‘breaking’ the 5-10-10 rule. That is, we would need to implement water restrictions for longer than 5% of the time, more often than 10% of years and/or require a reduction in water use greater than 10%. For the Bulahdelah, Stroud and Gloucester schemes, the situation would be similar, in that until off stream storage is constructed, there would be shortfall between secure yield and demand. The Tea Gardens scheme does not experience any secure yield issues.
stream storages, will depend on affordability and strategic risk assessments. Although, cost estimates and Triple Bottom Line assessments were undertaken throughout this review, they are preliminary only and a business case will need to be developed for each solution.
The timing of each of the long term water security solutions has been based on secure yield triggers (explained in the following sections). The implementation of the large secure yield solutions, such as the off-
Bulahdelah We are planning for an additional 100 million litres of raw water storage at Bulahdelah. TABLE 6 – BULAHDELAH WATER SUPPLY SCHEME Current situation
Raw water is sourced from the Crawford River Weir; a 228 ML onriver storage. This supplies a secure yield of 118 ML/year. This may decrease to 82 ML/year following 1°C of warming.
Description of solution
1x 100ML off-river storage with a possible 3rd towards the end of the 30 year planning horizon
Towns supplied
Bulahdelah
Potential additional yield per year
125 ML
Timing
1 x 100ML storage dam in 2023. Possible additional 50ML storage in approximately 2043.
Benefits
Once 100ML of additional storage is constructed, there will be additional secure yield of 125 ML/year. When 1°C of warming is modelled, this decreases to 115 ML/year. The 100ML storage will lessen the risk of severe water restrictions and will secure the water supply for Bulahdelah.
Issues
Some risk of severe water restrictions until storage dams are constructed. The existing secure yield does not meet the current and future demands. The current situation carries a high risk of not being able to supply water during a drought period.
We may also require an additional 50ML of storage in about 30 years’ time; however this will depend on population growth and the demand for water in Bulahdelah. Figure 23 shows the
IWCM Strategy 2015
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