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Department of Agriculture, Fisheries & Forestry ASSESSMENT OF RISK OF SPREAD FOR STRATEGIC MANAGEMENT OF THE CORE ALLIGATOR WEED INFESTATIONS IN AUSTRALIA - TAKING STOCK FINAL REPORT October 2008 Department of Agriculture, Fisheries and Forestry Assessment of Risk of Spread for Strategic Management of the Core Alligator Weed Infestations in Australia- ‘Taking Stock’ CERTIFICATE OF APPROVAL FOR ISSUE OF DOCUMENTS Report Title: Final Report Document Status: Final Report Document No: NE210541-2008 Date of Issue: 10/10/2008 Assessment of Risk of Spread for Strategic Management Client: Department of Agriculture, Project Title: of the Core Alligator Weed Infestations in Australia - Fisheries & Forestry Taking Stock Comments: Position Name Signature Date Prepared by: Principal Consultant Dr. Nimal Chandrasena 10 October 2008 DAFF, CMAs, DPI, Peer Review by: LGAs and various Given in acknowledgements July-August 2008 others For further information on this report, contact: Name: Dr. Nimal Chandrasena Title: Principal Ecologist, Ecowise Environmental Address: 24 Lemko Place, Penrith, NSW 2750 Phone: 4721 3477 Mobile: 0408 279 604 E-mail: [email protected] Document Revision Control Version Description of Revision Person Making Issue Date Approval 1 Working Draft Dr. Nimal Chandrasena 27 July 2008 2 Final Draft Dr. Nimal Chandrasena 10 October 2008 © Ecowise Environmental Pty Ltd This Report and the information, ideas, concepts, methodologies, technologies and other material remain the intellectual property of Ecowise Environmental Pty Ltd. Disclaimer This document has been prepared for the Client named above and is to be used only for the purposes for which it was commissioned. No warranty is given as to its suitability for any other purpose. Ecowise Environmental Pty Ltd ABN 68 074 205 780 Ecowise Environmental (Victoria) Pty Ltd ABN 94 105 060 320 Enviro-Managers Pty Ltd ABN 18 072 428 810 Final Report ii Department of Agriculture, Fisheries and Forestry Assessment of Risk of Spread for Strategic Management of the Core Alligator Weed Infestations in Australia- ‘Taking Stock’ Final Report In relation to Financial Assistance for the Activity ID 64331 Risk Assessment for Strategic Management of the Core Alligator Weed Infestation in Australia - Taking Stock COMMONWEALTH OF AUSTRALIA As represented by the Department of Agriculture Fisheries and Forestry (DAFF) ABN 24 113 085 695 Prepared by: Dr. Nimal Chandrasena Principal Ecologist Ecowise Environmental (Vic) Pty Ltd For DAFF and Gutteridge Haskins & Davey Pty Ltd ABN 39 008 488 373 Final Report iii Department of Agriculture, Fisheries and Forestry Assessment of Risk of Spread for Strategic Management of the Core Alligator Weed Infestations in Australia- ‘Taking Stock’ TABLE OF CONTENTS Executive Summary vi Acknowledgements x 1 Introduction 11 1.1 Background 11 1.2 Context of the Study 13 1.3 Recent research and management efforts 14 1.4 Scope of the Project and Report 15 2 Study Methods 16 2.1 Locations and Site Visits 16 2.2 Information Review and Consultations 16 2.3 Risk Factors 17 2.4 Risk Assessment Method 23 3 Results and Discussion 25 3.1 Sydney Region 25 3.1.1 Sydney West/Blue Mountains Region 27 3.1.2 South-West Sydney Region 30 3.1.3 Sydney Central Region 34 3.1.4 Sydney North Region 35 3.2 Hunter Region 35 3.2.1 Cessnock LGA 35 3.2.2 Gosford LGA 37 3.2.3 Lake Macquarie LGA 37 3.2.4 Newcastle City LGA 38 3.2.5 Port Stephens LGA 39 3.2.6 Maitland LGA 40 3.2.7 Singleton LGA 41 3.3 Managing Vectors of Spread 42 3.3.1 Floods, Recreational Activities and Irrigation- 42 3.3.2 Earth Moving Activities and Machinery- 42 3.3.3 Commercial Activities including Aquatic Weed Harvesting 43 3.3.4 Soil/Waste Dumping, Landscaping and Maintenance Activities 43 3.3.5 Floodplain Agriculture 43 3.3.6 Catchment-location and Critical Sites 43 3.3.7 Size of Infestations 44 3.3.8 Management Protocols to prevent the spread of Alligator Weed 44 4 Conclusions 45 5 References 52 Final Report iv Department of Agriculture, Fisheries and Forestry Assessment of Risk of Spread for Strategic Management of the Core Alligator Weed Infestations in Australia- ‘Taking Stock’ List of Figures Figure 1. Areas with climate suitability for Alligator Weed establishment. ..............................................12 Figure 2. Declaration of Alligator Weed in NSW by region .....................................................................12 Figure 3. Alligator Weed Infestations- Sydney Basin..............................................................................26 Figure 4. Alligator Weed Infestations- Hunter Region.............................................................................36 List of Tables Table 1. Current Declaration of Alligator Weed by Local Government Area...........................................13 Table 2. Known Vectors of spread for Alligator Weed and associated risk level ....................................17 Table 3. Risk of Floods...........................................................................................................................18 Table 4. Risk of Recreational Activities...................................................................................................19 Table 5. Risk of Earth Moving Activities..................................................................................................19 Table 6. Risk of Irrigation Activities.........................................................................................................20 Table 7. Risk of Commercial Activities....................................................................................................20 Table 8. Risk of Soil, Waste Dumping ....................................................................................................21 Table 9. Risk of Landscaping Activities ..................................................................................................21 Table 10. Risk of Floodplain Agriculture .................................................................................................21 Table 11. Risk of Infestation location in Catchment and/or ‘Critical Sites’ ..............................................22 Table 12. Risk of Size of Infestations......................................................................................................23 Table 13. Risk Framework used in the risk assessment.........................................................................24 List of Plates Plate 1. A close-up view of Alligator Weed, showing growth habit..........................................................11 Plate 2. Alligator Weed forming extensive mats over water in infested waterways.................................11 Plate 3. A large Alligator Weed infestation in Smalls Creek, Sydney......................................................11 Plate 4. Alligator Weed infesting flood-prone paddocks in Williamtown, Port Stephens (Photo: Graham Prichard) ........................................................................................................11 Plate 5. Heavy Alligator Weed infestations in Devlin and Shaws Lakes, Hawkesbury River, (Photo- Rebecca Coventry)......................................................................................................18 Plate 6. Alligator Weed infested drain in Williamtown, Port Stephens Council, Hunter; (Photo- Rebecca Coventry)......................................................................................................18 Plate 7. Earth moving equipment represents a considerable risk for spread of Alligator Weed (Photo- Brain Worboys)..................................................................................................19 Plate 8. Workers cleaning machinery before transport from a site (Photo- Brain Worboys) ...................19 Plate 9. Contaminated Mulch as a source of Alligator Weed (Photo- Rebecca Coventry)......................22 Plate 10. Stock feeding on Alligator Weed (Photo- Graham Prichard) ...................................................22 Plate 11. Botany Wetlands, Mill Pond (Upstream) with heavy infestations of Alligator Weed.................23 Plate 12. Habit of Terrestrial Alligator Weed...........................................................................................23 List of Appendices Appendix A – Risk Assessments- Sydney Basin ....................................................................................54 Appendix B – Risk Assessments- Hunter Region.................................................................................107 Final Report v Department of Agriculture, Fisheries and Forestry Assessment of Risk of Spread for Strategic Management of the Core Alligator Weed Infestations in Australia- ‘Taking Stock’ Executive Summary Alligator Weed is acknowledged as an aquatic invader that poses possibly the largest threat to Australian waterways and moist, terrestrial landscapes. Since the threat became evident in the late 1980s, control efforts to manage Alligator Weed using an integrated approach have been continuing. Despite considerable efforts, Alligator Weed has expanded its range across NSW, and is now present in Queensland, Act and Victoria. Ineffective and inconsistent treatment programmes and a variety of other factors have contributed to its spread, far and widely, across the Hunter Region and Sydney Basin in Eastern Australia. These two regions, with deeply entrenched and historical infestations, are regarded as ‘core’ infestation areas. Funded by the Commonwealth’s ‘Defeating The Weed Menace Programme’