LIVING LAKES FEASIBILITY STUDY ENVIRONMENTAL REPORT July 9 2012 prepared for JDA Consultant Hydrologists on behalf of Department of Regional Development and Lands by Land Assessment Pty Ltd and Woodgis Environmental Consultants i CONTENTS ACKNOWLEDGEMENTS .......................................................................................................................... vi ACRONYMS ........................................................................................................................................... vii EXECUTIVE SUMMARY ............................................................................................................................ 1 1. INTRODUCTION ............................................................................................................................... 2 1.1. Background ............................................................................................................................. 2 1.2. Current Condition of the Lakes ............................................................................................... 4 1.3. Objectives................................................................................................................................ 5 2. ASSESSMENT FRAMEWORK ............................................................................................................ 6 2.1. Characterisation and Significance of Environmental Assets ................................................... 6 2.1.1. Wetlands ............................................................................................................................. 6 2.1.2. Vegetation ........................................................................................................................... 7 2.1.3. Flora and Fauna ................................................................................................................... 9 2.2. Potential Impacts and Approvals Processes ......................................................................... 10 2.2.1. Changes in Water Regime ................................................................................................. 10 2.2.2. Changes in Water Salinity ................................................................................................. 11 2.2.3. Impacts on Vegetation, Flora and Fauna .......................................................................... 12 2.2.4. Effects on Lake Ecology ..................................................................................................... 13 2.2.5. Drainage ............................................................................................................................ 14 2.2.6. Lake-bed Dredging ............................................................................................................ 14 2.2.7. Native Title and Aboriginal Heritage ................................................................................. 15 2.2.8. Governance and On-going Management Considerations ................................................ 16 3. LAKE TOWERRINNING ................................................................................................................... 17 3.1. Lake Values and Catchment Context .................................................................................... 17 3.2. Landforms and Soils .............................................................................................................. 20 3.2.1. Overview ........................................................................................................................... 20 3.2.2. Site Survey and Mapping Results ...................................................................................... 22 3.3. Vegetation, Flora and Fauna ................................................................................................. 26 3.3.1. Overview ........................................................................................................................... 26 3.3.2. Site Survey and Mapping Results ...................................................................................... 31 3.3.3. Factoring Influencing Approvals ....................................................................................... 36 3.4. Aboriginal Heritage ............................................................................................................... 37 3.5. Existing Lake Modifications and Initiatives ........................................................................... 38 3.6. Living Lake Enhancements – Environmental Considerations ............................................... 39 3.6.1. ET1: Increase Re-diversion Capacity (Extra Culvert) ......................................................... 39 ii 3.6.2. ET2: Capercup Reserve Drain To Lake ............................................................................... 40 3.6.3. ET3: Dredging of Lake (increased depth) .......................................................................... 41 3.6.4. ET4: Groundwater Replenishment .................................................................................... 41 3.6.5. ET5: Rehabilitation Re-diversion Drain ............................................................................. 42 3.6.6. ET6: Refine Drainage from Outlet Swamp to Arthur River ............................................... 43 3.6.7. ET7: Modify Outlet Structure from Lake to Outlet Swamp .............................................. 44 4. LAKE EWLYAMARTUP .................................................................................................................... 45 4.1. Lake Values and Catchment Context .................................................................................... 45 4.2. Landforms and Soils .............................................................................................................. 47 4.2.1. Overview ........................................................................................................................... 47 4.2.2. Site Survey and Mapping Results ...................................................................................... 50 4.3. Vegetation, Flora and Fauna ................................................................................................. 53 4.3.1. Overview ........................................................................................................................... 53 4.3.2. Site Survey and Mapping Results ...................................................................................... 57 4.3.3. Factoring Influencing Approvals ....................................................................................... 62 4.4. Aboriginal Heritage ............................................................................................................... 62 4.5. Existing Lake Modifications and Initiatives ........................................................................... 65 4.6. Living Lake Enhancements – Environmental Considerations ............................................... 66 4.6.1. EE1: Diversion ................................................................................................................... 66 4.6.2. EE2: Flushing ..................................................................................................................... 67 4.6.3. EE3: Dredging of Lake (increased depth) .......................................................................... 68 4.6.4. EE4: Groundwater Replenishment .................................................................................... 69 4.6.5. EE5: LEWG Option G32 ..................................................................................................... 70 4.6.6. EE6: LEWG Option G41 ..................................................................................................... 70 5. LAKE YEALERING............................................................................................................................ 71 5.1. Lake Values and Catchment Context .................................................................................... 71 5.2. Landforms and Soils .............................................................................................................. 74 5.2.1. Overview ........................................................................................................................... 74 5.2.2. Site Survey and Mapping Results ...................................................................................... 77 5.3. Vegetation, Flora and Fauna ................................................................................................. 80 5.3.1. Overview ........................................................................................................................... 80 5.3.2. Site Survey and Mapping Results ...................................................................................... 83 5.3.3. Factoring Influencing Approvals ....................................................................................... 87 5.4. Aboriginal Heritage ............................................................................................................... 88 5.5. Existing Lake Modifications and Initiatives ........................................................................... 89 5.6. Living Lake Enhancements – Environmental Considerations ............................................... 90 5.6.1. EY1: Bund within Backswamps ........................................................................................