uncertainties in the likelihood, timing, and magnitude of delayed salinity impacts reaching the river. Further detail on the risks and issues analysis is provided in Appendix 7 with a summary presented in Table 12. Summary Table 12 provides a description of the qualitative scoring used for the assessment of the options for SIS operations. Each option and the component of its assessment (i.e. total costs, annualised savings, impact on targets, risks / issues) has been given a qualitative score based on the in Table 12. Table 12 Description of the qualitative scoring for SIS operations Score Assessment +4 Much better than base case +2 Moderately better than base case 0 Base case -1 Moderately worse than base case -2 Much worse than base case In preparing an overall qualitative assessment score for each option, fifty percent of the weighting has been placed on costs (twenty-five percent for each of total and annualised savings), percent of the weighting on the impact on targets to 2030, and twenty-five percent of the weighting on other risks and issues. The overall qualitative assessment scores suggest that from a cost-effectiveness perspective: option 2 (86%) provides a slightly more cost-effective approach than the base case options 3 (77%) and 4 (50%) are slightly less cost-effective approaches than the base case. When considering this assessment, it is important to note that further work is required to develop more accurate costs associated with reducing SIS operations, as these costs depend on the outcome of the investigation to determine the optimal configuration of SISs. Furthermore, there is significant uncertainty associated with the predicted impact on targets and timing and magnitude of risks examined. This assessment does not account for development activities currently underway and further new accountable actions by jurisdictions that create a debit on the register and that are offset by existing credits, uncertainties of delayed salinity impacts, climate variability, or floodplain salt mobilisation due to environmental watering. Thus, further work should be considered to better understand the costs, risks, and impact on targets before any transformative changes are made to current SIS operations, and in the meantime a more precautionary approach may be appropriate. As highlighted in the Chapter 6
Option 2 – SIS 86% $ 66,010,039 $ 1,190,140 Basin Salinity Target maintained (<800 EC 95% of the time) No capacity to buffer jurisdictional use of register credits and the potential emergence of delayed salinity impacts Reduced capacity to protect river from salinity threat during extended drought when there are minimal options for mitigation with flows Some reduction in ‘headroom’ and hence some reduction in the frequency of meeting Basin Plan operational targets. Reduction of economic benefits depending upon location of schemes targeted for reduced operations Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS. Qualitative scoring of Option 2 3 3 -1 -1 Total Score Option 2 = +1
Option 3 – SIS 77% $ 72,241,170 $ 800,694 Basin Salinity Target exceeded (<800 EC 93% of time). Potential for a worse outcome if jurisdictions utilise their register credits or if there is a more rapid emergence of delayed salinity impacts Further reductions in capacity to protect river from salinity threat during extended drought when there are minimal options for mitigation with flows Reduces ‘headroom’ leading to a further reduction in the frequency of meeting Basin Plan operational targets Further reduction of economic benefits depending upon location of schemes targeted for reduced operations Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS Qualitative scoring of Option 3 +2 +2 -3 -3 Total Score option 3 = -0.5
Option 4 – SIS 50% $ 67,551,405 $ 1,093,805 Basin Salinity Target exceeded (<800 EC 89% of time). Significant reduction in capacity to protect river from salinity threat during extended drought when there are minimal options for mitigation with flows High incidence of not achieving Basin Plan operational targets Potentially a large reduction in economic benefits depending upon location of schemes targeted for reduced operations Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS Qualitative scoring of Option 4 +3 +3 -4 -4 Total Score option 4 = -0.5
Table 14 Joint program components (other elements) ID Joint program components Indicative importance and investment options Notes / other considerations Element 1: Flow management component of joint works and measures 1.1 Capture and analyse experiences in managing peak salinity events. Optimal: Assessment will be at a key site level using updated modelling. Reduced: Assessment will provide less detail (i.e. either at a sample of key sites or regional level) using updated modelling. This activity may be included as part of another major activity such as 1.2 or 4.2 1.2 Investigate ways in which dilution effects of all water in the system (including both consumptive and environmental water) could be used to enhance salinity mitigation benefits. Optimal: Assessment will be at a key site level using updated modelling. Reduced: Assessment will provide less detail (i.e. either at a sample of key sites or regional level) using updated modelling. As the environmental watering activities progress and their impacts are better understood, ways in which dilution effects to enhance salinity mitigation benefits may be developed over several years and are likely to be ongoing over the life of the BSM2030. 1.3 Develop potential approaches to flow management that seek to pursue salinity management outcomes which could be incorporated into relevant planning documents and processes. These costs are fixed as they are to be incorporated into existing planning and operational processes. However their effectiveness and robustness will be enhanced by implementation of components 1.1 and 1.2. Environmental watering strategies, priorities and schedules are expected to evolve over time. The development of approaches that provide complementary salinity outcomes will therefore also be ongoing. 1.4 Progressive review of river operation rules. These costs are fixed as they are to be incorporated into existing planning and operational processes. However their effectiveness and robustness will be enhanced by implementation of components 1.1 and 1.2. This activity may require more effort in the first years of BSM2030. However, a scaled-down ongoing effort may apply depending on future flow management decisions.
Net ‘Legacy of History’ Impacts (Register B) +5.3 +0.9 +3.4 +1 - Total Register B Balance 20 -14.01 -3.8 +0.35 -9.86 - Total Register Balance 20– All states and the River -165.2 -36.92 -26.68 -44.79 -56.12
Social, environmental, or economic impacts Maintain existing economic benefits Maintain complementary social and environmental benefits from SIS that are not explicitly considered in the approvals process for SIS. Reduction of economic benefits depending upon location of schemes (could be in the order of ~$5m/year or a 4% reduction from Option 1 ) Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS. Further reduction of economic benefits depending upon location of schemes (could be a reduction of between $5m and $18m/year or a 4%-17% reduction from Option 1 ) Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS. Potentially a large reduction in economic benefits depending upon location of schemes (could be in the order of ~$18m/year or a 17% reduction from Option 1 ) Depending upon the sites targeted for reduced operation potential loss of some environmental benefits of SIS.