Water Journal : Water Journal April 2012
catchment management water APRIL 2012 113 The best that could be hoped for was that managers and the community were aware of potential impacts and that scenario planning was undertaken to be prepared for whatever eventuated. Response Action The response action taken on a regional level focussed on: • Coordination between relevant agencies; • Development of a Turbidity Decision Support System; • Establishment of "real-time" monitoring; • Community-based water quality monitoring (Ashwatch); • Protection of aquatic-dependent threatened species; • Development of processes to reduce the impact on potable water treatment; and • Continuous review of information from storm and rainfall events. Partners and Coordination Within the region strong partnerships have formed as the result of many years of working together. Following the fire, the Goulburn Catchment Water and River Contingency Planning Group, which was formed to collectively respond to waterway incidents, undertook a review of the potential risks to aquatic ecosystem health and water quality resulting from rain or storm events on the severely burnt catchments. The Group identified where action could be taken and areas in which detailed and ongoing surveillance was required. Risk Assessment Key assets identified as being at risk included the Goulburn River, Lake Eildon, Goulburn Weir and downstream irrigation systems, urban water supplies and river health. Both direct and indirect risks were identified (see Table 1). Decision Support Tool A fire event decision support system based on assumptions about turbidity levels and tributary inflows was developed as a planning tool. The tool was used to predict the water quality impacts of a number of scenarios ranging from localised severe storms to catchment-wide severe storms. For most scenarios negligible to minor changes to turbidity were predicted (negligible <5 NTU change; minor between 5 and 20 NTU change) at key locations along the river, with major impacts (> 1000 NTU) associated with very severe storms. Stakeholders agreed that responses based on coordination and liaison with alert level triggers was the most appropriate method of responding to potential events. In addition, monitoring systems already in place would be supplemented by real-time turbidity monitoring. Eventually turbidity probes were installed at key locations along the river. These could be interrogated in real time, enabling warning of events. Real-Time Monitoring Stream water quality is being assessed by real-time turbidity monitoring using turbidity probes at sites across the fire-affected areas within the Goulburn catchment. Turbidity data (see Figure 3) is collected at 30-minute intervals along with stream height and rainfall, and for most sites this data can be accessed online, except where mobile phone coverage is not available. Turbidity has been chosen as an indicator of stream water quality, mainly because it can be easily measured in situ. A number of turbidity probes have been installed at sites across the fire-affected areas. Location of sites and their installation status is as follows: • Ten sites -- monitoring of turbidity (partner access to data for management and communications); • Two sites -- monitoring for turbidity (monitoring the risk to threatened fish communities -- Barred Galaxias). Community-Based Water Quality Monitoring Prior to the wildfire of 2009, much of north-east Victoria was subjected to regional fires in December 2006. This fire affected a total area of 1,080,088 ha, spreading from Woods Point to Tatong. Most of the upper Goulburn and Broken catchments have been affected by these fires and a high increase in turbidity has been noticed in these areas after rainfall events. AshWatch was developed to raise awareness of the importance of water quality in areas affected by the bushfires. Many local residents have complained about the quality of the water as "it is usually crystal clear, but at the moment it's flowing like mud!". The Goulburn Broken Catchment Management Authority provided support for the initiatiation of a concept project by providing funding to instigate and implement the project. Sites selected after the 2006 fire were tested on a fortnightly basis for the first six months and then on a monthly basis for the following 18 months. All results from the project were reported back to the community and to the CMA. Macro invertebrate surveys, along with photo point monitoring, were conducted throughout the project. Members of the community were encouraged to come along and learn about the aquatic environment and how it was recovering from the bushfires. Table 1. Direct and indirect threats (risk). Direct Indirect High water temperatures High pH Influx of ash Increased sediment loads Increased nutrient loads Low dissolved oxygen Changes in barriers Changes in in stream debris Figure 3. Example of real-time monitoring for regional partners (turbidity v. flow).
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