Insignificant 1 Minor 2 Moderate 3 Major 4 Catastrophic 5 A (Almost certain) Moderate High Very High Very High Very High B (Likely) Moderate High High Very High Very High C (Possible) Low Moderate High Very High Very High D (Unlikely) Low Low Moderate High Very High E (Rare) Low Low Moderate High High The use of this risk matrix will assist in determining which water bodies are at high/very high risk and the appropriate course of action to be taken. The frequency and intensity of monitoring for water bodies with high or very high risk would need to be increased both during and outside bloom season. A risk based approach to manage BGA blooms is underpinned by the Australian Drinking Water Guidelines (2004). We propose 3 levels of Incident Management Response (IMR) once a bloom has been detected. Therefore these IMR levels should be based on the consequences of the bloom (given the bloom has already been detected). Table 5 shows the IMR levels once a bloom exceeds the major consequence, then it is likely to be declared an emergency and would be dealt with through the Emergency Management Manual of Victoria. Table 5 – Incident Management Response Level (based on consequence table in Australian Drinking Water Guidelines, 2004) Consequence Level Descriptor Consequence Description Incident Management Response Level 1 Insignificant Insignificant impact, little disruption to normal operation, low increase in normal operation costs. No media interest, stakeholder indifference, negligible impact on None
Incident Management Level (and characteristics of blooms) Consequences of Bloom Control Agency Monitoring Required Field Actions Required Communication Response 1 Minor Bloom detected and ≥ 0.2 mm3/L Biovolume May have waterway environmental or potential public health impacts. Can be dealt with by on site resources of a single agency There is no adverse publicity, injury, or environmental impacts No involvement of the Emergency Services Water Manager Routine cell count monitoring Visual Observations of extent and potential for off-site contamination None Inform DEPI Inform Regional Co-ordinator 2 Moderate ≥ 4 mm3/L BioVolume Toxic BGA or >50,000 cells/ml Microcystis aeroginosa or >10 mm3/L BioVolume Total BGA and One location Adverse publicity May have waterway environmental or potential public health impacts. Can be dealt with by on site resources of a single agency Local Water Manager Increase monitoring BGA cell counts (frequency) Toxicity testing Visual Observations of extent and potential for off-site contamination Erect Signs on Site Inform DHS Inform DEPI Inform Regional Co-ordinator Notify other concerned agencies Inform Press and users 3 Major ≥ 4 mm3/L BioVolume Toxic BGA or >50,000 Microcystis aeroginosa or >10 mm3/L BioVolume Total BGA and Many Locations Adverse publicity Could involve substantial risk of serious injury or death, may have serious environmental impacts, or could have public health implications. Executive level management of the issues and implications that may flow from the event. the resources of multiple agencies to deal with issues and actions Regional Increase monitoring BGA cell counts (frequency and locations) Toxicity testing Visual Observations of extent and potential for off-site contamination Erect Signs on Site Alter management to avoid BGA Alter treatment to reduce risk Inform DHS Inform DEPI Inform Regional Co-ordinator Notify other concerned agencies Inform Press and users Inform Public The actions suggested here are intended to guide the response to blue-green algae. Due to the varying toxicity and treatment of different blue-green algae species, each individual case will require an investigation and action plan.