HAWKESBURY NEPEAN RIVER MANAGEMENT FORUM INTEGRATED MONITORING PROGRAM for the Hawkesbury-Nepean, Shoalhaven and Woronora River Systems PREPARED BY Independent Expert Panel on Environmental Flows for the Hawkesbury Nepean, Shoalhaven and Woronora Catchments April 2004 Independent Expert Panel Members Mr Robert Wilson BA (Hons), FCPA, MACS; Independent Chair Dr David Barnes, Sinclair Knight Merz Pty. Ltd.; Bulk water and sewerage systems Dr.Keith Bishop, Freshwater Biology Consultant; Fish ecology Dr Tony Church, Sinclair Knight Merz Pty. Ltd.; Water quality Dr Ivor Growns, Department of Infrastructure, Planning and Natural Resources; Macroinvertebrate ecology Dr Eleni Taylor-Wood, Biosis Research Pty. Ltd.; In-stream and riparian vegetation Mr Ian Varley, SMEC Australia; Hydrology Dr Robin Warner, Environmental Geomorphologist; Geomorphology Dr Stuart White, Institute for Sustainable Futures; Resource economics and socio-economic assessment The Expert Panel acknowledges the support and expertise provided by associated advisers. Illustrations Conceptual model diagrams; Ros Dare, Sinclair Knight Merz Pty. Ltd Ecological processes (Plates 1 to 7); Robbie Charles Bishop-Taylor EXECUTIVE SUMMARY The New South Wales (NSW) Government established the Hawkesbury-Nepean Management Forum (Forum) to make recommendations on an environmental flow regime for the Hawkesbury-Nepean River that would incorporate the maintenance of or improvement in environmental, social and economic conditions. The establishment of the Forum arose out of the Council of Australian Governments’ Water Reform Framework of 1994 and the NSW Government’s Water Reforms of 1997. To assist the NSW government and the Forum, the NSW government appointed the Independent Expert Panel on Environmental Flows for the Hawkesbury-Nepean, Shoalhaven and Woronora Rivers (Panel). To guide the Forum’s work plan and the work of the Panel, environmental, socio-economic, and cultural objectives were established. These objectives incorporate and expand upon the NSW River Flow Objectives. The health of the Hawkesbury-Nepean, Shoalhaven and Woronora River systems has been impacted through the combined effects of river regulation, irrigation, urbanization (resulting in inputs of sewage effluent and stormwater pollution), other landuse changes, coal mining and sand and gravel extraction. Many significant advances have been made to improve river health over the last decade, mainly through the increased treatment of sewage effluent and stormwater. However, the increase in population and the continuing low rate of flows in the rivers are threatening these investments. Aquatic weeds are spreading rapidly throughout the Hawkesbury-Nepean and deteriorating water quality in some areas is compromising the health of the river, and can lead to lethal toxic events. The incidence of fish detected with diseases is above the regional average. If the decline in river health was allowed to continue it is likely that there will be increased fragmentation of fish populations, disease rates in fish will increase, water quality will deteriorate, biodiversity will be reduced and exotic plants and animals will spread at the expense of native species. The introduction of environmental flows is necessary to ensure that the rivers remain healthy. The monitoring program integrates many related matters that impact on river health. Environmental flows must be introduced within the context of a water management strategy so that the equitable and inter-generational management of the water resource can be planned. No such strategic approach to water management exists in the region. The Forum, together with the Water Chief Executive Officers Committee (Water CEOs), has developed significant elements of the water management strategy that are linked to river health outcomes. Such a strategic approach necessitates consideration of all river systems within the water supply network for Sydney, the Blue Mountains, Illawarra and Shoalhaven as well as water recycling, water conservation, alternate water resources and pollution management. Many ancillary programs have been developed by the Forum to address the strategic mechanisms associated with water resource management. Weir investigations, water sensitive urban design, integrated effluent management and institutional arrangements including land use planning, will all play an important part in protecting an environmental flow regime and the long-term viability of the region’s water resources. The greatest immediate protection of the benefits of environmental flows will result from the implementation of the Forum’s recommended Effluent Reuse Strategy. This Strategy will bring many benefits including improved security of supply for irrigators, improved weir management, reduction of nutrients to the river particularly during low flows and a potential reduction in the quantity of water needed for environmental releases from Warragamba Dam. Development of the Monitoring Program There is a vast network of streams to be assessed for river health, water resources and the associated economic, social, cultural and environmental benefits. To assist in the assessment and to identify high priority issues and evaluate the potential benefits, the Panel divided the river systems into 29 separate reaches that primarily reflect differences in physical and hydrological characteristics along the rivers. These covered the Hawkesbury-Nepean system (including the Wingecarribee River), the Shoalhaven River downstream of Tallowa Dam and Woronora River. Conceptual models were then developed from information concerning the ecology, geomorphology, hydrology, cultural and anthropogenic characteristics of each individual reach. Hydrological surrogates based on the scientific knowledge of Panel members were used to assess the environmental benefits of a series of environmental flow options shortlisted by the Forum. The recommended environmental flow regimes for the Upper Nepean, i Hawkesbury-Nepean, Shoalhaven and Woronora Monitoring Program Executive Summary Warragamba and Tallowa Dams were then selected primarily on the basis of minimising the differences in the hydrological surrogates from the modelled natural flow regimes. Modelling of the interaction between environmental flows, the proposed effluent reuse strategy and water quality in each reach was also carried out to inform the selection process. Determining the environmental, social, cultural and economic benefits of the recommended environmental flow regimes and the associated water management strategies is premised upon the fact that an adaptive management process will be implemented. This will ensure that the optimum benefits of the flow regime in contributing to river health and water management are realised. Adaptive management is an approach that suits ideally the circumstances of the Hawkesbury-Nepean, Shoalhaven and Woronora systems. It is a process based on the understanding that knowledge of the environmental, social, cultural and economic systems of a region is not always complete but is dynamic in nature and that management decisions will be inclusive of stakeholder opinions. Available information is used to formulate objectives, such as to improve the health of the river. The favoured actions are then implemented and subjected to strict monitoring. The results of the monitoring are fed back to modify the management actions until the desired outcome or objective is achieved. Adaptive management requires a monitoring program that drives and informs the process. The monitoring program described in this report, with its associated adaptive management process, is designed to ensure that the implementation of an environmental flow regime is successful in improving and preserving the environmental, social, economic and cultural health associated with these rivers. The design of the integrated monitoring program concentrated on the high priority issues identified during the river reaches assessment and was based around four components: § Fundamental hydrological monitoring. This component provides baseline information for other components of the monitoring program and to inform adaptive management. § Ecological and physical monitoring. This component addresses the impact of an environmental flow regime on a range of issues including fish abundance and community structure, habitat features, aquatic macroinvertebrates, aquatic and riparian plants, water quality (particularly temperature) and stratification. § Ancillary monitoring. This component measures improvements arising from related strategies recommended by the Forum (such as the Effluent Reuse Strategy, protection of environmental flows and the impacts of channel changes). § Social, economic, cultural and heritage monitoring. This component measures how social, economic, cultural and heritage issues affect river conditions and how they may in turn be affected by changing river conditions. In designing the program, the conceptual models were used to characterise the physical and anthropogenic ‘template’ of the reaches. The high priority issues within each river reach (or group of reaches) were then described in relation to how the environmental flows would provide ecological, social and economic benefits to the river system. Hypotheses were then developed, response variables determined for each hypothesis and field study designs and statistical analysis approaches developed for each high priority issue. A separate methodology was used to develop the social and economic and cultural