Building on the momentum of CSIRO’s Flinders and Gilbert Agricultural Resource Assessment (FGARA) that suggested a large in-stream dam on Green Hills Station could support the development of an irrigated agriculture industry in the Gilbert catchment, Etheridge Shire Council (ESC) commissioned a detailed business case (DBC) at the site. The FGARA reports were not the first time the Green Hills site was suggested as a possible dam site, with mentions of the Green Hills dam dating back to the 1990s.
ESC interest in furthering a Gilbert River Irrigation Project was driven by the decreasing population in the region, an over reliance on grazing and limited job opportunities in the area.
The DBC was funded under the the Queensland State Government Maturing the Infrastructure Pipeline Program Stage 2 (MIPP2), with the tender being awarded to Jacobs Australia. The DBC was developed in accordance with Building Queensland guidelines.
The DBC was delivered in May 2020. The DBC assessed the proposed dam from multiple perspectives including:
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Funding The funding to construct the dam was suggested to be split into private funding from the pre-sale of water entitlements and government funding. Operational costs would be covered by annaul water charges.
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Dam design The dam would be comprised of a main dam wall, several saddle dams adjacent to the main dam wall and a delivery network comprised of a pipeline, pump stations, balancing storage, lined channels and customer offtakes.
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Dam yield The dam capacity would be over 300 GL, supplying 130 GL of water annually, catergorised by priority.
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Demand for water Demand for water, as assessed by interviews and expression of interest forms, exceeded the capacity of the dam. Demand was assessed from both current landholders and non-landholders. There was substantial interest from growers outside the Gilbert catchment.
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Area to be service by dam A total of 17,900 ha of new irrigated land could be supported with the construction the proposed Green Hills dam.
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Economic growth/job creation It was proposed that over 2,250 full time jobs would be created as a result of constructing the dam and diversifying agriculture in the region. Projected farm gate revenue was $528 million annually. The cost:benefit ratio was determined to be 1:1.15, signifying a positive economic outcome.
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Crop type Crop types suggested to be suitable are wide ranging, from high value annual crops (e.g., cotton, peanuts), high-value horticultural crops (e.g., mangoes) and rotational grain crops (e.g., pulses).
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Policy implications Water for the dam is available under the Water Plan (Gulf) 2007. Included in the dam design is outlets to meet environment flow requirements and fish passage.
Next steps
Following on from the DBC, it would necessary to commission an environmental impact statement (EIS) for the project. It is also important that the proposed Green Hills dam be declared a coordinated project. Other suggested next steps are shown below.
Resources
- Etheridge Shire Council’s Gilbert River Irrigation Project landing page, includes links to detailed business case and Gilbert River Irrigation Project summary.