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.
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.