COCKBURN SOUND MANAGEMENT COUNCIL THE STATE OF COCKBURN SOUND: A PRESSURE-STATE-RESPONSE REPORT Prepared for: COCKBURN SOUND MANAGEMENT COUNCIL Prepared by: D.A. LORD & ASSOCIATES PTY LTD In association with: PPK ENVIRONMENT AND INFRASTRUCTURE PTY LTD JUNE 2001 REPORT NO. 01/187/1 CONTENTS EXECUTIVE SUMMARY __________________________________________________ v 1. INTRODUCTION ________________________________________________________ 1 1.1 BACKGROUND ___________________________________________________________________ 1 1.2 ENVIRONMENTAL HISTORY OF COCKBURN SOUND _________________________________ 2 1.3 ENVIRONMENTAL MANAGEMENT APPROACH FOR COCKBURN SOUND _______________ 5 1.4 THIS DOCUMENT _________________________________________________________________ 7 2. MARINE COMPONENT __________________________________________________ 9 2.1 REGIONAL CONTEXT _____________________________________________________________ 9 2.2 ECOSYSTEM OVERVIEW __________________________________________________________ 9 2.3 STATE OF THE MARINE ENVIRONMENT ___________________________________________ 10 2.3.1 Water movement in the Sound ____________________________________________________ 10 2.3.2 Coastal processes _____________________________________________________________ 18 2.3.3 Water quality _________________________________________________________________ 22 2.3.4 Marine sediments______________________________________________________________ 29 2.3.5 Marine flora__________________________________________________________________ 32 2.3.6 Marine fauna _________________________________________________________________ 40 2.4 PRESSURES ON THE MARINE ENVIRONMENT ______________________________________ 43 2.4.1 Ecosystem overview____________________________________________________________ 43 2.4.2 Physical alterations to the environment ____________________________________________ 44 2.4.3 Nutrient enrichment____________________________________________________________ 44 2.4.4 Contaminants_________________________________________________________________ 47 2.4.5 Cooling waters________________________________________________________________ 48 2.4.6 Foreign marine organisms_______________________________________________________ 48 2.4.7 Commercial and recreational fishing ______________________________________________ 49 2.5 MANAGEMENT RESPONSES ______________________________________________________ 51 2.5.1 Current management responses___________________________________________________ 51 2.5.2 Gaps in the management responses________________________________________________ 52 2.5.3 Gaps in information needed for management ________________________________________ 53 3. LAND COMPONENT ___________________________________________________ 61 3.1 OVERVIEW______________________________________________________________________ 61 3.2 THE LAND AND ITS USES_________________________________________________________ 61 3.2.1 Coastal fringe landform_________________________________________________________ 61 3.2.2 Groundwater aquifers __________________________________________________________ 61 3.2.3 Coastal flora and fauna_________________________________________________________ 62 3.2.4 Land uses____________________________________________________________________ 64 3.3 PRESSURES ON COCKBURN SOUND DUE TO LAND USE _____________________________ 68 3.3.1 Contaminants from different land uses _____________________________________________ 68 3.3.2 Contamination of groundwater ___________________________________________________ 69 3.3.3 Contaminant inputs due to surface waters and atmospheric fallout _______________________ 70 3.4 ENVIRONMENTAL MANAGEMENT OF LAND USE ___________________________________ 71 3.4.1 Current management responses___________________________________________________ 71 3.4.2 Gaps in the management responses________________________________________________ 72 3.4.3 Gaps in information needed for management ________________________________________ 72 4. SOCIAL AND CULTURAL COMPONENT _________________________________ 73 4.1 OVERVIEW______________________________________________________________________ 73 4.2 SOCIAL AND CULTURAL USES OF COCKBURN SOUND AND ITS FORESHORE__________ 73 4.2.1 Existing and potential social uses _________________________________________________ 73 4.2.2 Aesthetics/seascapes ___________________________________________________________ 79 4.2.3 Heritage_____________________________________________________________________ 79 4.3 PRESSURES ON COCKBURN SOUND DUE TO SOCIAL AND CULTURAL USES __________ 80 4.3.1 Existing and potential uses ______________________________________________________ 80 4.3.2 Aesthetics/seascapes ___________________________________________________________ 81 4.3.3 Heritage_____________________________________________________________________ 81 4.4 ENVIRONMENTAL MANAGEMENT OF SOCIAL AND CULTURAL USES ________________ 81 4.4.1 Current management responses___________________________________________________ 81 4.4.2 Gaps in the management responses________________________________________________ 82 4.4.3 Gaps in information needed for management ________________________________________ 83 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE i 5. ECONOMIC COMPONENT______________________________________________ 85 5.1 OVERVIEW______________________________________________________________________ 85 5.2 ECONOMIC USES OF COCKBURN SOUND __________________________________________ 85 5.2.1 Industry _____________________________________________________________________ 85 5.2.2 Shipping (Commercial and Defence)_______________________________________________ 85 5.2.3 Commercial fishing ____________________________________________________________ 89 5.2.4 Aquaculture __________________________________________________________________ 90 5.2.5 Tourism _____________________________________________________________________ 90 5.3 PRESSURES ON COCKBURN SOUND DUE TO ECONOMIC USES _______________________ 91 5.3.1 Industry _____________________________________________________________________ 91 5.3.2 Shipping_____________________________________________________________________ 91 5.3.3 Commercial fishing ____________________________________________________________ 92 5.3.4 Aquaculture __________________________________________________________________ 93 5.3.5 Tourism _____________________________________________________________________ 93 5.4 ENVIRONMENTAL MANAGEMENT OF ECONOMIC USES_____________________________ 93 5.4.1 Current management responses___________________________________________________ 93 5.4.2 Gaps in the management responses________________________________________________ 96 5.4.3 Gaps in information needed for management ________________________________________ 97 6. RECOMMENDED RESEARCH AND INVESTIGATION PROGRAMME _______ 99 6.1 MARINE ________________________________________________________________________ 99 6.2 LAND___________________________________________________________________________ 99 6.3 SOCIAL AND CULTURAL ________________________________________________________ 100 7. REFERENCES AND FURTHER RECOMMENDED READING ______________ 101 8. ACKNOWLEDGMENTS________________________________________________ 113 9. GLOSSARY ___________________________________________________________ 115 10. ABBREVIATIONS__________________________________________________ 117 ii COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE TABLES Table 1.1 Relationship between Environmental Values and Environmental Quality Objectives _____________________________________________________ 6 Table 2.1 Flushing times for Cockburn Sound ________________________________ 18 Table 2.2 Average chlorophyll levels at various sites in Cockburn Sound, summer 2000/2001 ____________________________________________________ 25 Table 2.3 Changes in nitrogen concentrations in Cockburn Sound sediments ________ 30 Table 2.4 Sediment contaminant levels in 1994 sediment survey (DEP, 1996) and 1999 sediment survey (DAL, 2000)_________________________________ 31 Table 2.5 Estimated changes in plant production in Cockburn Sound since the 1950s ________________________________________________________ 37 Table 2.6 Estimated changes in nitrogen used by plants in Cockburn Sound since the 1950s _____________________________________________________ 38 Table 2.7 Summary of emergency overflows from the Woodman Point Wastewater Treatment Plant to Cockburn Sound since 1990 _______________________ 45 Table 2.8 Estimated contaminant inputs from licensed industrial discharges to Cockburn Sound________________________________________________ 47 Table 2.9 Potential framework for cumulative impact assessment strategy __________ 59 Table 3.1 Estimated loads of nitrogen in groundwater discharged to Cockburn Sound ________________________________________________________ 70 Table 4.1 Recreational fishing effort in the Cockburn Sound/Owen Anchorage region, 1996/97 ________________________________________________ 73 Table 4.2 Estimated boat use at public boat ramps _____________________________ 79 Table 5.1 Ship arrivals to Cockburn Sound (FPA outer harbour) in 2000 ___________ 85 Table 5.2 Operators and cargo handled at commercial jetties in Cockburn Sound _____ 88 Table 5.3 Details of commercial fisheries operating in Cockburn Sound Fisheries Block 9600 ____________________________________________________ 89 Table 5.4 Licensed industrial discharges to Cockburn Sound _____________________ 91 FIGURES Figure 1.1 Cockburn Sound_________________________________________________