Cairns Regional Council Water and Waste Mulgrave River Aquifer Feasibility Study Public Environment Report November 2009 Contents Executive Summary i Abbreviations ix Glossary of Terms x 1. Introduction 1 1.1 Background 1 1.2 Objectives and Scope 1 1.3 Background to the Development of the Action 4 1.4 Relationship of the Action to Other Actions that May be Affected 5 1.5 Current Status of the Action 5 1.6 Consequence of the Action Not Proceeding 5 2. Description of the Action 7 2.1 Location 7 2.2 Detailed Proposal 10 2.3 Additional Licences / Permits and Approval Requirements required by the Project 15 3. Methodologies 23 3.1 Background and Approach 23 3.2 Demarcation of the Aquifer study area 23 3.3 Overview of Ecological Values Descriptions 26 3.4 PER Guidelines 26 3.5 Desktop and Database Assessments 27 3.6 Environmental Flows Assessment 30 3.7 Bore Testing and Modelling Verification 31 3.8 Derivation of Risk Assessment Methodologies 34 3.9 Stakeholder and Community Engagement 37 4. Description of the Environment – Physical Aspects 40 4.1 Information Sources 40 4.2 Climate 40 4.3 Topography 41 4.4 Surface Drainage Features 43 4.5 Soils 43 42/15610/99537 Mulgrave River Aquifer Feasibility Study Public Environment Report 4.6 Geology 48 4.7 Hydrogeology 51 4.8 Groundwater 53 4.9 Social Environment 54 5. Description of the Environment – Ecological 57 5.1 Information Sources 57 5.2 Species of National Environmental Significance 57 5.3 Queensland Species of Conservation Significance 65 5.4 Pest Species 68 5.5 Vegetation Communities 70 5.6 Regional Ecosystem Types and Integrity 73 5.7 Aquatic Values 76 5.8 World Heritage and National Heritage Values 95 6. Construction Phase Impacts 97 6.1 Background 97 6.2 Borefield Development Impacts 97 6.3 Social and Planning Construction Phase Impacts 98 6.4 Risk Assessment Matrices 99 7. Operational Phase Impacts 101 7.1 Background 101 7.2 River Processes and Interactions 101 7.3 Cultural/Social Assessment 109 7.4 Habitat Integrity and Availability 112 7.5 Environmental Flows 113 7.6 Flora of Conservation Significance 116 7.7 Fauna of Conservation Significance 119 7.8 Invasive Fauna and Flora Species 123 7.9 Climate Change 127 7.10 Risk Assessment Matrices 127 8. Prudent and Feasible Alternatives 139 8.1 Introduction 139 8.2 Comparative Impacts between Barron River (Lake Placid) Option and Mulgrave River Aquifer Scheme 140 8.3 Environmental Cost Benefit Comparison 152 8.4 “Do Nothing Option” 155 42/15610/99537 Mulgrave River Aquifer Feasibility Study Public Environment Report 9. Proposed Safeguards and Mitigation Measures 156 9.1 Environmental Management Plan 156 9.2 Environmental Triggers and Thresholds for Actions 158 10. Conclusions and Recommendations 162 10.1 Summary of Impacts 162 10.2 Justification for Proposed Action 162 10.3 Compliance with Principles of Ecologically Sustainable Development 163 10.4 Matters of National Environmental Significance 163 10.5 Environmental Acceptability 164 10.6 Technical Feasibility 164 10.7 Compliance with the Objectives of the Environment Protection and Biodiversity Conservation Act 1999 164 11. References 166 Table Index Table 1: Proposed Mitigation Measures for the Mulgrave River Aquifer Scheme vii Table 2 Summary of the Potential Impacts in Relation to Different Climatic Scenarios viii Table 3: Legislative Assessment Requirements 19 Table 4: Summary of NES Matters Protected under Part 3 of the EPBC Act 26 Table 5: Summary of World Heritage Values within/adjacent Aquifer Area of Influence 27 Table 6: Threat Criteria and Consequent Scales 35 Table 7: Likelihood Rating 36 Table 8: Risk Levels and Management Action (example) 37 Table 9: Details of Stakeholders Consulted 38 Table 10: Soil Type and Vertical Conductivity (from DNR, 1999) 44 Table 11: CSIRO Description of Soils in the study area 45 Table 12: Stratigraphic Units (after Muller 1975) 49 Table 13: Major Hydrogeological Units 51 Table 14 Population projections, medium growth – Population and Housing Fact Sheet – August 2009 – Department of Infrastructure and planning 54 42/15610/99537 Mulgrave River Aquifer Feasibility Study Public Environment Report Table 15: Tenure/Landuse in Proposed Infrastructure Areas 56 Table 16: Species of NES Identified as Occurring within the study area 58 Table 17: Summary of Regional Ecosystems and Groundwater Dependencies 71 Table 18: Freshwater Fish Species in the Mulgrave River 81 Table 19: Estuarine Fish Species in the Mulgrave River 92 Table 20: CRCWW, Summary Construction Risk Assessment, Mulgrave River Aquifer 100 Table 21: Summary of Potential Landuse Impacts 110 Table 22: Environmental Flow Calculations 115 Table 23: Summary of Potential Impacts on Threatened Flora Species/Ecological Communities 118 Table 24: Summary of Potential Impacts on Fauna of Conservation Significance 121 Table 25: Summary of Potential Impacts on Threatened Fauna Species 121 Table 26: Summary of Potential Impacts on Migratory Species or its Habitat 122 Table 27: Environmental Risk Assessment Matrix 128 Table 28: Social/Cultural Environmental Risk Assessment 135 Table 29: Risk Assessment Matrix for Numerically Modelled Groundwater Potential Impacts 137 Table 30: CRCWW, Summary Construction Risk Assessment, Mulgrave River Aquifer 142 Table 31: CRCWW, Summary Operational Risk Assessment, Mulgrave River Aquifer 143 Table 32: CRCWW, Summary Construction Risk Assessment, Lake Placid Scheme 144 Table 33: CRCWW, Summary Operational Risk Assessment, Lake Placid Scheme 146 Table 34: Infrastructure Construction/Maintenance Cost/Benefit Comparison 148 Table 35: Operational Cost/Benefit Comparison 150 Table 36: Environmental Cost/Benefit Comparison between Lake Placid and Mulgrave River Aquifer Scheme 153 Table 37: EMP Structure 157 Table 38: Environmental Values 158 42/15610/99537 Mulgrave River Aquifer Feasibility Study Public Environment Report Figure Index Figure 1: General Aquifer Study Area and Locality 9 Figure 2: Aquifer Testing Areas 12 Figure 3: Proposed Borefield Layout 13 Figure 4: Example of Production Bore Construction 14 Figure 5: PER study area and WHA Boundary 25 Figure 6: Topography and Surface Drainage Features 42 Figure 7: CSIRO Soil Mapping Units 47 Figure 8: Soil Associations and Potential Acid Sulfate Soils Areas 48 Figure 9: Geological Units in the study area 50 Figure 10: Regional Ecosystem Conservation Status and Protected Species Observations 67 Figure 11: Vegetation Communities and Groundwater Dependencies 75 Figure 12: Groundwater Flow Directions 103 Figure 13: Mulgrave River Valley 104 Figure 14: Wet Season: River to Aquifer Interactions 105 Figure 15: Dry Season Interactions and Drawdown 106 Figure 16: Mapped Extent of Pond Apple (WTMA 2004) 126 Appendices A Guidelines for the Content of a Draft Public Environment Report B Cairns Regional Council General Policy 1:04:43 C Draft Environmental Management Plan D Numerical Groundwater Modelling Technical Report E Hydrogeology Report F Flora and Fauna Survey Report G Responses to Draft PER H General PER Information 42/15610/99537 Mulgrave River Aquifer Feasibility Study Public Environment Report Executive Summary The Mulgrave River aquifer is currently the subject of a feasibility study as a supplementary urban water supply to Cairns City. As part of this study Cairns Regional Council Water and Waste have submitted the project to the Commonwealth for determination as to whether the project constitutes a “controlled action” under the provisions of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The Commonwealth’s response is that there is potential for the project to impact on matters of National Environmental Significance (NES) (as defined by the EPBC Act), and that further information on the potential impacts of the project on matters of NES are to be submitted to the Commonwealth before a final decision can be reached. These further studies requested by the Commonwealth are to be commensurate with the Public Environment Report guidelines for the project issued to Cairns Regional Council Water and Waste (see Appendix A). This report conforms to the Commonwealth’s requirements for a Public Environment Report (PER) as necessary so that further information can be supplied to the Commonwealth. The primary objects of this PER are: 1. to present the necessary information requested by the Commonwealth in the format as prescribed under the guidelines for a Public Environment Report; 2. to present information on the likely impact of the project on matters of NES to Cairns Regional Council Water and Waste to assist in their deliberations of the environmental feasibility of the project. The Proposed Action The proposed action is the construction and operation of a borefield within an area of alluvium comprising part of the Mulgrave River aquifer. The borefield is designed to abstract up to 15 ML/day from up to ten bores, located in a general area between the Bruce Highway and the Mulgrave River, south of the small township of Aloomba (see Figure 1 for the study area). Each bore is to have an electric submersible pump and a connecting powerline that will form part of an underground pipe network alongside existing rural roads. This pipe network will ultimately connect into the Behana Creek water supply pipeline that exists adjacent to the project area. The only visible expression of the bores will be small security housing over each bore (approximately 2m by 3m) with a connecting powerline from the existing power grid. The borefield is designed as a supplementary water supply to service the south of Cairns. It will be operated on an “as needs” requirement, only when other existing water supplies reach their allocated limits. On this basis, given the monsoonal conditions of the Wet Tropics, the borefield may not operate (under normal climatic conditions) for up to three months in the wet season of January to March (inclusive). For periods outside the wet season, abstraction will be determined by a combination of population demand for water, allocation from existing water sources, and environmental triggers for abstraction thresholds.