Risk Description Likelihood Consequence Risk Mitigation ranking Water quality and salinity Acid sulphate soils (ASS) ASS are known to occur in Possible Moderate Medium Undertake a detailed assessment of sites suspected/known to Lake Alexandrina and Lake contain ASS to quantify the level of risk and identify appropriate Albert as well as upstream in management strategies. If water levels are maintained within the the Murray channel and levels proposed in this document, ASS are unlikely to constitute a associated wetlands major risk. (Fitzpatrick et al. 2008a, 2008b, 2009). Any unforseen reduction in flow exposing these soils would present water quality management issues for these areas. Blackwater (low dissolved Unlikely Moderate Low Assess likelihood of high flow volumes creating blackwater events in Blackwater events in the oxygen) South Australia and adopt appropriate management strategies for Murray River generally high flow events (e.g. conduct watering outside of the spring-summer originate in the upper period where possible, ensure follow-up flows to the event will occur catchment areas (i.e. central to flush any anoxic waters). Murray floodplain forests), however, they have the Work with upstream environmental water managers to ensure South potential to occur anywhere Australia is notified of backwater events and develop management that organic material is strategies to cope with such an event (e.g. ensure follow-up flows to mobilised from the floodplain. the event will occur to flush any anoxic waters). Blackwater events are likely to be diluted by the time flows reach the South Australian Blackwater events upstream border. may carry anoxic waters through to South Australia, and impact local ecology, or, they may be created in South Australia itself. Salt mobilisation during high Possible Major High Monitor salinity of flows upstream, and within, South Australia. Salt discharge into the River flows Ensure appropriate management strategies are in place to manage Murray in South Australia
Risk Description Likelihood Consequence Risk ranking Mitigation Water quality and salinity Acid sulphate soils (ASS) ASS are known to occur in Lake Alexandrina and Lake Albert as well as upstream in the Murray channel and associated wetlands (Fitzpatrick et al. 2008a, 2008b, 2009). Any unforseen reduction in flow exposing these soils would present water quality management issues for these areas. Possible Moderate Medium Undertake a detailed assessment of sites suspected/known to contain ASS to quantify the level of risk and identify appropriate management strategies. If water levels are maintained within the levels proposed in this document, ASS are unlikely to constitute a major risk. Blackwater (low dissolved oxygen) Blackwater events in the Murray River generally originate in the upper catchment areas (i.e. central Murray floodplain forests), however, they have the potential to occur anywhere that organic material is mobilised from the floodplain. Blackwater events upstream may carry anoxic waters through to South Australia, and impact local ecology, or, they may be created in South Australia itself. Unlikely Moderate Low Assess likelihood of high flow volumes creating blackwater events in South Australia and adopt appropriate management strategies for high flow events (e.g. conduct watering outside of the spring-summer period where possible, ensure follow-up flows to the event will occur to flush any anoxic waters). Work with upstream environmental water managers to ensure South Australia is notified of backwater events and develop management strategies to cope with such an event (e.g. ensure follow-up flows to the event will occur to flush any anoxic waters). Blackwater events are likely to be diluted by the time flows reach the South Australian border. Salt mobilisation during high flows Salt discharge into the River Murray in South Australia Possible Major High Monitor salinity of flows upstream, and within, South Australia. Ensure appropriate management strategies are in place to manage
ewater-delivery-river-murray.docx