By FoE Far North Queensland
The Turnbull government ‒ and particularly the National Party wing ‒ are promoting dams and irrigation development across Northern Australia. The government has funded a number of studies into the 'feasibility' of these dams and irrigation schemes. One such proposed dam is Nullinga on the Walsh River, located to the west of the Atherton Tableland in Far North Queensland.
A cabal of local councils, agricultural groups and the development lobby tout Nullinga Dam as a future option to supply water for Cairns and to expand irrigated agriculture in the region. The Queensland Liberal National Party lists building the dam as core party policy. But it's actually a complete lemon – and not worth the exorbitant cost to taxpayers, or the massive environmental impacts on the Walsh and Mitchell Rivers, and the Gulf of Carpentaria.
In February this year the Queensland Government released a Preliminary Business Case on Nullinga Dam and Other Options, which concluded that at present it fails to stack up on economic grounds. (The report is posted at http://buildingqueensland.qld.gov.au/business-case/nullinga-dam/)
The cost of constructing Nullinga would be substantial, estimated at $358 million, and require government finance. Once operational, the massive dam would supply just 65,000 megalitres per year, and at a premium price to water users. This is extremely inefficient compared to the existing large dam on the Atherton Tableland called Tinaroo Falls ‒ which at full capacity delivers an annual yield of around 212,000 megalitres.
The Business Case recommended other options to meet demand for water in the region – with a focus on improved management and upgrading the existing Mareeba-Dimbulah Water Supply Scheme. This Scheme supplies water for irrigators in the region via a system of reservoirs, channels and pipes. Reducing losses and improving water use efficiency of the existing infrastructure is more viable, cost effective and relatively straightforward to implement. Current losses from the Scheme are around 30,000 megalitres per year, so fixing the existing water infrastructure should be a priority.
The proposed Nullinga Dam would never supply water directly to Cairns, because it's too problematic to pipe the water from the Walsh River, through the mountains and down to the coast. Moreover, Cairns does not suffer from a water shortage and the Regional Council has adequately planned for local supply and demand measures to meet urban growth over the next 30 years. A dam such as Nullinga is simply not needed for the Cairns region into the foreseeable future.
A dam of this size would cause widespread and irreversible impacts on the environment, and many threatened species and habitats. It would permanently flood extensive areas of forests and woodlands of the upper Walsh, and also fundamentally change the natural hydrology of the river. These changes to natural flow will cascade downstream to the largely intact Mitchell River, and on productive wetlands and fisheries in the Gulf of Carpentaria. Clearing yet more land for irrigated crops also wipes out habitat for birds and other native fauna, and leads to long-term water quality problems from agricultural run-off.
Despite these substantial drawbacks, the Queensland government is now pressing ahead with a full business case assessment, because industry has lobbied government claiming a large enough demand for water. It's time governments scrapped this ill-conceived dam for good and focused instead on protecting and restoring our precious rivers.
Published in Chain Reaction #133, September 2018. National magazine of Friends of the Earth Australia. www.foe.org.au/cr133
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