The Manning Scheme The Manning Water Supply Scheme is MidCoast Water’s largest water supply scheme and serves the majority of our population. There currently is a large deficit between annual demand and secure yield. MidCoast Water currently sources water via Bootawa Dam which sources water from the Manning River. This supply will be complimented with supply from the Nabiac Borefield in 2018 which will supply the Manning with an average of additional 8 ML per day from the Nabiac Inland Dune Aquifer. Further reductions in water demand and improvements in operational efficiencies will have some benefit in deferring the need for large capital investments in water security and improving their affordability. However, as the planning processes for
such augmentations will be substantial, additional focus on these activities will be required in coming years. These planning processes for the Manning will need to look beyond the 30 year planning horizon. This is necessary as the options (Indirect Potable Reuse or Peg Leg Creek Dam) for augmentation from 2030 on will rely on large investments which will be financed over a long period and, in the case of the Peg Leg Dam solution, will have design lives of greater than 30 years. Securing our water supply for the Manning will have the added benefit of allowing us to move to a more sustainable extraction regime for the Manning River.
TABLE 10 – MANNING WATER SUPPLY S CHEME Current situation
Raw water is sourced from the Manning River and utilises Bootawa Dam, an off-stream 2275ML storage. This supplies a secure yield of 1730 ML/year. The current annual demand is 7,861 ML.
Description of solution
Additional supply from the Nabiac Borefield which will supply the Manning with an average of additional 8 ML per day from the Nabiac Inland Dune Aquifer. An additional solution will be required by 2030 – this will be either Indirect Potable Reuse (injecting recycled water into the aquifer) or a new off-river storage dam at Peg Leg Creek.
Towns supplied
From Coopernook in the north to Pacific Palms in the south to Krambach in the west.
Potential additional yield per year
The Nabiac Borefield will increase the secure yield to 4,650 ML/year or 4,559 ML/year if 1°C of warming is modelled. Making changes to the way Bootawa Dam is managed by relaxing the phosphorous constraint will add approximately 1,000 ML/year to secure yield. The IPR or new storage dam will add sufficient secure yield to cater for annual demands into the future (future 2045 demand for the Manning scheme has been estimated to be 11,607 ML)
Timing
The Nabiac Water Supply Scheme is planned to be commissioned in 2018. The changes to the management of Bootawa Dam will be implemented immediately.
IWCM Strategy 2015
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