total water demand, the cost of building new water supplies and transferring and treating water are reduced and any capital investment required to meet the needs of growing communities may be deferred’.

Much of the RDMP supports this approach. It includes detailed residential and non-residential programs, proposes innovative water education and behavioural changes, and examines leakage reduction, smart metering, pricing, monitoring and more.

Water tanks are part of the demand management system for future water demand management. Photo Nan Nicholson

Surprisingly though, the RMDP has a lapse regarding the idea of rainwater tanks.

The RDMP acknowledges that rainwater tanks are widely supported in the community as a component of the region’s water supply. But, RCC plans to gradually eliminate tank rebates on the grounds of cost-effectiveness.

Tank rebates might not be cost-effective in the short term for RCC. However, RCC’s role in provision of water security goes far beyond cost-effectiveness. It concerns changing the culture of water use over time towards active water-conserving attitudes, and a reduction of expectations that water resources are unlimited. 

Tanks certainly change the culture of water usage, as any rural householder dependent on tank water can attest. A water tank demonstrates its limits and fits with the reality that our water resources are finite. The use of tanks reduces the drawdown on Rocky Creek Dam, even if some refills by watercarriers are required in extended dry periods.  

Tanks can be topped up by intermittent rain showers in drought when the same amount falling on a dam’s dry catchment has no runoff and cannot be collected.

Tanks in this high rainfall region can easily catch all of a household’s requirements. The average house roof area is 278m² and the average annual rainfall in Lismore and Ballina is a little over 1,000mm. This totals 278,000 litres that could be collected from an average house in a year. It would refill 18 times the 15,000-litre tank that is estimated to be sufficient for a household of three people (based on three people using 165 litres/day for 30 days without rain).

If encouraged – or even mandated – for all new housing developments, tanks could delay or avoid completely the need for risky expenditure on socially divisive infrastructure like dams or groundwater.

Water tanks or water bladders can be installed under-house or under-deck. They can be a scalable part of each development as it occurs, paid for by the developer, and do not require a large speculative outlay from distant ratepayers who will not benefit.

Lismore’s population growth pre-flood was estimated to be stalled or negative (draft NSW Far North Coast Water Strategy, 2021). Post-flood, its growth is even more uncertain. The population growth in the RCC-supplied region is mostly on the coast, in Ballina and Byron. This is precisely where the water should be collected, following the basic water management principle of collecting water as close as possible to the point where it is used.

Onsite collection of water has to be cheaper in the long run than transport over long distances, or pumping from below ground. That is, if triple bottom line accounting is used, as it should be.

Tanks provide diversity and back-up in the event of failure of the main supply. 

For instance, in the 2019–20 bushfires the water treatment plant at Rocky Creek Dam was in danger of being burnt down. This would have severely impacted RCCs ability to provide safe drinking water to the region.

Floodwater surges over the levee at Browns Creek Pumping Station, Lismore, 30 March 2022. Photo David Lowe.

Downstream evacuation 

In the 2022 floods, the dam water level came to within 600mm of the top of the wall. RCC staff were sufficiently alarmed at the prospect of wall failure to order all residents immediately below the dam to evacuate. 

Also in the 2022 floods, RCC appealed for restrained use of water owing to the huge demand for washing down houses etc that threatened drinking water supply. More tanks, constantly filling from rain at the time, would have been a useful contribution.

Large mains failures or algal contamination are infrequent but not impossible threats to a water supply overly dependent on surface water storage.

Tanks encourage a culture of self-sufficiency in the same way that solar panels encourage self-sufficiency in power. They make householders more careful of the resource and proud to contribute to the community by reducing some of the demand. 

Rous County Council shouldn’t underestimate the value of community engagement – it will be needed as climate change bites.

Has RCC quantified how much water has not been drawn from the reticulated system because of the tanks that are in use? Has it quantified how many existing and future houses could fit tanks beside or under the house? And how much water could that save? Tanks are no silver bullet, but they can have an important role to play.

The Rous Demand Management Program has much to admire, but it needs to be more ambitious in its scope, especially regarding individual responsibility for water supply.

Submissions to the Rous Regional Demand Management Plan 2023–26 are due on 12 September. See the plan here.


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14 COMMENTS

  1. I now regret going so easy on Rous in this article. Despite the wonderful motherhood statements all through the Regional Demand Management Plan, the will to make significant changes just isn’t there. Trying to ditch the tank rebate is only a small part of it.

  2. A massive cultural shift in thinking about water and what we need to support our lifestyles… hopefully we are not in the same boat as America, and we can recognize and change our limits. It is worth watching The Vanishing River: USA’s Mega Drought on Foreign Correspondent recently , as alarm bells are ringing for the way we think we should live.

  3. Rocky Creek dam came within 600mm of overtopping, that’s good design. Unfortunately it has a tiny (31 km2) catchment, but no doubt the flood control was useful. Dunoon would improve that significantly.

    • JBean, water coming within 600mm of overtopping a dam is not good design – it is good luck. With climate change predicting much more severe weather events we are going to need a lot of luck.

      The catchment of Rocky Creek Dam is actually 39 sq. km and the catchment of the proposed DuD is 19 sq. km (Rous figures). When dams are full and overflowing in a big rain event they are not providing any flood control. In fact, they exacerbate the flood peak because their surface acts as an impervious surface like a roof and causes almost instantaneous discharge of water downstream.

      The DuD could only worsen the most severe flood events.

  4. Even a tiny 450 litre tank has my water bill not go above 2 kiloliters per 3 month period.
    Last month I didn’t get charged at all.
    A small 3 kiloliter tank would be likely ideal for most houses.
    A friend has a slim-line 3 kiloliter tank (nearly 7 times bigger than mine) which fills from empty with only 20mm rain.

    Really, there’s no reason at all to even consider flooding the beautiful and precious Channon Gorge.

    We as individuals, hold the key in minimising the use of Rous water supply by storing our very OWN water.

    Here’s a $7.50 ball valve float, for automatically filling a bucket
    https://www.ebay.com.au/itm/114052176582?var=414331961108
    One inlet from the tank to the shower recess, is what was installed.
    It’s fun to use..

  5. The dam mound barrier was at no risk of failure during in the last flood, it suffered nil structural damage and is 100% intact, its not a wall its a huge mound of soil, rocks and boulders. The warnings from Rous were regarding uncontrolled flows over the spillway, ie. they had no control over the water outflows considering dam was full and catchment was still sending down huge volumes of water.

    There are already watertank mandates with new house DAs, and this volume will increase later this year when the new Building Code requires 7 star BASIX certification. Watertanks alone cannot provide all the supply, the numbers used in this letter are extremely broad in their considerations.

    eg.

    – its not economically or physically possible to hook up ALL gutters of a roof to a water tank.

    – its expensive to do underground tanks, in the coastal area there are acid sulfate soils to contend with, often creating huge costs for underground water tanks.

    – when we get a lot of rain, the tanks will often overflow, therefore the total rain volume is not correct, a large percentage will go as overflow of a full tank as the occupants can’t use enough water in that rainy time. When droughts are on, it can rain hardly at all for 3-4 months, and this is when dam storage will still be drawn down fastests, so you need more dam storage in these times.

    -industrial and commercial use a lot more water than water tanks can provide.

    in saying this, we should absolutely all have as many water tanks as possible, but I don’t see this as being a reason not to have the Dunoon Dam. Water is a critical resource, we need to store as much as possible. Yes, The landscape will be damaged by the new dam installation, but it will heal and regenerate and the new wealth from the dam can be put towards rocky creek regen 2.0 for the entire catchment between the new dam and rocky creek.

    Have you seen the photos of rocky creek dam when it was built and have you been there now? the previous weed infested cattle farm is now a ecological haven in just a matter of decades. Humans have warped time scales of our own lives, a new dam at dunoon, and a huge regen project around the dam would provide another such great outcome in the future.

    Note. Why do you always show the one photo of the lower end of the Channon Gorge when talking about the dam ( is it even the section where the new wall is? it looks like its below the proposed wall. how about you show photos of all of the dam area which is mostly cleared cow paddocks.

    I am all up for debate, if most people don’t want it then don’t do it, but why conceal the real facts about the proposal and only show the things that suit your agenda/position ?

    • I’m all for people providing their own services, but they pulled the mandatory rainwater tanks scam in SA. Once the tanks were in, they put water meters on them all and charged you for using the water out of the tank you paid for.

    • The dam earth wall was indeed at risk, according to internal Rous info. If the rain had persisted the water could well have overtopped and begun to exploit weaknesses leading to a break. That is why they had to issue this statement to downstream households: “NSWSES DAM FAILURE EVACUATION ORDER ROCKY CREEK DAM. People at your home address BELOW ROCKY CREEK DAM should evacuate now to a higher ground”.

      Nobody claimed that tanks alone could provide for the current excessive amounts used. However, I admit that my rainfall figures were too approximate at 1000 mm each for Lismore and Ballina. The real figures are 1400 mm and 1800 mm respectively.

      Yes, there are lots of reasons why tanks can’t catch every drop or provide enough in every drought. Nothing is simple or perfect. However, lack of money should not be a reason for someone not to install a tank.

      Tanks alone can’t defer the need for a dam but there are plenty of other things which can. Just eliminating the 15-18% leakage would increase supply by 15-18%. Water efficiencies for households and businesses could be seriously tackled by Rous and the LGAs. Recycling for potable and non-potable use could follow the rest of the world. Stormwater harvesting, as done in Warrnambool, could catch much of those heavy downpours which would otherwise be lost. Pricing could be used to reduce demand. The possibilities go on and on, and they are all much cheaper for the poor old ratepayer than another dam.

      I am mystified that people who support the building of the DuD always downplay its destruction of irreplaceable things.

      Eg, the landscape “damaged” includes koala habitat which would be drowned. Koalas can’t wait several decades for some replacement trees to grow elsewhere. They need every feed tree right where it is now.

      Similarly, the rainforest destroyed cannot just be recreated elsewhere, particularly that in the highly unusual conditions in the Channon Gorge where warm temperate and subtropical rainforest species meet on sandstone.

      Supporters of the DuD never mention the Widjabul Wia-bal people and their repeated refusal to accept the destruction of their living heritage. It is as if they don’t exist or their opinion has no value. Maybe mentioning them does not suit pro-dam agendas.

      Yes, I have seen the early photos of Rocky Creek dam and yes I have been there now. Regrowth forest on the farmland has been a positive effect for sure, but the destruction of freshwater ecosystems and connectivity has been catastrophic. The dam exists and we have to accept it but don’t let’s pretend that it was an unmitigated ecological good.

      As for the photo in The Channon Gorge, it is below the proposed wall and is also in the area that Rous has specified would be destroyed.

    • The picture above really has been hammered with those photoshop filters.
      Thank you for the other photos, they really do show case how perfect the place is for a dam.
      Are they going to be needing those creek rocks as fill? How would I go about getting some to build a water feature?

  6. Thanks Nan for your in depth understanding, I know I can trust the figures and insights you supply because I know you have done the research. Enough is enough. Humans are like rats shitting in our own nest! We can do better. Just remember all the unimaginable change that has happened- for example in 1900 most people didn’t have personal phones, now most of us have mobiles. We have the ability to come up with new solutions, we don’t need old expensive infrastructure like a dam here.

  7. Average water use is around 200L per person per day. A 5000L tank therefore has enough water for one person for 25 days on average if it provides all their water. A tank has only a small impact on the amount of town water used.

    • Gary, a person can drink 2 litres a day at most, with another 2 litres for cooking. The rest goes down the toilet, or the shower plughole, or on the garden.

      We don’t need to, very expensively, wreck precious irreplaceable things in order to provide high quality drinking water for toilets in poorly planned coastal developments.

      You have nailed the point about tanks – they change the amount of water that people believe they need. Check out the comment from Tim above, that he is fine with only a 450 litre tank.

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