Establishment of an integrated water quality monitoring framework for Georges Bay

This report summarises the water quality information available for Georges Bay. Data have been collected by a variety of groups, using different methods and measuring different variables over varying time periods. As a consequence, the water quality of Georges Bay has not been systematically assessed. A water quality monitoring framework for Georges Bay is clearly needed. · From the limited information available, the bay appears to be in reasonable health. Nutrient concentrations were mostly low, no herbicides or pesticides were detected in the water or animal flesh, chlorophyll a values were generally below bloom conditions and seagrass and fish populations, which are recognised indicators of environmental condition. are indicative of a healthy estuary. · However, most water quality sampling has been conducted during normal conditions, and limited data collected during flooding indicates significant deterioration of water quality during and after these events. · The results show that the current sewage treatment system is periodically not meeting acceptable standards, especially after flood events. There also has been no monitoring of stormwater outflow since 2001 and substantial development has occurred since then. It is recommended that storm water outflow is monitored, especially during and after significant rain periods. · The difference between community and expertise-based monitoring is discussed and the requirements for the two types of monitoring are detailed. A coordinated monitoring program which includes monitoring by local council, community groups and State Government agencies is essential to maximise the financial and human resources available for monitoring. The data should be held in a centralised database, with standard quality assurance procedures, and readily accessible to stakeholders. · The indicators recommended for monitoring the health of the Bay are based on the Waterwatch National Technical Manual, especially Module 7 on community estuarine monitoring (to be released in October 2005) and on the recommendations of the Tasmanian Coastal, Estuarine and Marine Indicators Working group, a group of experts developing a list of indicators to standardise estuarine and marine monitoring around Tasmania. These are summarised in Table (i) below in relation to Georges Bay, showing the list of parameters required for baseline and ongoing monitoring, frequency of sampling, and the suitability of indicators for community and expertise-based monitoring. · A template for annual assessment of the condition of Georges Bay was developed, based on criteria established by the Moreton Bay Catchment Water Quality Management Strategy Team (1998) for their Report Card reporting system for stakeholders in Moreton Bay. A mark from A to F can be assigned to Georges Bay, with ‘A’ being the highest, where the area has an ecological system that is productive and is balanced. ‘F’ is a failure, where the natural system is not functioning well and there is little or no biodiversity. · Using these criteria and information on the severity of degradation in several sections of Moreton bay, a report card was prepared for Georges Bay for the twelve months July 2004 to June 2005 (Table (ii). Georges Bay is given a ‘B’ rating, based on the data available. The Bay has healthy seagrass beds, nutrient concentrations are mostly low, although can reach high levels on occasions, no toxicants have been observed in water or oyster flesh samples and bacterial levels in the estuary are low. However, some nutrients and bacterial levels in the Georges River entering Georges Bay are high and stormwater outfalls have BOD and pH values outside the guidelines. The periodic mortality occurrences of farmed oysters in Moulting Bay is also cause for concern. A more precise classification of the health of Georges Bay would be possible if more data were available on recommended environmental parameters. · A major challenge for stakeholders of Georges Bay will be to secure the resources required, both financial and human, to complete the baseline assessment and to continue monitoring. The community, Break O’Day Council and State Government will need to work in close cooperation and all contribute to the process so that sufficient resources are available to routinely assess the condition of the Bay. This is essential to maintaining the exceptional natural assets of Georges Bay and the sustainability of the Bay community