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______3 Figure 1.2 The Pressure-State-Response model ______7 Figure 2.1 Wave height in Cockburn Sound during a severe storm with westerly winds ______11 Figure 2.2 Surface circulation patterns during summer (left) and winter (right) ______13 Figure 2.3 Depth-averaged currents during summer in Cockburn Sound and surrounds ______13 Figure 2.4 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative of summer ____ 16 Figure 2.5 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative of autumn_____ 16

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE iii Figure 2.6 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative winter-spring __ 17 Figure 2.7 Shoreline movement in Mangles Bay from DMH (1992) ______21 Figure 2.8 Summer water quality monitoring sites in Cockburn Sound ______22 Figure 2.9 Summer chlorophyll levels in Cockburn Sound versus summer nitrogen inputs from human activities (outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) ____ 23 Figure 2.10 Summer chlorophyll levels in Cockburn Sound versus summer nitrogen inputs from human activities (outfall discharges excluding the Woodman Point WWTP outfall; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) ______24 Figure 2.11 Summer water quality at Cockburn Sound sites 6, 8, 9 and 10, versus summer nitrogen inputs from human activities (outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) ______26 Figure 2.12 Estimated nitrogen inputs from sediments and human activities in 1978, and amount of nitrogen required by phytoplankton and MPB ______28 Figure 2.13 Estimated nitrogen inputs from sediments and human activities in 2000, and amount of nitrogen required by phytoplankton and MPB ______28 Figure 2.14 Benthic habitats in Cockburn Sound ______33 Figure 2.15 Historical sequence of seagrass dieback in Cockburn Sound ______35 Figure 2.16 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 1950 ______39 Figure 2.17 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 1978 ______39 Figure 2.18 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 2000 ______40 Figure 2.19 Estimated nutrient inputs to Cockburn Sound from outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading in 1978, 1990 and 2000 ______46 Figure 2.20 Annual commercial fish catches in Cockburn Sound Fisheries Block 9600 since 1977 (excludes mussels from aquaculture) ______50 Figure 3.1 Land uses in Cockburn Sound’s catchment ______65 Figure 4.1 Social and cultural uses of Cockburn Sound ______74 Figure 4.2 Peak recreational use in Owen Anchorage during snap-shot survey______78 Figure 5.1 Economic uses of Cockburn Sound ______86 Figure 5.2 Types of commodities handled by the FPA______88

APPENDICES

Appendix A Estimation of nutrient pools and nutrient turnover in Cockburn Sound ____ 121 Appendix B Estimation of nutrient and contaminant inputs into Cockburn Sound______125

iv COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE EXECUTIVE SUMMARY Cockburn Sound is the most intensively used marine embayment in Western Australia. Its deep, sheltered waters are extremely popular for fishing and recreation, and it is also the site of a busy port, an industrial area that depends on port facilities, and a strategic naval base. These multiple uses demand careful environmental management and planning, especially as all types of use are expected to intensify.

The Cockburn Sound Management Council (CSMC) is currently preparing an Environmental Management Plan (EMP) to coordinate environmental management and planning for the Sound and its catchment. The EMP needs to be based on up-to-date information on the environmental state of the Sound, the pressures on it, and the management responses in place to manage those pressures. This document is a Pressure-State Response (P-S-R) report prepared to provide that information. The report follows the proposed EMP structure of four components: marine, land, social/cultural and economic. Key gaps in management responses and information that are making management more difficult have also been identified, and a research programme recommended to address information gaps.

MARINE COMPONENT Studies in the late 1970s found that industrial discharge into Cockburn Sound had caused widespread contamination of sediments and biota, poor water quality and widespread loss of seagrass on the eastern margin of the Sound. The loss of seagrass was attributed to light starvation due, in turn, to shading caused by nutrient-stimulated growth of epiphytes (algae that grow on seagrass leaves) and phytoplankton (microscopic algae in the water). The two main sources of nutrients were pipeline discharges: the KNC/CSBP outfall, and the Water Authority’s Woodman Point wastewater treatment plant outfall.

In the early 1990s, the Southern Metropolitan Coastal Water Study (SMCWS) found that seagrass dieback had slowed considerably, but nutrient-related water quality was only slightly better than in the late 1970s. Contaminated groundwater had replaced industrial discharge as the main nitrogen input to the Sound, and came mainly from two short areas of coastline: the southern part of the Kwinana Industrial Area; and in the Jervoise Bay Northern Harbour. Industrial discharge of metals and organic contaminants (e.g. pesticides and petroleum products) had decreased substantially, as had contamination of sediments and biota. There was, however, widespread contamination of sediments and mussels with tributyltin (TBT, a highly toxic ingredient in antifoulant paints commonly applied to boats), with particularly high levels near harbours, marinas and commercial and naval wharves. The introduction of foreign marine organisms via shipping activities (ballast discharge, hull fouling) was also raised as a concern.

Work undertaken since the early 1990s has found no further deterioration of the health of surviving seagrass meadows, and no significant losses related to water quality. Overall water quality has improved slightly since the early 1990s, apart from in the Jervoise Bay Northern Harbour. Nutrient inputs from human activities have declined from a estimated 2000 tonnes/year in 1978 to about 300 tonnes/year in 2000, about 70% of which is from groundwater. The three main areas from which nutrient-rich groundwater is coming are: the southern part of the Kwinana Industrial Area (74 tonnes/year); the Jervoise Bay Northern Harbour (66 tonnes/year); and rural areas (46 tonnes/year).

Estimated amounts of metals and oil discharged by industry have continued to decrease due to improved waste treatment practices, and are presently about one sixth to one thousandth of those discharged in 1978, depending on the contaminant in question. A 1999 sediment survey found that contaminant levels (including arsenic and mercury) were well below environmental guidelines, apart from TBT in some areas. TBT levels in sediments were generally lower than in 1994, but still high in the Jervoise Bay Northern Harbour and adjacent to naval facilities in Careening Bay. A survey in 1999 also confirmed the presence of two acknowledged foreign marine pests in the Sound: the European fan worm Sabella cf. Spallanzanii, and the Asian date mussel Musculista senhousia. These two pests are prolific growers and can out compete native species, affecting biodiversity, but this does not seem to be occurring in Cockburn Sound.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE v Nutrient-related water quality remains one of the two main environmental concerns in Cockburn Sound, and there have been concerted efforts by industry to reduce nitrogen inputs from groundwater. WMC’s Kwinana Nickel Refinery has reduced nitrogen discharges from about 500 tonnes/year in 1990 to 8 tonnes/year; there has been a 14% improvement at the Wesfarmers CSBP site in the four years to 2000, and inputs to the Jervoise Bay Northern Harbour are expected to decrease from 66 tonnes/year to 26 tonnes/year within a year.

Nutrient-related water quality has been monitored by means of summer surveys of chlorophyll levels (an accepted measure of phytoplankton growth) since 1977. There have been large decreases in nitrogen inputs to the Sound during summer, but this has not been matched by a similar decrease in chlorophyll levels. Up to 1990, the largest nutrient input to Sound was a ‘point’ source (the KNC/CSBP outfall) that was clearly related to overall chlorophyll levels in the Sound. Now chlorophyll levels are mainly determined by sediment nutrient cycling and diffuse nutrient inputs (groundwater), and the relationship between nutrient inputs from human activities and chlorophyll levels is less direct. With the present level of understanding, it is not possible to predict to what extent further reductions in diffuse nutrient inputs from human activities will reduce overall chlorophyll levels in the Sound, and available data indicate any response is likely to be slow. Further reductions in diffuse nutrient inputs should, however, result in localised improvements in water quality.

The other main environmental concern in Cockburn Sound is TBT contamination, and a number of management measures address this. The WA State Government has banned the use of TBT on vessels less than 25 m long, and restricted its use to low-leaching paints on boats over 25 m. The Royal Australian Navy has banned TBT use on ships less than 40 m in length, and is replacing TBT on larger warships with a copper-based paint. The Fremantle Port Authority has banned ‘in-water’ hull cleaning when ships are at berth (believed to be a major contributor of TBT to sediments). Insofar as international shipping is concerned, the International Maritime Organization has recently announced that it will ban application of TBT to ship’s hulls from January 2003. These measures are expected to produce significant decreases in TBT contamination due to shipping movements. The high levels of TBT in Cockburn Sound sediments at present appear to be more related to shipping maintenance areas than shipping movements, and forthcoming bans on the use of TBT should reduce inputs from these areas too.

LAND COMPONENT Land uses within the Cockburn Sound catchment includes urban areas, defence, industry, agriculture and conservation. Expansions in urban areas, defence and industrial land use are either planned or expected, while rural areas are being encroached by urban and industrial use. Coastal areas reserved for conservation include Woodman Point Regional Park, Beeliar Regional Park and Rockingham Lakes Regional Park, and their boundaries are unlikely to change.

A population increase of 30% is expected in mainland urban areas in next 10 years, and a 25% increase in personnel and ships on Garden Island by 2004 (as part of the ‘Two Oceans’ defence policy). For industrial use, there is the proposed development of 800 hectares of general light industrial land over the existing townsite of Wattleup, and the extension of heavy industry into 100 hectares of land in the Hope Valley area. The marine construction and maintenance industry is also expanding in the Henderson shipbuilding area, and there is the proposed East Rockingham Industrial Park (IP14) between Mandurah and Patterson Roads.

The main way that land uses affect the environment of Cockburn Sound is by contamination of groundwater and surface water that flows into the Sound. At present, nutrient inputs to the Sound are largely from groundwater contaminated by industry, but as noted earlier, these are decreasing and the relative role of rural areas is starting to become significant. There is less information on other groundwater contaminants such as metals and organic compounds, but indications are that this kind of contamination does not migrate as far from its source as nutrient contamination, and so is less likely to be discharged into the Sound.

SOCIAL AND CULTURAL COMPONENT Cockburn Sound is extremely popular for recreational fishing, water sports (swimming, boating, yachting, diving, windsurfing, skiing) and beach use. It is also important for the social values of vi COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE aesthetics, maritime heritage (its association with early settlement in WA and the presence of four historic wreck sites) and indigenous heritage (notably Aboriginal mythology about the creation of Garden and Rottnest Islands).

Cockburn Sound is particularly popular for family/small boat use, due to its sheltered nature. For boat-based recreational fishing within coastal waters from Augusta to Kalbarri, the Sound is second in importance only to the Hillarys area. A 1999 survey of public boat ramps estimated that 44,270 boats were launched in Cockburn Sound, and this is predicted to increase by 75% in the next 20 years.

Coastal access between the CBH jetty and Woodman Point is becoming increasingly restricted due to industrial development. Coastal access has emerged as a key issue during preparation of this report. Community concerns have been expressed that, with population increases, more people will want beach access, while less and less beach is becoming available. There is the potential for intense recreational pressure at the Woodman Point and the Rockingham foreshore.

Management of coastal recreational activities focuses on zoning to separate incompatible uses, ensuring suitable facilities (rubbish bins, toilets) are available and providing suitable paths and/or barriers to control erosion. The City of Cockburn, Town of Kwinana and City of Rockingham all have coastal, foreshore and/or recreation management plans in place, all of which are currently being reviewed and that will undergo further review to ensure consistency with the CSMC’s EMP. Recreational fishing is managed by means of licences, bag limits, minimum sizes (e.g. fish length, crab carapace width) and fishing gear controls set by Fisheries WA and enforced by Fisheries Officers. A review of recreational fisheries management arrangements for the west coast is also currently under way.

ECONOMIC COMPONENT Economic uses of Cockburn Sound include industry, shipping (commercial and defence), commercial fishing, aquaculture and tourism.

Cockburn Sound is the outer harbour of the Port of Fremantle, and there were 967 ship arrivals (232 naval vessels) in 2000. In the 1999/2000 year, the Fremantle Port Authority (inner and outer harbour) handled 23.4 million tonnes of commodities (mainly petroleum products, grain and alumina), the large majority in Cockburn Sound. Shipping is closely linked to industry in Cockburn Sound, with industry in the Kwinana Industrial Area alone estimated to produce goods worth at least $6 billion/year.

Commercial fisheries that operate within Cockburn Sound target crabs (estimated value about $1 million/year) table fish (estimated value about $240,000/year) and baitfish (estimated value about $900,000/year, but includes waters outside Cockburn Sound). The mussel aquaculture industry within Cockburn Sound has a dollar value of the same order as the commercial crab catch. Tourism operators ferry about 18,000 people through or into Cockburn Sound each year, grossing about $1.4 million.

The main effects—and management—of industry and shipping on Cockburn Sound were discussed earlier. Commercial fishing and aquaculture in Cockburn Sound are carefully managed activities: the former by controls on access, boat size, catch size, and fishing gear that can be used; and the latter by access, and spacing of aquaculture lines. The charter fishing industry also came under management for fish catches in July 2000, following a major review of charter fishing and associated ecotourism.

KEY GAPS IN MANAGEMENT AND INFORMATION

Management gaps Previous efforts to manage Cockburn Sound have been hampered by lack of a consistent and coordinated management approach across different levels of government, industry and community groups. Two main areas where a coordinated approach is needed are catchment management and resolution of recreational access, as follows:

• Industrial discharge to the Sound has decreased substantially, and groundwater quality below the larger industries is improving. Therefore, the relative contaminant contribution of the more

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE vii diffuse sources throughout the catchment (e.g. rural areas) will increase. In most cases direct intervention of these sources will not be justified, but long-term improvement in groundwater quality throughout the catchment could be addressed (and future groundwater problems avoided) by developing a catchment management plan that involves local councils and major industrial and rural land users/owners; and • The social and cultural use of Cockburn Sound is arguably one of the most sensitive management issues in Cockburn Sound. At present, there is no coordinated management approach examining ways in which the existing coastline—and associated recreational facilities—can be developed/upgraded/re-zoned to best meet present and future recreational needs.

The CSMC provides a mechanism for coordinating environmental management and planning, and has already commenced coordination of the above two activities. There has, however, been some comment on the exclusion of Garden Island from the defined area under the jurisdiction of the CSMC, as it needs to be considered as much as the eastern coastal boundary in any environmental planning and management.

Information gaps Water quality in the Sound is controlled by factors such as water circulation and exchange, water depth and the size, proximity and type (eg. outfall discharge or groundwater) of nitrogen input(s): these factors differ between the shallow regions (i.e. water depths less than 10 m) on the east and west of the Sound, the deep central basin, and the poorly flushed waters of the southern basin, and are pivotal in determining the water quality that can be attained. Environmental decision-making is currently being made more difficult by incomplete understanding of the factors controlling water quality within the Sound, notably the responses to diffuse nutrient inputs and the role of sediment nutrient cycling. This information is also needed to predict the effects of any development proposals that alter circulation and exchange characteristics within and between development area(s). As accurate prediction of circulation and flushing characteristics is needed before water quality can be predicted, there are also increasing demands being made of hydrodynamic models.

There are four main areas where information is needed to improve understanding of nutrient-related water quality:

• Additional data to improve hydrodynamic modelling of Cockburn Sound (this would also improve understanding of coastal processes in the Sound); • An agreed conceptual model of nutrient cycling in Cockburn Sound and the effects of nutrient inputs; • Data on sediment nutrient cycling characteristics; and • An agreed method for evaluating cumulative impacts.

Finally, it is noted that despite the sensitivity surrounding social and cultural uses of Cockburn Sound, it has not been studied as much as environmental issues. The coordinated management and planning of social and cultural uses in the Cockburn Sound is in urgent need of data on the type, location and intensity of recreational uses.

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viii COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 1. INTRODUCTION

1.1 BACKGROUND Coastal areas are favoured sites for concentrated human settlement, especially near rivers. Settlement in Western Australia is typical of this pattern: the metropolitan region of Perth, the capital city, is centred on the Swan/Canning estuary, and about 1.3 million people (over 70% of the State’s population) live in a narrow strip of coast 90 km long and 10–40 km wide. People use this environment to supply and manufacture the goods required for living, to absorb their wastes, and for recreation. This concentrated level of human activity creates pressures on the coastal environment that can cause environmental degradation.

Cockburn Sound, some 20 km south of the Perth-Fremantle area, has two features that are unique along Perth’s metropolitan coast: its degree of shelter from ocean swell, and its depth (Figure 1.1). As a result of these features, it is also the most intensively used marine embayment in Western Australia.

The Sound is 16 km long and 9 km wide, with a 17−22 m deep central basin. Garden Island extends along almost the entire western side of the Sound, providing shelter from ocean swells and making the Sound an ideal place for recreation and fishing. The sheltered, deep waters of the Sound make it equally ideal as an outer harbour for the Perth/Fremantle area, a site for industries requiring port facilities, and a strategic naval base. As a result, Cockburn Sound experiences the combined pressures of fishing, recreation, waste disposal, industry, shipping and naval activities.

The multiple uses of Cockburn Sound demand careful, coordinated environmental planning and management. Lack of such management in the 1960s and 70s resulted in the environmental degradation of the Sound. Management measures in the 1980s and 1990s have improved many aspects of the Sound’s environmental health, but further improvement is needed in some localised areas (e.g. the decline in water quality in the Jervoise Bay Northern Harbour since 1997). Pressure on the Sound is also increasing due to population growth and increasing industrial development, shipping and naval activities.

The Cockburn Sound Management Council (CSMC) is a State Government response to ongoing concerns about existing and future pressures on Cockburn Sound. The CSMC is a Committee of the Board of the Water and Rivers Commission (WRC), and consists of 26 members drawn from a cross-section of state and local government departments, community groups, industry, and commonwealth defence. The first CSMC meeting took place in August 2000.

The CSMC’s main role is to develop an Environmental Management Plan (EMP) that coordinates environmental management and planning for the Sound and its catchment. In an interrelated exercise, the Environmental Protection Authority (EPA) and Department of Environmental Protection (DEP) are developing an Environmental Protection Policy (EPP) for Cockburn Sound, that addresses pollution issues. This EPP will define environmental quality objectives (EQOs) and environmental quality criteria (EQC)—particular aspects of water, sediments and marine organisms (e.g. contaminant levels in water, sediments and fish)—to protect the recognised environmental values of the Sound. A key focus of the CSMC’s EMP will be the development of management strategies to ensure the EQOs and EQC of the EPP are met.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 1 To develop the EMP, information is needed on the present environmental state of the Sound, the pressures on it, and the environmental management responses already in place. The purpose of this report on ‘The State of Cockburn Sound’ is to provide that information, specifically to:

• Provide an up-to-date description of the state of Cockburn Sound and its catchment, the pressures on the resources base, and the current management responses; • Identify the gaps in the current management responses and indicate management strategies to address these gaps; and • Outline a research and investigation program to improve the information and knowledge base for future decision-making.

1.2 ENVIRONMENTAL HISTORY OF COCKBURN SOUND Until 1954 Cockburn Sound was used mainly for recreational purposes, commercial fishing, and—during both World Wars—for Commonwealth defence activities (particularly on Garden Island). There are many anecdotes of the clear waters, plentiful fish and extensive, healthy seagrass meadows along the eastern shores of the Sound during these years (Norm Halse1, pers. com.).

In 1954 industrial development in the Sound commenced with the building of an oil refinery at James Point. The next 25 years saw the addition of iron, steel, alumina and nickel refining/processing plants, chemical and fertiliser production plants and a bulk grain terminal. Wharves and groynes were built and channels dredged for shipping access: the Sound became the ‘outer harbour’ for the Fremantle Port Authority. At the northern end of the Sound, a wastewater treatment plant was commissioned at Woodman Point in 1966 to treat sewage from Perth’s southern suburbs. At the southern end of the Sound, a rockfill causeway connecting Garden Island with the mainland was built between 1971−1973. The causeway is broken by two trestle bridges (one 305 m long, and one 610 m long)2, through which limited ocean exchange occurs. The causeway was built to service a naval base on Garden Island, which was constructed between 1973 and 1978.

The developments that took place from 1954 onwards resulted in deterioration of the environment, and in the 1970s conflict with recreational users became an additional issue. The first environmental studies were carried out in the early 1970s (funded by the Fremantle Port Authority) and identified two major environmental problems:

• Deteriorating water quality, due to ‘blooms’ of phytoplankton (microscopic algae floating in the water); and • Widespread loss of seagrass as a result of light starvation, due in turn to the shading caused by increased growth of epiphytes (algae that grow on seagrass leaves) and phytoplankton.

1 Norm Halse, RecFishWest 2 The present Causeway design is the result of a joint agreement between the Australian Navy (that wanted an open trestle structure) and the FPA (that wanted a solid connecting groyne to provide maximum protection against westerly waves for a future merchant shipping harbour).

2 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Figure 1.1 Cockburn Sound

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 3 Due to public pressure, the Western Australian Government funded a three year (1976−1979) Cockburn Sound Environmental Study (DCE, 1979). The study identified a large variety of contaminants in industrial discharges to the Sound, and in groundwater underlying industries. The decline in seagrass meadows and increase in phytoplankton levels were, however, linked to a massive increase in nutrient loading to the Sound. It was estimated that over 90% of this increased nutrient loading came from two sources: the outfall shared by the Kwinana Nitrogen Company (KNC) and the CSBP fertiliser works, and the outfall of Woodman Point Wastewater Treatment Plant (WWTP). These two outfalls discharged the nutrients phosphorus and nitrogen, but nitrogen was identified as the main nutrient responsible for the increased algal growth. The KNC subsequently installed a steam scrubber to remove a large proportion of nitrogen from its effluent (December 1982), and the Water Authority of Western Australia diverted discharge from the Woodman Point wastewater treatment plant out of Cockburn Sound and into waters 4 km off Cape Peron (July 1984).

To assess the influence of changes in nitrogen loading to the Sound, weekly measurements of water quality over summer (variously funded by government and industry) were carried out. These studies found that although water quality in the early 1980s was much improved compared to the late 1970s, it declined again during the late 1980s. This decline in water quality was one of the main triggers for the DEP’s 1991–94 Southern Metropolitan Coastal Waters Study (DEP, 1996). The EPA recognised that a better information base was needed to manage the cumulative impacts of waste discharges into local coastal waters. The SMCWS was undertaken to meet that need, and studied coastal waters from Fremantle to Mandurah, with particular attention to Cockburn Sound.

Key findings of the SMCWS for Cockburn Sound were as follows:

• Nutrient-related water quality in the early 1990s was only slightly better than in the late 1970s; • Seagrass dieback had slowed considerably, but some losses were still occurring (mainly at the southern end of the Sound) and there was no evidence of seagrass re-establishment anywhere; • Unlike the 1970s, industrial outfalls were no longer the main source of nitrogen entering the Sound. Instead, an estimated 70% of nitrogen inputs was from contaminated groundwater under two industrial sites: the coastline next to Western Mining Corporation and CSBP, and north of the shipbuilding area in Jervoise Bay; • Contaminant inputs from industry were far less than in the late 1970s. Levels of metals and organic contaminants (e.g. pesticides and petroleum products) in sediments and mussels were generally well below environmental guidelines and food standards, except for arsenic and mercury levels in sediments at a few sites. • There was widespread contamination of sediments and mussels with tributyltin (TBT, a highly toxic ingredient in antifoulant paints commonly applied to boats), with particularly high levels near harbours, marinas and commercial and naval wharves; • All beaches monitored met human health guidelines for swimming and shellfish harvesting, except Palm Beach, which exceeded the shellfish harvesting guideline for faecal bacteria; and

4 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE • At least 18 species of foreign marine organisms were present, brought in by discharge of ship ballast water and/or shedding of organisms attached to ships’ hulls.

Economic development of the Cockburn Sound region also accelerated in the 1990s, with a series of large-scale developments along the eastern margin of Cockburn Sound being proposed, including:

• A residential marina in Mangles Bay (Department of Transport); • Long-term plans for a harbour at Naval Base/Kwinana (Fremantle Port Authority); • An additional berth at the FPA bulk cargo jetty (Fremantle Port Authority); • A private port at James Point (James Point Pty Ltd); and • Industrial infrastructure and harbour development in southern Jervoise Bay Southern Harbour (Department of Commerce and Trade).

Due to concerns about the cumulative environmental impact of these developments, the EPA prepared Bulletin 907; strategic environmental advice for the marine environment of Cockburn Sound (EPA, 1998). A key recommendation of Bulletin 907—based in turn on a recommendation of the SMCWS (DEP, 1996)—ultimately led to the formation of the CSMC.

1.3 ENVIRONMENTAL MANAGEMENT APPROACH FOR COCKBURN SOUND One of the main objectives of the SMCWS was to design a coordinated management approach for the protection of Perth’s coastal waters from pollution, which could then be extended in principle to other coastal areas of Western Australia (DEP, 1996). This approach involved the following steps:

• Identification of Environmental Values (EVs) for coastal waters; • Identification of Environmental Quality Objectives (EQOs) to support the EVs; • Deciding the areas where various EQOs will apply; and • Development of Environmental Quality Criteria (EQC) to ensure the EQOs will be met.

A discussion paper addressing the above issues was released on 19th October 1998 (EPA, 1998), followed by public workshops and an invitation for written public comment between 19th October and 18th December 1998 (Jacoby et al., 1999). At these workshops it was recognised that Perth’s metropolitan coast is no longer as it was before European settlement, and population pressure alone prevents a return to ‘natural’ conditions even with the most stringent management measures. What can be achieved is ecologically sustainable development, in which environmental, social and economic goals are integrated.

In February 2000 the EPA released a working document describing Environmental Values (EVs) and Environmental Quality Objectives (EQOs) for Perth’s coastal waters (EPA, 2000). The EVs recognise the importance of the marine environment in terms of:

• Ecosystem health; • Fishing and aquaculture;

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 5 • Recreation and aesthetics; and • Industrial water supply.

Six EQOs, or specific management goals, were developed to protect these EVs. The EQOs, and their relationship to the EVs are shown in Table 1.1.

Table 1.1 Relationship between Environmental Values and Environmental Quality Objectives

ENVIRONMENTAL VALUE ENVIRONMENTAL QUALITY OBJECTIVE Ecosystem health EQO 1. Maintenance of ecosystem integrity Fishing and aquaculture EQO 2. Maintenance of aquatic life for human consumption Recreation and aesthetics EQO 3. Maintenance of primary contact recreation values EQO 4. Maintenance of secondary contact recreation values EQO 5. Maintenance of aesthetic values Industrial water supply EQO 6. Maintenance of industrial water supply values

The above management approach taken by the EPA/DEP is broadly consistent with that recommended by the National Water Quality Management Strategy (NWQMS), as outlined in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ARMCANZ, 2001, due for imminent release). Western Australia is a signatory to the NWQMS.

The national approach to setting environmental guidelines (similar to EQC) has moved away from single values that divide what is environmentally acceptable from what is not (ANZECC/ARMCANZ, 2001). Instead, conservative guidelines are proposed that are well below any real cause for environmental concern, but which are sufficient to ‘trigger’ further investigations to determine whether a problem might exist. This approach also allows local environmental conditions and the environmental sensitivity of local species to be taken into account.

The EPA/DEP held a series of workshops in February 2001 to start deriving EQC. The types of measurements for which EQC are being developed include:

• Nutrient-related effects; • Contaminant levels in water and sediments; • Biological indicators of excessive levels of contaminants or nutrients (e.g. imposex3 in marine snails; • Safety of seafood for human consumption; • Recreational safety (e.g. faecal bacteria in water, harmful algal blooms); and • Aesthetics (e.g. water clarity and colour, dust films, faunal deaths, rubbish, maintenance of aesthetic features and natural character of the area).

The Cockburn Sound EPP builds on the national strategy by setting three levels of EQC that demarcate increasing levels of management intervention linked, in turn, to increasing levels of environmental risk. The first level of EQC—which, if met, means no management intervention is needed—will be based largely on the national guidelines (ANZECC/ARMCANZ, 2001), in accordance with their intended purpose. The types of EQC and their derivation are explained in full by McAlpine and Masini (2001).

3 Development of male reproductive organs in females due to the antifoulant ingredient TBT

6 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 1.4 THIS DOCUMENT This report on the State of Cockburn Sound, follows the Pressure-State-Response (P-S-R), model of the Organisation for Economic Co-operation and Development (OECD), that has been adopted by National and State governments in Australia for State of the Environment (SoE) reporting (Figure 1.2).

Figure 1.2 The Pressure-State-Response model

The report is intended to:

• Summarise and update the findings of the SMCWS for Cockburn Sound; • Focus on the main factors affecting environmental management; and • Be written in style suitable for the interested public.

The report is not intended to be as detailed or as comprehensive as the SMCWS. Also, as a broad cross-section of people were consulted during preparation of the report, opinions sometimes differed on how environmental data should be interpreted and/or what the most the important factors influencing the environment were. In addition, comments or explanations were sometimes offered in the absence of sufficient data to back them, usually to stimulate further discussion and/or direct further work. Where the report cites differing opinions or speculative statements, these are clearly identified as such.

The structure of the report follows that of the EMP being prepared by the CSMC, and so addresses four main ‘components’: marine, land, social/cultural and economic. These four components are addressed in Sections 2, 3, 4 and 5, respectively.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 7 The marine component (Section 2) follows P-S-R format, describing the environmental state of Cockburn Sound, the main pressures on it, and the responses currently in place to manage those pressures. Key gaps in management responses and information are also identified.

The land, social/cultural and economic components (Sections 3, 4 and 5) provide more detail on these human uses of Cockburn Sound and its catchment that are causing pressure on Cockburn Sound. The management responses to those pressures are also described, and the key gaps in management and information identified. Land uses, social/cultural uses and economic uses are considered only as far as their potential for pressure on Cockburn Sound.

The final section (Section 6) recommends a research and investigation programme to provide key information that will improve environmental decision-making.

8 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 2. MARINE COMPONENT

2.1 REGIONAL CONTEXT The present Perth metropolitan coastal region was formed by a sea level rise that took place about 10,000 years ago. At that time, the sea-level was approximately 27 m below present, but rose rapidly over a period of about 3,600 years to reach 3 m above its present level. Sea level then dropped slightly to reach the present level, about 1,500 years ago, and has stayed relatively constant since then.

The sharp rise in sea level between 10,000 and 6,400 years ago drowned the previous shoreline. The present shoreline was formed when the sea spilled over the Garden Island Ridge into lower land known as the Warnbro-Cockburn Depression. This depression is bounded on its eastern side by the Spearwood Ridge that forms the basis of the mainland shore today. Only the high points of the Garden Island Ridge remain, and form the offshore chain of islands (Penguin Island, Garden Island, Carnac Island) and reefs seen today (Figure 1.1). Further west another ridge, the Five Fathom Bank Ridge, is completely submerged (Figure 1.1). These two lines of islands and reefs protect Perth’s southern coastal waters from ocean swell to varying degrees.

The Five Fathom Bank Ridge, Garden Island Ridge and Spearwood Ridge are made up of limestone (Tamala Limestone). Wave action has eroded much of the two submerged ridges, and transported the eroded sands shorewards. Today’s shoreline therefore consists of sandy beaches and limestone rocky shores and headlands, while the seabed consists of extensive sandy areas and limestone reefs. In some areas, the pattern of wave action has deposited sand at right angles to the shore, forming shallow sandy banks that separate deeper areas. Cockburn Sound is separated from Warnbro Sound by Rockingham Bank, and from Owen Anchorage by Parmelia Bank (Figure 1.1).

The coastal waters of the region are strongly influenced by the Leeuwin current, which flows from the equator southwards along WA’s coast. The waters of the Leeuwin current are clear, warm and low in nutrients. Nutrient input to coastal waters from rivers is also low (by world standards). In addition, due to the pronounced Mediterranean climate of the region (long, hot, dry summers and cool wet winters), most river flow occurs in winter and early spring, with little or no river flow to the sea from late spring to early autumn. Nor are there any nutrient-rich upwellings of colder, deeper water, such as occur off the south coast of Africa and South America.

Due to the above combination of factors, the nearshore coastal waters of the south- west of WA are—by world standards—shallow, nutrient-poor, clear, and of low to moderate wave energy. The strength of the Leeuwin Current and amount of outflow from rivers also varies considerably from year to year, which can affect regional water quality.

2.2 ECOSYSTEM OVERVIEW The nutrient-poor waters of the south-west of WA support little growth of plankton (microscopic plants and animals), and so lack the rich plankton-based fisheries of south-west Africa and South America. Instead, marine plant production is dominated by seagrass ‘meadows’ on the shallow sandy areas (which contribute both seagrass and epiphyte production), and seaweed ‘gardens’ on the reefs. The fisheries depend

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 9 on the production of these reefs and seagrass meadows, and so are described as ‘benthic’ (seabed)-based, rather than plankton-based. The diversity and abundance of marine species is highest in and around the reefs, followed by seagrass meadows. The deep basins (e.g. Cockburn Sound) also support a rich seabed community dominated by species that feed on detritus (dead and decaying organic material). Perth’s coastal waters are essentially a temperate environment, but tropical species are also found due to the influence of the Leeuwin Current. Perth is within a region of ‘biogeographical overlap’ that extends from Cape Leeuwin to North West Cape, in between the main temperate biogeographic region (Cape Leeuwin to South Australia) and tropical biogeographic region (north-east of North West Cape). This overlap region has fewer species than the two main biogeographic regions. Perth’s waters are at the southern end of the overlap region, and so temperate species predominate. Endemic species (i.e. species only found in Western Australia) make up 10–25% of the species in Perth’s metropolitan waters, depending on the type of organism (e.g. crustaceans, shellfish, worms) in question. Although the region is relatively poor in marine species in general, it has the highest number of species of seagrass in Australia. There are only about 50 species of seagrass worldwide, 13 of which are found in Perth’s coastal waters. There are six main ‘meadow-forming’ species: Amphibolis griffithii, A. antarctica, Posidonia australis, P. sinuosa, P. angustifolia and P. coriacea.

The most dense stands of seagrass occur in shallow sheltered areas and consist of meadows of P. sinuosa or P. australis. Cockburn Sound had extensive areas of these species before the massive seagrass loss that occurred in the late 1960s/early 1970s. Less sheltered areas (e.g. Owen Anchorage, and much of Marmion Marine Park) tend to have patchy meadows of A. griffithii and P. coriacea; species that can tolerate greater wave and current action than P. sinuosa and P. australis.

As noted in Section 1.1, Cockburn Sound is unique along Perth’s metropolitan coast due to its degree of shelter from ocean shell, and its depth. These physical features are responsible in turn for its regional significance in ecological terms: extensive areas of species of seagrass that prefer sheltered conditions, and organic-rich silts on the seabed of the deep basin that support species of plants and animals not found elsewhere on the central west coast of Western Australia, other than Warnbro Sound.

2.3 STATE OF THE MARINE ENVIRONMENT

2.3.1 Water movement in the Sound Modelling of water movement in Cockburn Sound—and of substances transported by water—has been the subject of a number of studies from about 1977 until present. The hydrodynamics of the Cockburn Sound region have been reviewed in some detail by Hearn (1991), D’Adamo (1992) and the DEP (1996). There are also numerous detailed supporting documents of field work and modelling studies carried out as part of the SMCWS that are summarised and referenced in DEP (1996). Studies since 1996 have been more ‘site-specific’ than ‘ecosystem-wide’, and have focussed on the effects of proposed developments within and adjacent to Cockburn Sound: these studies have not altered the fundamental understanding of water movement in the Sound (as established in earlier work), but have refined understanding of some aspects. The following summary is drawn largely from work done up to 1996, while areas of improved understanding due to more recent work are also discussed.

10 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE The hydrodynamics of Perth’s coastal waters is a complex combination of wind- forced waves, tides, large-scale currents (the Leeuwin and Capes Currents) and localised currents due to density differences in the water column, and long period waves (Pattiaratchi et al., 1995). The complexity is due to variations in the relative strength of each of these factors with the weather and season.

Very little offshore wave energy reaches Cockburn Sound due to the shelter provided by Garden Island along the western shore, the Causeway at the southern end of the Sound, and Parmelia Bank at the northern end of the Sound (2–5 m deep, apart from the 150 m-wide FPA channel, which is 14.7 m deep). The sheltering effect of these physical barriers during a severe winter storm is shown in Figure 2.1.

Figure 2.1 Wave height in Cockburn Sound during a severe storm with westerly winds Note : From MRA (2000). Reproduced with permission from Cockburn Cement Limited. Colour grading from large waves in red through to small waves in blue.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 11 As little as 5% of the swell wave energy penetrates to southern Cockburn Sound (DEP, 1996). However, the degree of shelter depends on wave direction and the location within Cockburn Sound being considered. For example, the gap between Carnac Island and Garden Island allows some west and north-west swell to reach James Point, while Southern Flats and the Causeway prevent most south-west swell from reaching James Point.

As a result of the protected nature of the Sound, the three main processes that control its hydrodynamics are (Hearn, 1991):

• Wind; • Horizontal pressure gradients due to wind, tides, waves, atmospheric pressure and continental shelf waves (which create differences in water pressure due to differences in water level); and • Horizontal pressure gradients due to buoyancy effects (differences in water density).

The three main processes are briefly described below.

Wind Waves and currents in Cockburn Sound are primarily a result of wind forcing. During summer the dominant wind direction is south to south-west, and winds are typically quite persistent: 50% of winds have speeds of 5–9 m/s. The daily sea breeze cycle is also very important. In winter the main wind direction is westerly, though northerly winds often occur: winds are more variable with occasional periods of calm and strong storm winds, and 50% of winds have speeds of 2–7 m/s.

The wave climate in Cockburn Sound is dominated by wind-generated waves. Data from 1996-1997 indicate that typical waves in summer have a significant wave height (i.e. the height of the highest one third of waves) of <0.7 m. During winter storm events, significant wave height approaches 1.25 m (JPPL, 2001).

Wind is also the main driving mechanism of circulation within the Sound when the wind speed is above 5 m/s. During calm periods (wind speed <5 m/s), circulation within Cockburn Sound becomes complex and is driven by a combination of wind and horizontal pressure gradients.

Along the coastal margins of Cockburn Sound and in the surface waters (to a depth of at least 10 m) the net current is northward during summer, due to the prevailing south to south-westerly winds. Current velocities are up to 0.2 m/s during average conditions and are strongest offshore from James Point. During winter, and periods of calm, the current velocities drop to below 0.1 m/s. The shallow inshore region has strong, depth-averaged wind-driven flows, but bottom friction results in relatively rapid (12–24 hours) reduction in flows after the onset of calm conditions (Hearn, 1991). This feature is important when assessing circulation responses with the onset of calm conditions. Surface currents under typical summer conditions, and under northerly winds in winter, are shown in Figure 2.2.

Depth-averaged currents provide an indication of the net transport within Cockburn Sound in summer. The circulation pattern is dominated by two gyres: one circulating anti-clockwise in the region north of James Point, and one clockwise in the region south of James Point. These two gyres are shown in Figure 2.3. The gyres are due to wind-driven flow in the shallow nearshore regions and return flow against the wind at depth (approximately below 10 m). The return flow at depth

12 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE against the wind arises from alongshore pressure gradients generated by the wind driven flow.

Figure 2.2 Surface circulation patterns during summer (left) and winter (right) Note: Adapted from PHC (2000) Oceanographic Review - Project C4: Effects on Circulation and Exchange from the Construction of a Seaway through Success and Parmelia Banks, reproduced with permission from Cockburn Cement Limited.

Figure 2.3 Depth-averaged currents during summer in Cockburn Sound and surrounds Note: Obtained from modelling work done as part of PHC (2000) Oceanographic Review - Project C4: Effects on Circulation and Exchange from the Construction of a Seaway through Success and Parmelia Banks. Reproduced with permission from Cockburn Cement Limited.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 13 Horizontal Pressure Gradients Horizontal pressure gradients are the result of differences in water pressure between two areas. Differences in water pressure may be grouped into those driven by wind, tides, waves, seiches and atmospheric pressure (i.e. differences in water pressure due to differences in water level); and those driven by horizontal differences in water density (often called ‘buoyancy effects’). Each is discussed below.

a) Gradients due to wind, tides, seiches, waves and atmospheric pressure Changes in water levels due to different forcings occur at different time scales, and may be periodic (e.g. tides) or irregular (e.g. continental shelf waves). Changes due to winds can happen over daily time scales, while tides and seiching produce effects over weekly time scales. Sea level is also influenced by the passage of high pressure systems, storm surges and other long period forcings, including continental shelf waves (DEP, 1996), and these occur over time scales greater than a week.

Changes in water level due to wind are the result of the interaction of wind and the complex topography of the coastline. During periods of strong wind such as a north- west or westerly storm, water is pushed up against the coast by wind and wave forcing. The more enclosed a basin, such as Cockburn Sound, the greater the ‘setup’ of water against the coast. More open coastal regions surrounding Cockburn Sound may not have as much setup, and the difference in water level between Cockburn Sound and adjacent areas drives the circulation.

Changes in water level due to tides and seiching result in current speeds that are generally between 1–2 cm/s. The tidal range is between 0.1 and 0.9 m in Cockburn Sound but is typically around 0.5 m. The tidal cycle is usually daily (one high and one low water per day), but sometimes twice-daily. Changes in water level during daily tides are 2–3 times higher than during twice-daily tides. Seiching is the result of the water level in the Sound oscillating in response to a disturbance such as a change in wind forcing. Although seiching contributes variations to the sea level of 0.1 m in Cockburn Sound, effects on current speeds are generally small to negligible.

Changes in water level due to high pressure systems, including storm surges and continental shelf waves depend on both local and remote weather conditions. Low frequency oscillations, such as continental shelf waves, are able to penetrate Cockburn Sound (Hearn, 1991) and can contribute approximately 10 cm/s to ambient current speeds.

b) Buoyancy effects The saltier and/or colder that water is, the more dense it is. Buoyancy effects arise when waters of differing densities are adjacent to one another, with the less dense water flowing over the denser water. A well-known example of buoyancy effects is the flow of seawater up the Swan River close to the river bed, while surface fresh water flows the opposite direction toward the sea.

In Cockburn Sound, horizontal density differences can be caused by groundwater discharge; differences in evaporation and cooling between Cockburn Sound and adjacent waters; flow from the Swan River; cooling water discharges; and differences in cooling between nearshore waters and deeper basin waters. These density differences can influence circulation in localised areas such as the nearshore region (due to differential heating and cooling, groundwater discharge, cooling water discharge), or over the entire Sound (due to differential evaporation and cooling between Cockburn Sound and adjacent waters, Swan River discharge).

14 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE In autumn the waters of Cockburn Sound are typically more dense than adjoining areas, and horizontal density gradients lead to the movement of buoyant (i.e. less dense) water into the Sound. These less dense, surface waters result in distinct vertical layers of water (termed ‘stratification’) within Cockburn Sound. Under stratified conditions, diffusion of oxygen from surface waters to deeper waters is slowed, and the rate of oxygen demand by organisms in the deeper waters and on the seabed may exceed the rate of supply. Wind of sufficient strength and duration (see below) can break down this stratification and mix the waters column vertically, but during extended periods of calm (e.g. greater than a week), deeper waters within Cockburn Sound can become oxygen depleted. Severe oxygen depletion can have profound ecological effects, including the death of organisms, and increased sediment nutrient release which, in turn, can worsen water quality.

In winter and spring the waters of the Sound are typically less dense than adjoining areas, and denser water moves into the lower depths of Cockburn Sound during calm periods. This dense water is mixed into the lighter surface layer during periods of storm activity (D'Adamo and Mills, 1995). In the absence of storms, the denser waters at the bottom of the Sound also result in stratification, increasing the likelihood of oxygen depletion.

The horizontal pressure gradients due to density differences between Cockburn Sound and adjacent waters determine the flushing of Cockburn Sound during the autumn and winter-spring seasons. Density gradients act to transport water into and out of Cockburn Sound during calms, thereby flushing the surface waters in autumn and the bottom waters in winter. Flushing of the bottom waters of Cockburn Sound during autumn, and of surface waters during winter, depends on wind events that mix the whole water column (generally requiring wind speeds >5 m/s for 2-3 days or more), followed by re-establishment of density gradients. Such wind events are rare in autumn, and so the deep basin waters of the Sound are particularly poorly flushed in autumn.

Seasonal patterns in water movement Three distinct hydrodynamic regimes have been identified in Cockburn Sound based on the relative importance of wind and pressure gradients in determining circulation patterns and flushing: ‘summer’, ‘autumn’ and ‘winter-spring’ (DEP, 1996). The key characteristics of the three seasons are as follows:

• Summer. During summer, winds are the most important factor controlling the hydrodynamics. Circulation is wind-driven (see Figure 2.2 and Figure 2.3) and the waters within both the Sound and adjacent waters are vertically well mixed (Figure 2.4)—and therefore well oxygenated—due to a combination of wind mixing during the day (due to sea breezes) and surface cooling of the water column at night (cooler surface waters sink towards the seabed, enhancing vertical mixing); and • Autumn. During autumn the wind subsides and pressure gradients determine the circulation. The waters in the Sound are of a greater density (cooler and more salty) compared to adjacent waters due to evaporation that has occurred during the summer and rapid cooling during autumn (Figure 2.5). The gradient between the denser waters of Cockburn Sound and the lighter adjacent water controls the flushing of Cockburn Sound to the greatest extent. Stratification within the Sound becomes apparent due to movement of lighter water into the Sound, and as noted previously, extended periods of calm may result in oxygen depletion of bottom waters.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 15 Figure 2.4 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative of summer Note: From D'Adamo and Mills (1995). Density contours are density value minus 1000 kg/m3. Transect location on the right.

Figure 2.5 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative of autumn Note: From D'Adamo and Mills (1995). Density contours are density value minus 1000 kg/m3. Transect location on the right.

16 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE • Winter-spring. In this ‘season’ the circulation is primarily driven by pressure gradients, punctuated by periods of wind-driven circulation due to storm activity (see Figure 2.2). The waters within the Cockburn Sound become progressively lighter than waters further offshore (Figure 2.6) due to the relative lowering of salinity. Salinity is lowered within Cockburn Sound due to freshwater inflow, particularly from rivers. The relatively rapid response of the shallow waters of Cockburn Sound to heating (compared to offshore waters) as spring progresses also contributes to the relative decrease in density. Denser water moves into the lower depths of Cockburn Sound during calm periods (wind speeds typically less than 5 m/s), and stratification persists until broken down by the passage of winter low pressure systems about every 7-10 days (D'Adamo and Mills, 1995).

Figure 2.6 Transect from Fremantle through Cockburn Sound and out through the Causeway, showing water density conditions representative winter-spring Note: From D'Adamo and Mills (1995). Density contours are density value minus 1000 kg/m3. Transect location on the right.

Recent modelling of water movement in Cockburn Sound Since the SMCWS (DEP, 1996) modelling of Cockburn Sound has been confined mainly to developments along the eastern margin of Cockburn Sound. Recently, models have been developed to examine the impact of: the ‘Seaway’ (widening of the present FPA channel from 150 m to 1.5 km) proposed as part of Cockburn Cement’s Environmental Review and Management Programme (Cockburn, 2000); the James Point Pty Ltd Stage One Development, (JPPL, 2001); and cooling water discharges north of James Point. These models can examine effects at smaller scales (50–100 m) and incorporate a greater range of physical processes than models previously applied to Cockburn Sound. The models are able to simulate physical processes at a 50–100 m scale along the eastern margin of Cockburn Sound and a 250–300 m scale in the remainder of the Sound, over weekly time-scales.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 17 The recent studies of Cockburn Sound have furthered understanding in two areas: the flushing of Cockburn Sound; and the hydrodynamics of the eastern margin, including the characteristics of the cooling water discharges north of James Point.

Flushing is a measure of the exchange and replenishment of the water in an area with surrounding water. A long flushing time reflects low exchange with adjacent waters and a short flushing time reflects higher exchange. The water quality of Cockburn Sound is due in part to its enclosed nature, which reduces exchange with the water of Owen Anchorage to the north and the open ocean to the west. Flushing times affect the dilution of nutrient and contaminant inputs as well as a variety of ecological processes, and can be used to assess the ecological implications of changes in the circulation of Cockburn Sound.

There are many ways to measure the time over which Cockburn Sound is flushed. To be consistent with previous modelling of Cockburn Sound (DEP, 1996) the ‘e-folding’ time has been used, which estimates the time taken for 63% of Cockburn Sound to be flushed. A summary of the most recent estimates of flushing times is given in Table 2.1, and are consistent with previous estimates by the DEP (1996).

Table 2.1 Flushing times for Cockburn Sound

AUTUMN WINTER WINTER STORM SUMMER 37 days 22 days 28 days 44 days Note: Reproduced with permission from Cockburn Cement Limited (Cockburn,, 2000).

The above estimates refer to flushing of the Sound as a whole. Flushing is least in summer because the prevailing winds set up circulation gyres that tend to confine water within the Sound (Figure 2.3). As noted previously, flushing in winter is primarily due to the horizontal pressure gradients (buoyancy) that occur: flushing during winter storms is actually less because wind mixing lessens the pressure gradients that drive water movement. Flushing in autumn is also primarily due to pressure gradients, but takes longer than flushing in winter: this is mainly because the movement of denser bottom waters out of the Sound (over the barrier of Parmelia Bank and through the Causeway) in autumn requires more energy than the movement of denser waters into the Sound during winter. There is also little vertical mixing (due to wind) in autumn to aid flushing of bottom waters.

Flushing times in more ‘localised’ areas along the eastern margin of the Sound have been also estimated to examine the impact of proposed harbour developments, and include the influence of cooling water discharges from Western Power and the BP Refinery (JPPL, 2001). The shallow waters of the eastern shelf are well mixed and flushing times are approximately 1 day or less. Flushing times are far greater in the partially enclosed waters of the Jervoise Bay Northern Harbour, generally 5–14 days. The most poorly flushed area of the Sound is considered to be the bottom waters of the southern basin, but no estimates of flushing times have been made.

There have been no investigations of changes in flushing times from year to year due to changes in wind patterns and pressure gradients (e.g. due to differences in Swan River flow, groundwater discharge).

2.3.2 Coastal processes Coastal areas are seldom stable. There is nearly always some degree of erosion or accretion (accumulation) occurring at the shoreline, although this may balance out over a year or more. This erosion/accretion of the shoreline occurs because sand is suspended into the water by waves breaking on the shore: if the waves are

18 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE approaching the beach at an angle, this creates a longshore current that can move the suspended sand. This transport of suspended sand is accompanied by ‘bedload’ transport, where sand is rolled over the seabed by the force of the breaking waves. Waves, nearshore currents, the weather (winds, barometric pressure) and changes in water level are important factors determining erosion/accretion patterns at the shoreline. Artificial structures such as groynes, harbours and offshore breakwaters alter natural patterns of longshore sediment movement.

Two forces have generated the present coastal morphology of Cockburn Sound: southerly wind systems that set-up longshore sediment transport through local wind waves and longshore currents during the spring and summer months; and north-west storm systems consisting of swell waves, local wind waves and wind-driven currents. The relative contributions of these forces are in a close balance, with a small net southerly trend leading to the accretion that has formed James Point.

The sheltered nature of Cockburn Sound results in less wave energy to move sediment compared to other metropolitan beaches, and changes in the Sound’s coastline evolve relatively slowly. Changes to the coastline due to development are occurring more quickly than adjustment of sand movement patterns to those developments.

Environmental Resources of Australia (ERA, 1973) examined aerial photographs taken between 1954 and 1972, and found that the beaches within Cockburn Sound were accreting. The most notable area of accretion was where the Garden Island Causeway joined the mainland, and this accretion was occurring before the Causeway was constructed. A significant exception to the pattern of accretion was at James Point, where the shoreline retreated approximately 30 m, and this was verified by measurement of beach profiles (ERA 1972, 1973).

The loss of extensive seagrass meadows from the eastern margin of Cockburn Sound between 1967 and 1973 was believed to have accelerated erosion at James Point during 1971 (ERA, 1972). However, the Causeway was also constructed around the same time (1971–1973), which reduced the wave energy arriving at James Point from the south-west by up to 75% (Hsu, 1992), resulting in proportionally more energy arriving from the north-west, and reinforcing southerly movement of sediment. Due to the loss of seagrass and the construction of the Causeway at about the same time, plus the relatively slow response of the shoreline to those changes, it is not possible to say which of these two events was responsible for alterations to the coastline after the late 1960's/early 1970's. Recent modelling of wave conditions in Cockburn Sound (during a moderate swell, a typical sea breeze pattern, a moderate storm and a severe storm) has also predicted a net annual direction of sediment movement from north to the south within Cockburn Sound, except at the Rockingham Jetty (MRA, 2000). Modelling results suggest this net movement is at least partly due to the Causeway reducing the amount of swell energy entering the Sound from the south.

Coastal processes and shoreline stability have been investigated at some specific areas around Cockburn Sound, generally due to proposed developments (James Point, Mangles Bay) or as a result of existing developments (Jervoise Bay, Woodman Point and Mangles Bay). The coastline in the vicinity of James Point has been investigated to the greatest technical extent due to the protection of this headland by the establishment of offshore breakwaters (Hsu, 1992) and proposed developments to the north (JPPL, 2001). The following sections summarise what is known about these areas.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 19 James Point Examination of the vegetation line between Naval Base and James Point since the construction of the Causeway has shown the shoreline to be stable with episodes of local change (Andrews, 1979). Localised changes have been pronounced at James Point due to the higher wave energy and currents relative to the majority of the Cockburn Sound coastline (see Figure 2.1 and Figure 2.2).

Severe erosion of the small sand cliffs at James Point has occurred since 1953 and has been attributed to the passage of north-west storms (Hsu, 1992). The low pressure associated with these storms raises the water level, allowing wave attack to occur higher up the beach line, resulting in the erosion of the sand cliffs behind the primary dunes. When sand is eroded from these cliffs it is moved onto the beach and then subsequently offshore or along-shore. After a storm, sand cannot be returned to the cliff face and the erosion is permanent. To prevent further erosion of the beach at James Point, offshore breakwaters were constructed to increase the beach width and therefore reduce the effect of the storm surge.

Aerial photographs indicate that the shoreline immediately north and south of James Point has remained relatively stable. The BHP jetties to the north of James Point have had minimal impact on the shoreline position. Aerial photographs from 1973 to 1999 also show that there is relatively large seasonal sedimentation around the Western Power intake and outfall infrastructure. When northward transport is dominant (summer months) the sedimentation is to the north of this area, and during the winter months it is to the south.

Overall, aerial photographs indicate that net sediment transport is to the south: the sand moves along the beach north of James Point and becomes trapped at James Point.

Mangles Bay Erosion has been occurring in Mangles Bay since the Causeway was constructed. The Causeway prevents the natural pattern of sediment movement from Cape Peron into Cockburn Sound (DMH, 1992), and so there is accumulation of sand on the western side of the Causeway and erosion on the eastern side to as far as the Bell Street Boat ramp (Figure 2.7). This erosion is still continuing, and is mitigated by transport (by truck) of sediment from the western side of the Causeway to the eastern side (pers. com. Gary Middle, Shire of Rockingham).

Woodman Point and Jervoise Bay Woodman Point and Jervoise Bay have undergone changes due to developments since 1913. Of greatest significance in this region are the Woodman Point and WAPET Groynes, built off the tip of Woodman Point. Between 1913 and 1918 Woodman Point was built out approximately 400 m and extended south-westward a similar distance by means of a rubble structure, as part of a plan to develop the peninsula into a naval facility (Powell and Emberson, 1981).

Jervoise Bay has also undergone development, particularly in the past 30 years. Modifications to the coastline in this region include dredging, infilling, and the establishment of breakwaters (1991 to 1997) to encompass the Northern Harbour. Due to the protected nature of this part of Cockburn Sound, changes to the coastline in response to these modifications have been gradual. The most recent studies in this area have been undertaken by MRA (2000) for the Department of Commerce and Trade, and Andrews (1979).

20 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Figure 2.7 Shoreline movement in Mangles Bay from DMH (1992) The present erosion of the beach to the west of the Northern Harbour is of considerable concern to local beach users. Due to the many alterations that have already occurred in this area plus the slow response times of the coastline, it is proving difficult to decide the main factor(s) responsible for the erosion and develop a mitigation plan.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 21 2.3.3 Water quality The water quality of Cockburn Sound during ‘summer’ (December to March) has been monitored at the same eight sites (Sites 4–11 in Figure 2.8) every one to three years since 1977.

10m

Carnac Island WP Woodman Point

NC 6a 6b 5 4

7 10m

10m

G

a

r d

e n 8

I s

l a n 9 d

Careening Bay

10m 10 Kwinana SC Beach 11

Mangles Bay 01 Cape Peron km N

Figure 2.8 Summer water quality monitoring sites in Cockburn Sound Note: The original site 6 was lost when the northern breakwater of the Jervoise Bay Northern Harbour was built.

Average water temperature in the Sound varies from about 16°C in winter to 24°C in summer (the shallows are 2–3°C cooler in winter and 2–3°C warmer in summer). Water salinity varies slightly from that of the open ocean (which is about 35 parts per

22 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE thousand), typically declining to about 34 ppt in winter (due to outflow from the Swan River) and reaching 36 ppt in autumn (due to evaporation during the summer months).

The waters of the Sound are generally well oxygenated, although if calm weather persists for more than a week the deep waters at the southern end of the Sound may become low in oxygen. This is because bacteria in the organic-rich sediments use up oxygen faster than the water can supply it. Oxygen levels in the bottom waters sometimes become so low that the bacterial decay of sediment organic matter is affected, and the release of nutrients from sediments to the water column increases.

Water quality monitoring in Cockburn Sound focuses on nutrient-related effects, especially the growth of phytoplankton (measured as ‘chlorophyll a’ levels) as this provides a good indication of the available nutrient supply. Water clarity (measured as ‘light attenuation’) is also a useful measure, as it is affected by phytoplankton levels. Monitoring of contaminants (e.g. metals, pesticides) in water is not done routinely, as levels are generally too low to detect. Sediments and marine organism accumulate contaminants, and so are a better means of detecting long-term, low-level contaminant inputs (see Section 2.3.4).

Summer water quality data for Cockburn Sound (based on all eight sites) from 1977 onwards are shown in Figure 2.9, along with the summer nutrient inputs from human activities as estimated using the methods of Muriale and Cary (1995). Estimated nutrient inputs from 1990 onwards differ slightly from those of Muriale and Cary (1995), as better estimates of the groundwater inputs from the Kwinana Nickel Refinery area are now available.

Summer N inputs versus chlorophyll 900 4 Summer N input Summer c hl. 3 600

2

300 1 N input (tonnes) Chl. levels (ug/L) Chl.

0 0 1977 1981 1985 1989 1993 1997 2001 Year

Figure 2.9 Summer chlorophyll levels in Cockburn Sound versus summer nitrogen inputs from human activities (outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) Note: The green symbol for chlorophyll gives the mid-point of the data range, and the vertical bars show the middle 50% of the data. This gives an indication of how much the values fluctuate over summer. The blue vertical bars show ±30% of nutrient inputs, which is the typical error associated with estimating both outfall discharges (Martinick and Mackie Martin, 1993) and groundwater discharge (Appleyard, 1994).

The same information is repeated in Figure 2.10, but with nutrient input from the Woodman Point wastewater treatment plant (WWTP) excluded from summer nutrient inputs: this was done because there is some uncertainty about the degree of influence of nutrient inputs from the WWTP on overall water quality in the Sound up to 1984. The results of Chiffings (1979) indicate that the sewage plume did enhance phytoplankton growth in summer at least part of the time. More recent reviews

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 23 (Muriale and Cary, 1995) suggest that nutrient inputs from the WWTP were not as significant as first thought in influencing overall water quality, on the basis that typical surface currents during summer would have moved the largely buoyant sewage plume northwards out of the Sound most of the time (Mills and D’Adamo, 1995). This is supported by Figure 2.10, which shows a stronger relationship between nutrient inputs and chlorophyll level up to 1984 than evident in Figure 2.9.

Summer N inputs (minus WWTP discharge) versus chlorophyll 900 4 Summer N input Summer c hl. 3 600

2

300 1 N input (tonnes) N Chl. levels (ug/L) Chl.

0 0 1977 1981 1985 1989 1993 1997 2001 Year

Figure 2.10 Summer chlorophyll levels in Cockburn Sound versus summer nitrogen inputs from human activities (outfall discharges excluding the Woodman Point WWTP outfall; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) Note: Symbols as for Figure 2.9.

Regardless of whether Figure 2.9 or Figure 2.10 is referred to, it is clear that there has been a large decline in nutrient inputs to the Sound, but no similar scale of decline in chlorophyll levels. It is known that discharge from the KNC/CSBP pipeline had a major influence on overall water quality in the Sound up to at least 1990 (via large increases chlorophyll levels over the south-eastern part of the Sound), but chlorophyll levels from 1977 to the present cannot be predicted by means of a single, simple relationship to nitrogen inputs from human activities.

There have been a number of suggestions offered to explain the lack of a single, predictive relationship between estimated nitrogen inputs from human activities and overall chlorophyll levels in the Sound, as follows:

1. Up until 1991 the major source of nitrogen from human activities was discharge from the KNC/CSBP pipeline, and there was a clear relationship between estimated nitrogen inputs from human activities and overall chlorophyll levels in the Sound. Since then, nitrogen inputs from human activities have declined substantially and furthermore the major source is now groundwater diffusing in from about 1 km of shoreline south of James Point and in the vicinity in the Jervoise Bay Northern Harbour (see Section 2.4.3). The spatial pattern of increased chlorophyll levels produced by these two types of discharge appears to be quite different, and it is possible that groundwater nutrient inputs may result in more elevation of chlorophyll levels at sites along the eastern shore, whereas elevation of chlorophyll levels due to pipeline discharges was dispersed over a larger area. The relationship between nitrogen input and overall chlorophyll levels in the Sound (as detected by the eight sites monitored) has therefore changed.

24 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 2. Summer water quality was only measured once every 4–6 weeks up until the 1982/83 survey, when weekly measurements commenced. However, data for one site (site 10) were collected every week from in the summer of 1977/78 (Figure 2.11), unlike the other seven sites which were only monitored three times in the same period. If weekly data from December 1977 to March 1978 for this site are used, the median summer chlorophyll value is 4.3 µg/L, yet if only data are used from the three dates the other sites were sampled, the value is 2.7 µg/L. Thus, sampling up to the 1982/83 survey may not have been frequent enough to accurately document the chlorophyll levels present at the time, and the true extent of the improvement in water quality since the 1977–81 may not be reflected in Figure 2.9 or Figure 2.10. 3. Chlorophyll measurements in the early 1980s are underestimates due a change in measurement techniques at that time. The technique used in the early 1980s was found to produce artificially low results4. 4. Water quality data are based on eight sites. Improvements in water quality due a decrease in the area where high chlorophyll levels occur around any site(s) could be missed by the present sampling programme. 5. High chlorophyll levels in the summer of 1991/92 may be partly due to regional effects, notably the unusually long ENSO (El Nino/Southern Oscillation) event from 1990–1994 (atypically high chlorophyll levels also occurred in Warnbro Sound (see also Section 2.3.5). 6. The estimates of nutrient inputs are subject to large errors, particularly groundwater discharges. In addition, groundwater discharge is extremely variable both seasonally (maximum flow occurs in late spring/early summer), and with changes in sea level (e.g. due to tides, weather conditions).

Chlorophyll levels also vary widely between different parts of the Sound. In relative terms, the lowest levels occur in the central and western parts of the Sound (sites 4, 5 and 8), the highest values in the south-east (sites 9, 10 and 11) and within the Jervoise Bay Northern Harbour (site 6b), and intermediate values in the north-east (sites 6a and 7) (Table 2.2).

Table 2.2 Average chlorophyll levels at various sites in Cockburn Sound, summer 2000/2001

AVERAGE µg/L OF CHLOROPHYLL FOR SUMMER 2000/2001 (range shown in brackets) Site 4 Site 5 Site 6a Site 6b Site 7 Site 8 Site 9 Site 10 Site 11 0.8 1.0 1.4 8.6 1.4 1.2 2.1 2.5 1.9 (0.5–1.4) (0.7–1.7) (0.7–3.1) (1.1– (0.7–3.0) (0.5–1.9) (1.2–3.7) (1.3–3.7) (0.9–3.1) 43.3) Note: Data reproduced courtesy of the Kwinana Industries Council.

Differences in chlorophyll levels between individual sites occur due to differences in site-specific conditions such as flushing time, water circulation, water depth, and the size, proximity and type (eg. outfall discharge or groundwater) of nitrogen input(s). The influence of site-specific conditions is illustrated in data for sites 6, 8, 9 and 10 in Figure 2.11. The clearest and most dramatic example of the influence of site- specific conditions is evident at site 6, which receives significant nitrogen inputs from contaminated groundwater and has undergone significant changes in circulation and flushing rates through construction of the Jervoise Bay Northern Harbour.

4 Dr Rod Lukatelich, researcher at the Botany Department (University of WA) laboratory where the early 1980s work was undertaken. Currently Environmental Manager of BP Refinery.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 25 N inputs versus Site 6 chlorophyll

900 N inputs 8

Site 6a chl. ) ) Site 6b chl. 6 600

4

300 2 Chl. levels (ug/L N input (tonnes

0 0 1977 1981 1985 1989 1993 1997 2001 Year

N inputs versus Site 8 chlorophyll 900 8

N input 6 600 Site 8 chl.

4

300

2 Chl. levels (ug/L) N input (tonnes) N input

0 0 1977 1981 1985 1989 1993 1997 2001 Year

N inputs versus Site 9 chlorophyll 900 8 ) N inputs ) Site 9 chl. 6 600

4

300 2 N input (tonnes Chl. levels (ug/L

0 0 1977 1981 1985 1989 1993 1997 2001 Year

N inputs versus Site 10 chlorophyll 900 8

N inputs ) ) Site 10 chl. 6 600

4

300 2 N input (tonnes Chl. levels (ug/L

0 0 1977198119851989199319972001 Year

Figure 2.11 Summer water quality at Cockburn Sound sites 6, 8, 9 and 10, versus summer nitrogen inputs from human activities (outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading) Note: The original site 6 was built over by the Jervoise Bay northern breakwater in 1997. Site 6a is located 50 m west of site 6, and site 6b is located within the Jervoise Bay northern harbour.

26 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE At site 6 (Jervoise Bay) there was a steady decline in water quality in the 1990s. With the completion of the northern breakwater of the Northern Harbour in late 1997, water quality deteriorated inside the Harbour and generally improved outside the Harbour (based on comparisons with earlier data for site 6), although poor quality water from inside the harbour sometimes moves out of the harbour on outgoing tides and affects a larger area. These effects are evident in data from intensive summer monitoring (three sites in the Harbour and six sites outside), funded by the Department of Commerce and Trade (DAL, 2001), and are due to confinement within the Harbour of nitrogen-rich groundwater that had previously dispersed over a larger area of the Sound.

Site 9 is the site most affected by large inputs of nitrogen from industry in the past. The nitrogen inputs from industry in this area have decreased dramatically in the last 10 years, and there are signs of improvement in water quality. As noted earlier, the chlorophyll data for the late 1970s and 1980 may not accurately reflect the poor water quality at that time, and so the true extent of improvements at site 9 since the late 1970s may not be apparent in the data. Site 10 was also affected by the same industrial inputs as site 9 (although probably to a lesser extent given the summer pattern of water movement), and clearly shows the poor state of the Sound in the late 1970s. However, the water quality at site 10 has also shown some signs of worsening in the last few years (whereas site 9 appears to be improving), possibly indicating some other influence at this site.

Site 8 is in the middle of the Sound, and clearly has better water quality than Sites 6, 9 and 10 on the eastern margin of the Sound. Water quality at site 8 has changed little in the past 10 years, apart from the summer of 1991/1992, when there was a ‘Sound-wide’ increase in chlorophyll levels (also in Warnbro Sound; DEP, 1996). The reason for this regional increase remains unclear.

The data for sites 6, 8, 9 and 10 clearly show that total nitrogen inputs to the Sound due to human activities are less important in determining a site’s water quality than characteristics specific to that site. This is important to bear in mind when both predicting and managing water quality.

The above discussion focuses on the influence of nutrient inputs to Cockburn Sound due to human activities, but there is one additional final factor that plays an important role in determining water quality (and chlorophyll levels): sediment nutrient cycling. Simple diagrams showing estimated annual nitrogen inputs from human activities and annual rates of sediment nitrogen cycling in 1978 and 2000 are shown in Figure 2.12 and Figure 2.13, along with the amount of nitrogen needed by phytoplankton (microscopic algae in the water) and MPB (microscopic algae on and in the sediments). Sediment data for 2000 are based on Bastyan and Paling (1995, cited DEP, 1996). Sediment nutrient cycling in 1978 was estimated to be only slightly higher than in 2000. Although sediment nutrient levels in the southern basin of the Sound were markedly higher in 1978 (see Section 2.3.4) and so sediment nutrient cycling was assumed to be greater, this area only represents a small proportion of the Sound. There is little information on sediment nutrient cycling and historical changes in sediment nutrient levels for the shallow margins of the sand.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 27 Figure 2.12 Estimated nitrogen inputs from sediments and human activities in 1978, and amount of nitrogen required by phytoplankton and MPB

Figure 2.13 Estimated nitrogen inputs from sediments and human activities in 2000, and amount of nitrogen required by phytoplankton and MPB

28 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE The estimates in Figure 2.12 and Figure 2.13 are crude but, coupled with information presented earlier serve to illustrate that:

• In 1978, large nitrogen inputs from pipeline discharge were a major influence on chlorophyll levels; and • At present, sediment nutrient cycling and diffuse inputs from human activities (i.e. groundwater) appear to be the main factors controlling chlorophyll levels.

With the present level of understanding of nutrient cycling, it is not possible to predict to what extent further reductions in diffuse nutrient inputs to the Sound will affect overall chlorophyll levels. Available data suggest any response could be slow: Figure 2.9 and Figure 2.10 indicate that there has been little change in overall chlorophyll a levels in the Sound since inputs of nitrogen from human activities during summer dropped below about 100 tonnes (about 400 tonnes/year, in 1998). Further reductions in nitrogen inputs from human activities will, however, be important in reducing localised effects on water quality (Figure 2.11). Future changes in localised water quality may also occur within and between man-made structures (eg. harbours) due to changes in water circulation and reduced flushing times: these in turn could confine any existing nutrient inputs within a smaller area (as has happened in the Jervoise Bay Northern Harbour) and/or cause increased accumulation of organic matter in the sediments and increased sediment nutrient flux.

2.3.4 Marine sediments Water movement plays a major role in determining sediment type within Cockburn Sound. In deeper areas the sediments tend to be fine and silty, while shallower areas experience more wave and current action and so have sandy sediments (the finer particles are easily suspended and swept away). Deeper areas accumulate fine organic particles (e.g. dead plankton, faecal material), and so are naturally more organically enriched than shallower areas. The proportion of fine particles (the silt and clay fraction), in turn, influences the amount of naturally present metals: the more silt and clay, the higher the metal levels. The original source of a sediment (e.g. calcium carbonate from marine organisms versus material eroded from the land) also has a strong influence on natural levels of metals (calcium carbonate generally has far lower levels of metals than sediments eroded from the mainland.

Contaminants discharged to marine environments—and any increased production of organic matter due to nutrient enrichment—typically accumulate in the sediments, especially in sheltered, relatively deep areas such as Cockburn Sound. However, it is often difficult to determine how contaminated sediments are, and whether they pose a threat to marine life. Not only do different sediments have different ‘background’ levels of metals, but the silt+clay, organic matter and sulphur in sediments can bind contaminants in forms that can’t be taken up by marine life (i.e. the contaminants are not biologically available, or ‘bioavailable’). Thus, the same level of contamination may cause no effect in one type of sediment but severe effects in another.

In the 1976–79 Cockburn Sound Environmental Study, widespread contamination of sediments was found. A sediment study carried out as part of the SMCWS in 1994 found that contaminant levels had decreased significantly since the late 1970s, due to large reductions in wastewater discharges from industry. Metal levels found in 1994 were generally below DEP draft guidelines, apart from arsenic and mercury in some localised areas near industries or harbours. Very high levels of tributyltin (a highly toxic ingredient in antifoulant paints commonly used on large commercial vessels) were also found throughout the Sound, particularly near shipping facilities (see also

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 29 Section 2.4.5). Organic contaminants (e.g. pesticides, petroleum hydrocarbons, PCBs) were at very low levels in 1994, and were not considered cause for concern.

Available data (Table 2.3) also indicate that levels of organic matter and nitrogen in the sediments of the deep basin at the southern end of the Sound were higher in 1978 than in 1994, presumably due to the greater phytoplankton production. The remainder of the Sound appears to have been affected to a lesser extent, and presently differs little from Warnbro Sound, but there are few data for the shallow margins of the Sound.

Table 2.3 Changes in nitrogen concentrations in Cockburn Sound sediments

AREA NITROGEN IN SEDIMENTS (µg N/g dry weight of sediment) 1978* 1994** Cockburn Sound Southern basin 3,099 (2770–3,304) (6,600?)*** 2,448 Central basin (20 m) 1,792 (1036–2,436) 1,708 (1,180–2,004) Northern basin (20 m) 1,344 (812–2,044) 1,624 Eastern flats (<10 m) 896 673 Warnbro Sound Central basin (20 m) - 1,624 (1497–1,751) Central basin (16 m) - 800 * From Chiffings, 1987 ** From Bastyan and Paling, 1995 *** One site of the four sites measured had an exceptionally high value of 6,600 µg N/g dry weight of sediment

In 1999 there was a survey of contaminant levels in sediments at a number of SMCWS sites, using the same sampling techniques and analytical methods (DAL, 2000). The results of the 1999 survey for metal levels in Cockburn Sound sediments—and Warnbro Sound sediments as an example of an non-degraded environment—are shown in Table 2.4 along with the DEP’s 1994 data for the same sites. Organic contaminants were also measured, but were below detection limits (similar to the DEP’s 1994 results) and so are not shown.

Differences between the 1994 and 1999 surveys have to be interpreted with some care, as natural sediment variability is. Also, when metal level are near analytical detection limits (as is the case for cadmium, mercury, copper, and nickel at many sites), values within 5–10 times of the detection limit can be unreliable.

The two most striking differences between 1994 and 1999 are the apparent declines in arsenic and TBT levels. These apparent improvements may be real, but values in 1994 may have been elevated due to analytical errors as these two substances, particularly TBT, are notoriously difficult to analyse. What can be concluded is that levels of arsenic (and all other metals) in Cockburn Sound sites are well below the national ‘Interim Sediment Quality Guidelines’ (ISQGs) for the protection of marine ecosystems (also shown in Table 2.4), and TBT contamination is less than indicated by 1994 results. In relative terms, Jervoise Bay and Careening Bay were the most contaminated sites, particularly with TBT and, in the case of Careening Bay, with copper.

The 1999 survey also involved preliminary attempts to determine what natural levels of metals in Cockburn Sound sediments should be, based on data for a range of uncontaminated sites in adjacent waters. This was done for chromium, copper, lead, nickel and zinc. Results indicated that there was lead contamination near areas of shipping activity, and widespread zinc contamination throughout the Sound.

30 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Table 2.4 Sediment contaminant levels in 1994 sediment survey (DEP, 1996) and 1999 sediment survey (DAL, 2000)

DEP SITE CONTAMINANT* CODE Arsenic Cadmium Chromium Copper Mercury Nickel Lead Zinc TBT** SITE AREA ISQG-Low 20 1.5 80 65 0.15 21 50 200 5 1994 1999 1994 1999 1994 1999 1994 1999 1994 1999 1994 1999 1994 1999 1994 1999 1994 1999 Owen Anchorage 0401 4.0 2.5 0.6 <0.1 11.0 18 0.8 4.0 1.9 <0.1 4.3 1.3 5.0 <1.0 1.8 1.1 4.9 <1 Owen Anchorage 1310 <0.5 1.1 <0.2 <0.1 0.6 11 0.4 3.0 <.05 <0.1 1.6 1.4 1.4 1.5 1.0 2.6 3.7 <1 Jervoise Bay marina 1530 9.5 2.7 0.8 <0.16.21113150.20 <0.1 5.6 4.0 9.5 8.7 16.0 28.0 342 29 Cockburn Sound, north basin 3000 51.0 2.6 0.6 <0.1 14.0 19 3.7 6.0 0.05 <0.1 8.1 5.8 15.0 7.6 19.0 24.0 12.9 <1 Alcoa jetty 3210 74.0 3.0 0.3 0.09 11.0 13 7.1 8.4 0.05 0.07 5.6 4.9 11.0 9.4 16.0 25.0 1171 <1 Cockburn Sound, central basin 4000 64.0 2.5 0.7 0.11 19.0 25 4.7 7.8 <.05 <0.1 9.6 8.2 17.0 7.9 17.0 25.0 10.7 15 James Point 4010 9.5 1.5 <0.2 0.17 2.4 8.4 2.1 1.7 <.05 <0.1 3.1 1.1 5.3 <1.0 5.5 2.6 19.5 <1 CBH jetty 4500 68.0 3.8 0.6 0.32 21.0 27 7.6 12 0.16 0.12 11.0 12.0 23.0 11.0 25.0 35.0 22.7 <1 Cockburn Sound, southern basin 4800 75.0 4.9 0.4 0.29 19.0 29 8.2 11 0.06 <0.1 12.0 12.0 24.0 11.0 30.0 36.0 29.3 <1 Mangles Bay 5020 <0.5 2.0 <0.2 0.13 <0.2 10 0.2 4.1 <.05 <0.1 1.1 2.4 2.4 2.4 0.8 8.6 5.9 <1 Careening Bay*** C430 4.0 6.3 0.6 0.16 5.2 23 0.8 60.0 0.05 <0.1 4.2 7.2 6.4 30 1.7 67.0 65.9 190 Warnbro Sound shallows WS12 7.5 0.8 0.8 <0.1 5.7 13.7 1.0 3.9 <.05 <0.1 4.9 1.9 5.4 0.8 1.5 1.7 13.7 <1 Warnbro Sound basin WS27 3.5 8.2 <0.2 <0.1 <0.2 14.3 0.5 2.3 <.05 <0.1 1.2 2.6 1.7 3.9 1.5 6.0 2.7 <1 * 1999 values of greater than ten-fold difference to 1994 values are shaded light grey, values greater than the ISQG-Low values are shaded dark grey. All data in µg/g dry weight of sediment, unless otherwise stated. ** data in µg/g *** comparisons not valid as a slightly different site in deeper water was used in the 1999 survey

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 31 It is important to distinguish between the terms ‘contamination’ and ‘pollution’, which have carefully defined meanings. Contamination is the presence of a substance in the environment due to human activities, and pollution is when the substance is at levels sufficient to cause adverse environmental effects. The results of the 1994 and 1999 sediment surveys indicate some lead and zinc contamination in Cockburn Sound, but values were still well below national guidelines. The only substance at pollution levels was TBT, notably in Jervoise Bay and Careening Bay.

2.3.5 Marine flora The marine flora of Cockburn Sound include seagrasses, seagrass epiphytes, phytoplankton and the microphytobenthos (MPB, microscopic algae similar to phytoplankton, but which live on and in the seabed). There are also macroalgae (seaweed) on small patches of reef in the Sound, while an unknown amount of drift algae from reefs outside the Sound enters via tidal currents through the Causeway, and via north-west storms at the north end of the Sound, and accumulates in the deep basin. These aquatic plants provide the basis for food webs in the Sound.

The distribution of aquatic plants can be simply described in terms of the type of benthic (i.e. seabed) habitat. The distributions of seagrass, sand, reef and silt habitats were accurately mapped in 1999 (DAL et al., 2000), and are shown in Figure 2.14: phytoplankton and MPB occur throughout the Sound.

Seagrasses The historical loss of seagrass in Cockburn Sound documented in the 1976–79 Cockburn Sound Environmental Study has recently been re-analysed using the latest mapping techniques (DAL, 2000). The pattern of loss found in the earlier study has been confirmed: in 1967 seagrass was widespread in waters less than 10 m deep (Figure 2.15), and much of the seagrass on the eastern flats of the Sound was lost between 1967 and 1972. Between 1972 and 1982 further losses occurred on Southern Flats, and on the eastern shore of Garden Island in Careening Bay and around the Armaments Jetty. Seagrass losses on Southern Flats occurred after 1972, and appear to be more linked to sediment movement caused by the construction of the Causeway. The losses in Careening Bay and around the Armaments Jetty were due to naval development (dredging). Additional small-scale losses (1.8 ha) have occurred in Mangles Bay due to boat moorings (mooring chains ‘scythe’ seagrass as the boats swing round). There has been little loss since 1982 except for small areas on the eastern shore of Garden Island. There have also been several reports5 of healthy clumps of seagrass on the eastern flats of the Sound, in areas where the historical dieback took place, although these are not apparent in the mapping (aerial photograph resolution does not detect clumps of seagrass less than 2 m in diameter, and patches less than 30 m2 are not presented in maps).

The total area of seagrass within the CSMC boundary has declined from 2,821 ha in 1965/676 to 632.3 ha in 1999 (Figure 2.15). These figures differ from those reported in earlier exercises (Cambridge, 1979; DEP, 1996; DAL et al., 2000) as each refers to a different study boundary (note that the CSMC boundary excludes much of Parmelia Bank).

5 Dr Eric Paling, Environmental Sciences, Murdoch University. Dr Helen Astill, Aquatic Ecologist, D.A. Lord & Associates Pty Ltd. 6 Aerial photos from slightly different years sometimes had to be used to compile images for the area within the CSMC boundary (see also Figure 2.15)

32 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE HOLDING PAGES (X2) FOR A3 FIGURE

Figure 2.14 Benthic habitats in Cockburn Sound

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 33 Second holding page for figure 2.14 (back of A3 figure)

34 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE HOLDING PAGE

Figure 2.15 Historical sequence of seagrass dieback in Cockburn Sound

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 35 The massive loss of seagrass on the eastern flats from 1967 to 1972 has been attributed to nutrient enrichment effects, as explained earlier in Section 1.2. During work done for the 1999 mapping, information was found to suggest that while nutrient enrichment was undoubtedly a major cause of seagrass loss, there were other stresses on seagrasses at that time. The following dates and activities are noted:

• 1966: Nutrient-rich discharge commenced from the Woodman Point wastewater treatment plant; • 1969: Nutrient-rich discharge commenced from the KNC; • 1967: Discharge of large amounts of gypsum from CSBP; • 1968–70: Dredging of the Stirling and Callista Channels and turning basins, and dumping of dredge spoil over a large area about 1 km north-west of the Alcoa jetty (note: dumping of dredge spoil would have smothered seagrass, and dredge spoil dumping creates far more turbidity than dredging itself); and • 1968–70: Intensive scallop dredging of the Sound.

The DEP have an ongoing seagrass monitoring program that includes annual surveys of seagrass health, carried out by Edith Cowan University. The results of the 1998, 1999, 2000 and 2001 surveys, coupled with the 1999 mapping described above, indicate no further deterioration of the health of surviving seagrass meadows, and no significant losses related to water quality. There are, however, some ongoing concerns about the health of seagrass in Mangles Bay as the annual surveys show low shoot densities, high epiphyte loads and turbid water (due to suspended organic material) compared to other sites in Cockburn Sound. The greater stress on seagrass in this area appears to be due to increased retention of organic matter (which may be due to the Causeway) (Lavery7, pers. com.).

Reefs There are patches of reef along the eastern shore of the Sound between Challenger Beach and the Jervoise Bay northern harbour, and isolated hummocks on the eastern flats, mainly along the eastern fringe (Figure 2.14). The shoreline reefs are carry mainly brown algae (kelps and Sargassum),while on the reefs further offshore red algae are more common. Green algae (Ulva, Cladophora) are also common, and some of the reefs have patches of coral, including the reef-building species Flavites (Halpern Glick Maunsell, 1997).

Phytoplankton and MPB Phytoplankton levels, as measured by chlorophyll a levels, were described in Section 2.3.4. There has been no study of MPB in Cockburn Sound.

The species of phytoplankton present in Cockburn Sound were studied in 1978 by Chaney (1978), and between 1992 and 1994 as part of the SMCWS (Helleren and John, 1995). There are over 300 species present in the Sound, the four main groups being diatoms (Bacillariophyta), dinoflagellates (Dinophyta), silicoflagellates (Chrysophyta) and blue-green algae (Cyanophyta).

Diatoms typically predominate in local coastal waters, yet Helleren and John (1995) found that in both Cockburn and Warnbro Sounds there was a marked dominance by silicoflagellates (up to 95% of cells present) in autumn/winter, particularly the species Dictyota octonaria. This differed to earlier findings by Chaney (1978), when

7 Dr Paul Lavery, Senior Lecturer, Department of Environmental Management, Edith Cowan University

36 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE unidentified ‘Chlorophytes’ dominated the autumn/winter period. The dominance of silicoflagellates in the early 1990s caused concern because a similar species in northern European waters is associated with broad-scale nutrient enrichment. However, a follow-up study in 1999 found that silicoflagellates were present, but at far lower levels than in 1992 to 1994. A tentative explanation for the presence of the silicoflagellates between 1992 and 1994 may be that an unusually long ENSO event (El Nino/Southern Oscillation) occurred from 1990 to 1994, and so coastal water levels were low and the southwards flowing Leeuwin Current was weak. This may have allowed southern waters to move up the coast more than usual, along with the silicoflagellates (which are a cool water species), which subsequently flourished in the slightly nutrient-enriched conditions (Stuart Helleren8 pers. com.).

A number of species of dinoflagellates have been found in Cockburn Sound that are—if present in shellfish or fish—potentially harmful to human health, but all the species identified are widespread in local coastal waters, including Warnbro Sound. Occasionally, the blue-green algae Oscillatoria erythraea (Trichodesmium)—which can cause skin irritations to swimmers—appears as surface slicks in Cockburn Sound (as in autumn 2001). This species often blooms in offshore waters up and down the south-west coast of WA in late summer/early autumn (when conditions are calm), and sometimes drifts into nearshore areas.

At present, the only ongoing studies of phytoplankton species are for the Jervoise Bay Northern Harbour (as part of the Department of Commerce and Trade’s monitoring commitments), and by the mussel aquaculture industry around their lease site at Southern Flats and the Kwinana Grain Jetty. Potentially toxic species have been detected by both monitoring programmes but, to date, subsequent testing has established that the all species involved were non-toxic varieties.

Implications of seagrass losses and increased phytoplankton levels to food webs and nutrient cycling in Cockburn Sound The loss of seagrass and increase in phytoplankton levels in the Sound has dramatically altered plant production patterns. Estimated changes in plant production since the 1970s are shown in Table 2.5, and the amount of nitrogen used in that plant production in Table 2.6. The estimates in these two tables involve an number of assumptions (documented in Appendix A), are necessarily crude, and exclude the (unknown) role of reef algae entering the Sound. What Table 2.5 does show is a switch from co-domination by seagrass meadows and phytoplankton/MPB to domination by phytoplankton/MPB. The amount of nitrogen used by plants also increased greatly in the 1970s, as phytoplankton/MPB—which need lots of nitrogen—were able to grow due to the large nitrogen inputs at that time (Table 2.6). The tables also suggest that total plant production today is less than in the 1950s, but phytoplankton/MPB production and nitrogen use is still higher than in the 1950s.

Table 2.5 Estimated changes in plant production in Cockburn Sound since the 1950s

PERIOD PRODUCTION (tonnes carbon/year) SEAGRASS SEAGRASS PHYTOPLANK- TOTAL EPIPHYTES TON AND MPB* 1950'S 11,700 3,100 13,800 28,600 1978 2,250 600 25,300 28,150 PRESENT DAY 2,250 600 16,000 18,850 Microphytobenthos, i.e. microscopic algae growing on and in sediments, as opposed to phytoplankton which float in the water.

8 Stuart Helleren, Dalcon Environmental

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 37 Table 2.6 Estimated changes in nitrogen used by plants in Cockburn Sound since the 1950s

PERIOD NITROGEN USE (tonnes nitrogen/year) SEAGRASS SEAGRASS PHYTOPLANK- TOTAL EPIPHYTES TON AND MPB* 1950'S 470 120 2,120 2,710 1978 90 20 3,840 3,950 PRESENT DAY 90 20 2,790 2,900 Microphytobenthos, i.e. microscopic algae growing on and in sediments, as opposed to phytoplankton which float in the water.

The implications of these changes to the food web have yet to be investigated. Within local coastal waters, studies have established that food transfer is via an algae invertebrate fish pathway, whether the algae is seagrass epiphytes, reef algae, phytoplankton or MPB. Little seagrass production appears to enter the food web. This is because seagrass leaves are very seldom grazed, being low in protein and—unlike algae—containing unpalatable phenols and a lot of structural material including fibre (cellulose and lignin) (Klumpp et al., 1989). The majority of seagrass material becomes detritus and undergoes bacterial decomposition: during this process a high proportion (90—99%) of seagrass carbon is lost as respired carbon dioxide. In contrast, seagrass epiphytes, MPB and phytoplankton are grazed and so enter the food web directly. On this basis, the estimated plant production presently available to support the food web in the Sound (epiphytes+phytoplankton+MPB) differs little to that in the 1950s (and in fact was higher around 1978). However, species of fauna that prefer seagrasses as a physical habitat have obviously been disadvantaged.

If further significant declines in plant production occur in Cockburn Sound (due to ongoing reductions in nutrient inputs from human activities, and declines in sediment nutrient reservoirs; see below), declines in the populations of fish, crustaceans and shellfish may also result, notably those species that use the Sound for part or all of their life cycle. Effects on species of fish and crustaceans that pass through the Sound on their way to other areas would obviously be far less, and would be difficult to predict.

The loss of seagrass has also changed the nutrient-cycling processes in Cockburn Sound, and these, in turn, may affect what can be achieved with management of nutrient inputs from human activities. An attempt to explain the nutrient cycling changes from the 1950s to the present using a conceptual model is presented in Figure 2.16, Figure 2.17 and Figure 2.18. These diagrams are not meant to be taken as definitive, but rather as a starting point for further discussions to decide on an agreed conceptual model of nutrient cycling in Cockburn Sound.

When extensive seagrasses were present on the eastern margin in the 1950s, benthic nutrient cycling was dominated by the meadows themselves, and phytoplankton levels would have been low. There would have been little nutrient release from the sediments to the water column (due to the presence of seagrass roots), and much of what was released would have been taken up by seagrass leaves and/or epiphytes (Figure 2.16).

With the loss of seagrass meadows and greatly increased phytoplankton levels in 1978, not only were sediments enriched on the eastern margin and in the southern part of the deep basin (which would have led to more frequent periods of low oxygen in basin waters), but nutrient inputs (from both human activities and sediment release) would have rapidly fueled new phytoplankton growth (Figure 2.17).

38 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Figure 2.16 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 1950

Figure 2.17 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 1978

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 39 Figure 2.18 Conceptual diagram of nutrient cycling processes in Cockburn Sound in 2000

In 2000/2001, nutrient inputs from human activities are far less than in the 1970s, but nitrogen inputs—whether from human inputs or sediment release—are potentially more directly available for phytoplankton growth than when seagrasses were present. Even if nutrient inputs from human activities today were as low as in the 1950s, the absence of Posidonia meadows means it is uncertain whether phytoplankton levels on the eastern margin would be as low as in the 1950s, due to both the legacy of enriched sediments and the potentially more direct availability of nutrients to phytoplankton. The role of MPB in nutrient cycling (both on the eastern margin and in the deep basin) is an unknown factor here: providing they receive sufficient light, MPB may replace part of the role of seagrasses in reducing sediment nutrient flux to the water column. Obviously there are a variety of factors to be considered when predicting future scenarios, including reductions in nutrient inputs from human activities, the persistence of enriched sediments, seagrass re-growth (and what species re-grow), the role of MPB, water clarity, and changes in water circulation due to further developments.

2.3.6 Marine fauna The fauna of Cockburn Sound have been studied less regularly and extensively than the flora. This is partly because faunal studies are time consuming and expensive, and partly because results are often very difficult to interpret due to the considerable natural variations that occur in fauna populations.

Zooplankton Zooplankton in Cockburn and Warnbro Sounds were studied from 1992 to 1994 as part of the SMCWS, and were found to be typical of temperate coastal regions, apart from large blooms of radiolarians during late winter and early spring (DEP, 1996). As for silicoflagellates, there was some indication that the radiolarians were associated with cooler waters (DEP, 1996), and so their presence may also be linked to the ENSO event from 1990 to 1994 (see Section 2.3.5).

40 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Zooplankton in Cockburn Sound 1992 to 1994 were about twice as abundant as zooplankton in Warnbro Sound, presumably in response to the greater food supply (phytoplankton).

Invertebrate fauna The benthic invertebrate fauna of the deep basin have been studied in 1978 (as part of the 1976–79 Cockburn Sound Environmental Study) and 1993 (as part of the SMCWS). The deep basins of Cockburn Sound, Warnbro Sound and Owen Anchorage contain fine organic-rich silts due to accumulation of detritus from surrounding areas, and have species of flora and fauna that, to date, have been found nowhere else on the central west coast of Western Australia (Wilson et al., 1978).

The 1993 survey of benthic invertebrates found that more species were present, and in greater numbers, in the northern half of the Sound compared to the southern half. More species were found in the northern half of the Sound in 1993 compared to 1978, yet the reverse was found for the southern half of the Sound. In 1993, the bivalve Solemya—which prefers low oxygen conditions—was also found in the southern half of the Sound.

It is difficult to interpret the spatial patterns in 1993. The southern end of the Sound has sediments with a higher proportion of fine particles, more nutrients and more frequent periods of low oxygen than the northern half. These are all factors that influence benthic invertebrate populations, and is the explanation favoured by Chalmers (1993) for the differences found. Elevated metal levels in the sediments of the southern half of the Sound have also been suggested as a possible explanation (DEP, 1996), although metal levels are well below those typically associated with adverse effects. Differing recruitment of fauna (i.e. settling out of juvenile or larval stages in plankton) can also cause large differences between years. For example, the bivalve Solemya found in the 1993 survey was not present in a later survey by Glover and Taylor (1999).

Two acknowledged marine pests have also been found in the benthic fauna of Cockburn Sound: the European fan worm Sabella cf. Spallanzanii, and the Asian date mussel Musculista senhousia (see Section 2.4.6).

The SMCWS included survey of contaminant levels in mussels in 1991 and 1994. Mussels are particularly useful for detecting very low levels of contaminants in seawater because they feed by filtering the water column, and retain all the contaminants present. The two surveys found that with one exception (TBT), levels of organic contaminants were either below detection limit or (in the case of the pesticide DDT) very low. In contrast, TBT contamination was widespread (see also Section 2.4.4).

Levels of cadmium, chromium, lead, mercury and nickel in mussels were below detection limits at all sites. Concentrations of aluminium, arsenic, copper, iron, manganese and zinc were detectable, but below Australian and New Zealand Food Authority (ANZFA) guidelines. All metals were present at lower levels than found in an earlier study by Chegwidden (1978), and this was attributed to the large decreases in contaminants that had occurred. In relative terms, zinc was more elevated than other metals (although still below ANZFA guidelines), which supports the results in Section 2.3.4 suggesting that zinc levels are elevated in Cockburn Sound sediments.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 41 Fish Dybdahl (1979) estimated that there were about 130 species of fish and 14 large crustacean and mollusc species in Cockburn Sound. Fisheries WA9 have provided the following list that indicates (but is not limited to) the commercially/recreationally important species known to frequent various habitats in the Sound:

• Open (deep) water. Snapper, pilchards, bonito (also dolphins, seals and penguins). • Shallow water with sandy seabed. Whiting, juvenile King prawns, anchovies, blue sprat, whitebait. • Seagrass meadows. Leatherjackets, wrasse, crabs, herring. • Jetties and groynes. Herring, yellow tail, scad, trevally, samson fish, mussels.

Earlier work by Penn (1977) also suggests that the deep basin is an important habitat for whiting, squid, cuttlefish, butterfish, sampson fish, sand skipjack, crabs and snapper.

There is a lack of detailed studies on fish nursery areas within the Sound. Larval fish communities in seagrass meadows were studied as part of the SMCWS (Jonker, 1993), but there is little information on other habitats. It was found that meadows in Mangles Bay had similar species but significantly greater numbers of larvae than meadows off eastern Garden Island. This was attributed to greater food supply (i.e. higher phytoplankton levels), increased shelter due to the higher epiphyte loads, and greater retention of larvae due to the calmer waters of Mangles Bay compared to the Garden island site.

Although there is little information on fish nursery areas within the Sound, the breeding success of the species listed above would be affected by adverse impacts on their feeding grounds. The opinion of Fisheries WA is that both feeding areas and nursery areas are important in affecting fish populations, and that the whole of Cockburn Sound is significant as a fish nursery/habitat.

Other recent fish studies include work by Curtin University of Technology on fish health using biochemical markers (biomarkers) that indicate exposure to contaminants. To date, biomarkers of hydrocarbon exposure have been found at all sites examined (the highest levels were not in Cockburn Sound, but adjacent to Fremantle Fishing Boat Harbour). This work is ongoing, and there is also a forthcoming study in Cockburn Sound examining DNA damage and stress proteins as fish biomarkers in response to contamination (Monique Gagnon10, pers. com.).

Marine mammals, reptiles and seabirds A resident population of bottlenose dolphins (Tursiops sp.) lives in Cockburn Sound, and has become a popular tourist attraction. About 180 animals have been identified as using Cockburn Sound, and approximately a quarter of these are adult females with calves, which is unusually high for dolphin populations (Donaldson11, unpublished data).

Loggerhead, Leatherback and Green turtles sometimes stray as far south as Cockburn Sound, but this is rare.

9 Provided by Eve Bunbury, Fisheries WA, after discussions with Fisheries WA personnel. 10 Dr Monique Gagnon, Research Fellow, Department of Environmental Biology, Curtin University. 11 Rebecca Donaldson, Ph. D. researcher at the School of Biological Sciences, Murdoch University

42 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE At least 12 species of seabirds are found in the Cockburn Sound/Warnbro Sound area, but as the eastern shores of Cockburn Sound are heavily developed, they are of far lesser importance as a nesting, feeding and roosting area than the Shoalwater Islands Marine Park and Garden Island.

A small colony of Little Penguins Eudyptula minor (maximum 50 adults) has been established in limestone walling at Careening Bay since at least 1986. Regular migratory birds utilising Cockburn Sound include the Fairy Tern Sterna nereis and Bar-tailed Godwit Limosa lapponica. Migratory birds that may utilise the Cockburn Sound on a transitory basis include the Great Egret Egretta alba, the Eastern Reef Egret Egretta sacra, White-bellied Sea Eagle Haliaeetus leucogaster, the Ruddy Turnstone Arenaria interpres, the Caspian Tern Sterna caspia and the Crested Tern Sterna bergii. Young Australasian gannets also tend to feed in the Sound until mature and then return to New Zealand (Bob Goodall pers. com.).

2.4 PRESSURES ON THE MARINE ENVIRONMENT

2.4.1 Ecosystem overview The main types of pressures on the marine environment of Cockburn Sound due to human activities are as follows:

• Physical alterations to the environment which cause direct or indirect habitat loss, effects on water quality or alterations to coastal processes; • Nutrient enrichment (which can also cause habitat loss); • Contaminant inputs; • Discharge of cooling waters; • Introduction of foreign marine species; and • Over-fishing.

In relative terms, it is the first two of the above pressures that have had the greatest impact on Cockburn Sound, especially when acting in concert. It was the cumulative impact of human uses of the Sound that caused the large-scale loss of seagrass meadows and deterioration in water quality in the late 1960s and early 1970s, notably the combination of nutrient-rich industrial discharge, nutrient-rich municipal wastewater discharge, construction of the Causeway, FPA dredging and RAN dredging.

A more recent example of cumulative impact is the alteration of circulation patterns due to harbour construction, combined with contaminated groundwater inputs, that have led to water quality problems in the Jervoise Bay Northern Harbour. Ongoing problems in predicting and managing sediment transport along the Sound’s beaches are also due to the cumulative impacts of shoreline and offshore structures and beach re-nourishment programs.

Nutrient inputs to the Sound have been reduced dramatically, but there remains the potential for reduced water quality on the eastern margin of the Sound due to altered circulation patterns and flushing characteristics associated with several large-scale developments that are either under construction (the Jervoise Bay Southern Harbour) or proposed (FPA Harbour and the James Point Private Port). There is little doubt that reduced flushing will result in lesser water quality within these large-scale harbour developments, but their potential for effects further afield (between-harbour, and in the broader Sound) remains unclear. Careful interpretation of effects will be

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 43 needed, as water quality within the Sound may be affected by regional events (e.g. ENSO events, unusually strong or unseasonal outflow from the Swan River), and local events such as enhanced nutrient release from deep basin sediments at the southern end of the Sound during extended periods of calm.

2.4.2 Physical alterations to the environment Physical alterations that have (or that will soon) cause direct or indirect habitat loss (seagrass meadow and shallow sand), effects on water quality and alterations to coastal processes in Cockburn Sound, are as follows:

• Building of the at Woodman Point and WAPET groynes off the tip of Woodman Point; • Spoil disposal at Woodman Point; • FPA dredging of shipping channels and turning basins, and disposal of dredge spoil; • RAN dredging for harbour development on Garden Island; • Construction of the Causeway; • Construction of BP’s offshore breakwaters at James Point; • Construction of the breakwaters and reclamation of waterfront for the Jervoise Bay Northern Harbour; • Reclamation of waterfront, and dredging associated with the Jervoise Bay Southern Harbour; • Boat mooring damage in Mangles Bay and eastern Garden Island; and • Shoreline/road stabilisation works at Challenger Beach.

2.4.3 Nutrient enrichment Nutrients entering Cockburn Sound due to human activities fall into two broad categories, ‘point’ sources and ‘diffuse’ sources, as follows:

• ‘Point’ sources - nutrient discharge from a focussed source, e.g. industry outfalls, sewage outfalls, spillage from jetties during loading/unloading, spills from shipping accidents; and • ‘Diffuse’ sources - nutrients from no clearly defined point of discharge, e.g. groundwater discharge, surface run-off from urban and rural areas (usually channelled into water body via stormwater drains or agricultural drainage channels), Swan River outflow, atmospheric fallout (nitrogen oxides from industry discharge and car exhaust fumes).

There are five industrial outfalls presently discharging into Cockburn Sound: Western Power (largely cooling water but some contaminants present), BP Refinery (largely cooling water, but small amounts of treated wastewater), Tiwest Joint Venture, Wesfarmers CSBP, and Millenium Chemicals. The amounts of nutrients entering the Sound from the five industrial outfalls are documented as part of DEP licence conditions for discharge. These are discussed in some detail in Section 5.3.1. In addition, the Water Corporation has two emergency outfalls off Woodman Point: the old domestic wastewater outfall (situated 1.8 km offshore from Woodman Point), and the Jervoise Bay outfall (situated inside the Jervoise Bay Northern Harbour, 180 m from the shore). Discharge from these outfalls is small-scale and infrequent, and has contributed less than seven tonnes since 1990, as shown in Table 2.7.

44 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Table 2.7 Summary of emergency overflows from the Woodman Point Wastewater Treatment Plant to Cockburn Sound since 1990

DURATION OF OVERFLOW LOADS TO COCKBURN SOUND DATE OVERFLOW VOLUME (TONNES) Suspended Total Total (Hours/Minutes) (ML) Solids Nitrogen Phosphorus Cockburn Sound outlet 1990 16/03/90 0.30 0.0005 <0.001 <0.001 <0.001 23/03/90 0.10 0.002 <0.001 <0.001 <0.001 12/05/90 0.24 2.145 0.257 0.116 0.021 1991 08/03/91 2.00 0.504 0.069 0.027 0.005 20/04/91 1.00 0.180 0.022 0.010 0.002 23/05/91 0.52 0.314 0.038 0.017 0.003 23/11/91 0.58 2.106 0.253 0.114 0.021 1993 06/03/93 3.23 5.700 0.684 0.308 0.057 19/06/93 1.00 0.200 0.024 0.011 0.002 1994 16/04/94 0.10 560 0.067 0.030 0.006 1995 08/08/95 1.26 8.160 0.979 0.441 0.082 20/10/95 6.00 3.875 0.465 0.209 0.039 1996 11/05/96 5.06 13.690 1.643 0.739 0.137 1997 29/01/97 7.30 18.025 2.163 0.973 0.180 1998 10-11/07/98 16.10 36.160 5.243 1.989 0.372 3–4/08/98 15.25 35.510 4.616 1.811 0.284 SUBTOTAL 127.1315 16.524 6.796 1.212 Jervoise Bay outlet 1995 20/10/95 0.20 1.140 0.137 0.062 0.011 SUBTOTAL 1.140 0.137 0.062 0.011 TOTAL 128.2715 16.661 6.858 1.223

Diffuse sources are much harder to estimate accurately, but the main contributors at present are industrial groundwater, and groundwater under agricultural land at Spearwood. Diffuse sources are largely due to catchment uses, and are discussed in detail in Section 3.3.

The role of past nutrient inputs in causing seagrass loss and poor water quality was discussed in some detail in Sections 2.3.3 and 2.3.5. Nitrogen inputs to Cockburn Sound from human activities have declined from an about 2,000 tonnes/year in 1978, to 1,080 tonnes/year in 1990, to ~300 tonnes/year in 2000. A breakdown of the major contributors in these three years is shown in Figure 2.19. Estimated inputs in 2000 were: groundwater 212.4 tonnes, industrial discharges 54.7 tonnes, ship loading spills 5.6 tonnes, surface drainage 4.3 tonne and atmospheric fallout 20.4 tonnes.

Groundwater discharges remain the main input of nitrogen to the Sound, and industrial sources (discharges plus groundwater) contribute about 75% of the total. The Kwinana Nickel Refinery is no longer the main contributor, and because industrial loads have decreased so much the relative contribution of rural groundwater is starting to become significant.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 45 N inputs in 1978 (Total ~2,000 tonnes/year) Atmosphere Groundwater 1% 9%

Others 9%

KNC/CSBP discharge 51%

Woodman Point WWTP discharge 30%

N inputs in 1990 (Total ~1,080 tonnes/year)

Atmosphere Jervoise Bay 2% groundwater 6% CSBP discharge 40% KNR groundwater 36%

BP refinery Others discharge 9% 7%

N inputs in 2000 (Total ~ 300 tonnes/year)

CSBP discharge 10% Atm os phere Other discharges 7% 9% Other GW 9% Ship spillage 2% Rural groundwater Surface waters 15% 1% CSBP Jervoise Bay groundwater groundwater 25% 24%

Figure 2.19 Estimated nutrient inputs to Cockburn Sound from outfall discharges; groundwater; surface water; atmospheric deposition; and spills from ship loading/unloading in 1978, 1990 and 2000 Note: The areas of the pie-graphs are proportional to their relative inputs. Excludes inputs from sediment nutrient release.

46 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE The potential importance of Swan River outflow as a nutrient source to Cockburn Sound is uncertain. Winter outflow from the Swan River typically carries between 250 and 900 tonnes of nitrogen (DEP, 1996), but it is difficult to know what proportion enters—and is retained in—Cockburn Sound. Chiffings (1979) notes that river outflow is generally considered to move out to sea and then north or south along the coast, but seldom into Owen Anchorage and even less so into Cockburn Sound. Regional water quality data supports this (DEP, 1996). Chaney (1978) also found that phytoplankton growth rates in winter were less than a third of rates at the end of summer (suggesting little increase in phytoplankton production due to Swan River nutrients), but this was at a time when nutrient inputs from human activities were much higher than at present. Now that nutrient inputs from human activities are much lower, the relative importance of Swan River outflow as a nutrient source to Cockburn Sound will be greater. Although Swan River outflow may still be minor source of nutrients in most years, it may provide a major input to the Sound in years of unusually large flow.

As noted previously, areas such as Cockburn Sound with a history of nutrient enrichment from point and/or diffuse sources can also have increased ‘stores’ of nutrients in their sediments. Release of these nutrients contributes to the symptoms of nutrient enrichment and can maintain those symptoms even after the original cause of the problem has gone. The nutrient stores in Cockburn Sound sediments have declined considerably since 1978 (see Section 2.3.4), but the extent to which sediment nutrient release has changed is unknown.

2.4.4 Contaminants

Metals and organic contaminants As for nutrients, contaminants entering Cockburn Sound due to human activities fall into two broad categories: point sources and diffuse sources. Contaminant loads from industrial point sources are documented as part of DEP licence conditions, but there are few data for diffuse sources (see Section 3.3).

The large decreases in contaminant discharges from industrial point sources since 1978 are shown in Table 2.8, and present discharges are discussed in more detail in Section 5.3.1.

Table 2.8 Estimated contaminant inputs from licensed industrial discharges to Cockburn Sound

YEAR CONTAMINANT INPUT (kg/year) Arsenic Chromium Copper Mercury Lead Nickel Zinc Oil 1978 unknown 2,065 3,809 105 3,259 571* 8,557 363,540 2000 34 1 600 2 16 79 1,077 4,547 * Probably an underestimate.

The data in Table 2.8 indicate that sediment contamination in the Sound is a legacy of past rather than current inputs.

Tributyltin Tributyltin (TBT) is the active ingredient in antifoulant paints that the majority of the world’s shipping fleet uses. TBT based paints are extremely reliable, offering up to five year’s protection against both the growth of organisms such as barnacles on ships’ hulls (that would otherwise slow a ship down due to increased drag, resulting in increased fuel consumption), and the spread of foreign marine organisms. TBT

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 47 based paints were also commonly used in WA on small (less than 25 m long) commercial and recreational boats up until about 1992.

TBT is highly toxic to a wide range of marine organisms, and can cause serious effects at extremely low concentrations. The classic symptom of TBT contamination is ‘imposex’ (development of male reproductive organs) in female snails, which can block egg release and make them sterile. TBT breaks down rapidly in marine waters but accumulates in marine sediments, and is the sediment contaminant of greatest concern to the DEP.

Many countries have partial or complete bans on the use of TBT based paints. In 1991 the WA State Government imposed a ban on the use of TBT on vessels less than 25 m long, and restricted its use to low-leaching paints on boats over 25 m.

The SMCWS included a 1993 survey of imposex in marine snails, and a 1994 survey of sediment TBT levels. The sediment survey found widespread contamination of Cockburn Sound sediments with TBT. Very high TBT levels were found next to ship berthing and ship maintenance facilities (DEP, 1996), along with 100% incidence of imposex in marine snails (Field, 1993). Many interstate and overseas studies have also found that slipways, drydocks and washdown yards (where boats are scraped down and repainted with antifoulant) are a major point source of TBT to the marine environment.

A further study on imposex in marine snails was carried out in 1999, and found a significant improvement in areas visited by recreational vessels less than 25 m long (e.g. Cottesloe to Ocean Reef, Rottnest Island), but not at sites adjacent to ports and other commercial shipping activities where vessels greater than 25 m long are berthed or serviced. In Cockburn Sound, 100% incidence of imposex was found at the four sites surveyed: three sites in the Jervoise Bay/Challenger Beach area, and one site at Colpoys Point near the naval berthing facility (Reitsema12, pers. com.). Therefore, although the 1999 sediment survey indicated greatly decreased levels of TBT at Jervoise Bay, they are still sufficient to cause imposex.

2.4.5 Cooling waters There are two cooling water discharges into Cockburn Sound: Western Power (about 1,600 ML/day) and BP Refinery (about 440 ML/day). These shoreline discharges cause some increase in temperature close to the outfalls (about 2°C) but this dissipates rapidly and effects are hard to detect after a couple of hundred metres. The discharges appear to have very little effect on marine biota.

2.4.6 Foreign marine organisms Cockburn Sound has been visited by international shipping since the 1830s, and has been a regular port of call for national and international vessels since 1954. Foreign marine organisms can enter WA waters via discharge of ships’ ballast water prior to loading cargo. Contaminated ballast water may be from international shipping, or ships from other Australian ports where foreign marine organisms are present (e.g. Port Phillip Bay, Hobart). Organisms attached to ships’ hulls may also fall off, or be scrubbed off during ‘in-water’ cleaning of hulls and propellers. In-water cleaning was allowed in Cockburn Sound until several years ago, but has since been banned by the FPA.

12 Tarren Reitsema, post graduate researcher at School of Public Health, Curtin University

48 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE A survey of introduced marine pests in FPA waters (including Cockburn Sound) was carried out in 1999 (CRIMP, 2000 unpublished) as part of a Australian port survey programme that was a joint initiative of the Australian Association of Port and Marine Authorities (AAPMA) and the CSIRO Centre for Research on Introduced Marine Pests (CRIMP), and supported by the Australian Ballast Water Management Advisory Council (ABWMAC). This programme was designed to provide information for a ballast water management decision system for Australian waters (see also Section 5.4.1).

Sites sampled in Cockburn Sound included all commercial and naval jetties. At least 18 exotic marine organisms have become established in local coastal waters (DEP, 1996; CRIMP, 2000 unpublished). Two ABWMAC targeted pest species have been recorded in Cockburn Sound: the European fan worm Sabella cf. Spallanzanii (throughout the Sound), and the Asian date mussel Musculista senhousia (Southern Flats). The European fan worm and Asian date mussel are prolific growers, and can out compete native species, affecting biodiversity. The CRIMP study indicated that these two pest species do not seem to be having this effect in FPA waters.

Other species recorded in Cockburn Sound that are either introduced or of unknown origin, but which are not significant environmental or economic threats include: the fish Tridentiger trigonocephalus, the bryozoans Bugula neritina, B. flabellata, Tricellaria occidentalis, Cryptosula pallasiana and Watersiproa subtorquata(?), the hydroid Tubularia raphi, and the ascidians Asidiella aspersa and Ciona intestinalis.

2.4.7 Commercial and recreational fishing Commercial and recreational fishing result in direct removal of target species of fish. Depending on the fishing method used, there can also be losses due to by-catch (non- target species). Other pressures include fuel spills; rubbish; loss of gear (nets, lines, hooks, sinkers etc); and habitat damage from propeller and hull scour, nets and anchors.

The fishing gear allowed in Cockburn Sound and the present level of fishing effort is not believed to be a major pressure on Cockburn Sound. The main management issue is likely to be the sustainability of the combined catches of commercial and recreational fishing as recreational fishing pressure increases. Pressures due to recreational fishing are discussed in more detail in Section 4.3, and commercial fishing in Sections 5.3.3 and 5.3.4.

Commercial fishing The level of fish harvesting from Cockburn Sound from 1977 onwards was estimated from WA Fisheries annual commercial fish catch data for Cockburn Sound Fisheries Block 9600. This area includes all waters within a line that extends from South Mole at Fremantle west to Stragglers Rocks, then through West Success Bank to Carnac Island to Garden Island, along the eastern shore of Garden Island and to John Point on the mainland (Penn, 1999). Although this area includes Owen Anchorage, most commercial fishing occurs within Cockburn Sound.

Annual commercial catches of finfish and molluscs (includes squid and octopus but excludes mussels), crabs, mussels and baitfish are shown in Figure 2.20. The mussel data are for wild harvest only: there are no data for before 1982 or after 1992 as fewer than 5 boats collected the catch, and Fisheries policy is to not release data under these circumstances. However, wild mussel catches before 1982 and after 1992 were extremely low.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 49 Annual commercial fish catches Baitfish 1800 Finfish/molluscs Crabs Mus s els 1500 Total 1200

900

600

300

Catch (tonnes live weight) Catch 0 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Year

Figure 2.20 Annual commercial fish catches in Cockburn Sound Fisheries Block 9600 since 1977 (excludes mussels from aquaculture)

The greater part of commercial catch until about the last three years has been baitfish (which feed on plankton). However, changes in the fisheries cannot be linked to changes in plant production in the Sound, as the former are due to many factors including market pressure, change in gear type and fishing effort, and recruitment effects.

Finfish catches (especially garfish catches) have been increasing since the 1970s, causing some concern to Fisheries WA. Conversely, catches of King George whiting, western sand whiting, squid and octopus have all declined in recent years. Reasons for the declines are not fully understood, but are thought to include environmental factors, fishing pressure and/or market considerations.

Mussel aquaculture in Western Australia began in Cockburn Sound in 1988 to overcome the declining catches of the wild capture fishery and to provide a more consistent source of product. The large majority of mussels now harvested from Cockburn Sound are from aquaculture. Mussel aquaculture is undertaken in Cockburn Sound, Warnbro Sound and Albany, and total harvests in the last two years have been 663 tonnes and 683 tonnes, respectively. Harvest data for Cockburn Sound area cannot be released due to commercial confidentiality, but a significant proportion of the harvest comes from Cockburn Sound.

Recreational fishing Cockburn Sound is very popular for recreational fishing. The main species caught are crabs, whiting (especially King George whiting), Australian herring, squid, garfish, trevally, dhufish, tailor and pink snapper (Sumner and Williamson, 1999). These are many of the species targeted by commercial fishers.

Data on recreational fishing pressure on Cockburn Sound were collected during a 12 month survey in 1996/97, and have been provided by courtesy of the Fisheries WA Research Division. During this survey, there were an estimated 12,083 boat trips in Cockburn Sound. The recreational catch for crabs was estimated as 18.8 tonnes (about 5.2% of the commercial catch of 360 tonnes). For finfish, catch weights were estimated for Australian herring (13 tonnes) King George whiting

50 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE (9 tonnes), whiting other than King George (7 tonnes), skipjack trevally (5 tonnes), tailor (3 tonnes) and garfish (2 tonnes), giving a combined catch of 39 tonnes13— about 65% of the commercial finfish catch of 60 tonnes (excluding baitfish) for the same period. In addition, 58,000 squid were caught by recreational boat fishers. As these data do not include shoreline recreational fishing, it is clear that the recreational finfish catch is of a similar magnitude to the commercial catch.

2.5 MANAGEMENT RESPONSES

2.5.1 Current management responses There are a number of national strategies that encompass protection for the marine environment. These include the National Strategy for the Conservation of Australia’s Biological Diversity (for the protection of biological diversity and maintain ecological processes and systems), and the National Water Quality Management Strategy.

The National Water Quality Management Strategy has set out a framework for the management of natural waters. As noted in Section 1.3, the NWQMS approach has been followed in the coordinated management framework currently being developed by the EPA and DEP for the protection of Perth’s coastal waters. The EPP being developed for Cockburn Sound is a part of that exercise, and the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ARMCANZ, 2001 due for imminent release) will play an important role in the development of some EQC.

The formation of the CSMC itself is a direct management response to the lack of coordination recognised in EPA Bulletin 907, which in turn is based on a recommendation of the SMCWS (DEP, 1996).

Management responses specific to land use (impacts on groundwater, surface water), social/cultural uses (recreational uses including fishing) and economic uses (industrial discharges, shipping, commercial fishing and tourism) are dealt with in Sections 3, 4 and 5 respectively.

Local government The boundary of the CSMC’s jurisdiction includes three local governments: the City of Cockburn, the Town of Kwinana and the City of Rockingham. Local governments play a key role in the management of coastal areas by zoning to separate incompatible uses, providing and maintaining suitable and safe recreational facilities and paths, and undertaking erosion control measures. The following information is noted:

• City of Cockburn: has a Coastal Management Strategy and a Coastal Works Plan that addresses coastline works, foreshore rehabilitation and reserve management. It has recently released its State of the Environment report, and is currently undertaking the development of its Local Agenda 21 Plan which is part of the City of Cockburn's overall Sustainable Development Strategy. It is also currently preparing an Environmental Management System to address all aspects of its business; • Town of Kwinana: has an Environmental Policy and a Coastal Management Plan. The latter is currently being updated in Kwinana’s Environmental

13 Data generated by Neil Sumner, Fisheries WA

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 51 Management Plan. Protocols for undertaking beach erosion controls have recently been modified to include greater stakeholder involvement and advice from relevant State Government department; and • City of Rockingham: has a Strategic Coastal Management Plan for all of its beaches (and forming the framework for all the individual management plans), which is currently being reviewed. It also has a List of Environmental Priorities, and has released its first (2000–2001) State of the Environment Report incorporating an Environmental Action Plan.

At present, environmental management and planning by each of the Councils proceeds—for the most part—on a case-by-case basis, and management approaches differ slightly. The three Councils do not, at present, follow any common or coordinated approaches or protocols for the various aspects of coastal management and planning, because none is available. However, the Western Australia Municipal Association has established a Coastal Management Advisory Group (for the whole State ) which aims to better co-ordinate coastal planning, and Cockburn, Kwinana and Rockingham are represented on that group. The three Councils also have a good communication network for environmental issues, and the Environmental Officers liase on issues which impact on the three Councils and/or Cockburn Sound. Thus, while each Council may formulated separate responses, they liase closely for proposals which may effect the broader region. All three Councils are also represented on the Cockburn Sound Conservation Committee, which offers a forum to address concerns from each of the Councils regarding proposals and impacts to Cockburn Sound. The councils are presently awaiting guidance from the CSMC’s EMP (all three councils are represented on the CSMC) before refining their own planning and management initiatives to be consistent with the EMP.

The boundary of the CSMC’s jurisdiction abutts Garden Island. The RAN has an EMP for Garden Island and HMAS STIRLING, and this is currently being revised to reflect and complement initiatives at the regional level. Defence is also currently investigating whether there are any localised impacts on seagrass on the east coast of the island due to groundwater contaminated by nutrients from its sewage farm (Wykes, pers. com).

Community groups Community groups such as Com-Net, CORKE, Cockburn Power Boat Association, RecFishWest, Kwinana Watchdog Group and the Conservation Council play a vital role as ‘environmental watchdogs’ and in raising community awareness about environmental matters. The long history of strong community interest in the environmental problems of Cockburn Sound also helped encourage the formation of the CSMC.

2.5.2 Gaps in the management responses The CSMC will overcome the main problem in previous management efforts, by attempting to implement a consistent and coordinated management approach across different levels of government, industry and community groups.

There has been some comment on the exclusion of Garden Island from the defined area under the jurisdiction of the CSMC, as it needs to be considered as much as the eastern coastal boundary in any environmental planning and management.

52 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 2.5.3 Gaps in information needed for management The EPA’s Bulletin 907 on strategic environmental advice for Cockburn Sound (EPA, 1998) noted that environmental decision-making was being made more difficult by key information gaps in four main areas:

• Hydrodynamics; • TBT inputs from shipping activities; • Nutrient cycling and algal blooms; and • Ecology (i.e. biological assemblages).

During compilation of this P-S-R report it was clear that the main information gaps to do with understanding and/or representing ecological processes within the Cockburn Sound remain unchanged. In particular, there is a need for:

• Additional data to improve modelling of a) water movement in Cockburn Sound and b) coastal processes in Cockburn Sound; • An agreed conceptual model of nutrient cycling in Cockburn Sound and the effects of nutrient inputs; and • An agreed method for evaluating cumulative impacts.

Each are discussed below.

Modelling of water movement in Cockburn Sound Bulletin 907 (EPA, 1998) was prepared largely in response to the potential impact of several large-scale harbour developments on water movement within the Sound, and the subsequent effects on water quality and ecology. Accurate predictions on water movement are thus essential as they underpin all subsequent predictions on water quality and ecology.

The fundamental hydrodynamic processes within Cockburn Sound are well understood, and are backed up by an extensive set of field data (e.g. water salinity, temperature, density; DEP, 1996, and references cited therein). However, this information is not sufficient to allow examination of effects on water quality and ecology within the Sound over time frames of up to several years (EPA, 1998) or to investigate site-specific processes at the small scale (<100 m). Bulletin 907 (EPA, 1998) identified the following information requirements:

• Effects of density stratification on circulation and mixing of contaminant and other materials; • Simulations for a far wider range of meteorological and seasonal conditions, assessed against appropriate field measurements; • Hydrodynamic simulations over ecologically meaningful time frames (up to several years); • Further data required to characterise the autumn period when long residence times of the bottom waters of the deep basin are of ecological significance; and • Estimation of turbidity in the Sound through use of a sediment mobilisation and transport model, appropriately coupled to a hydrodynamic model (note that this would also cover contaminants adhering to sediments).

Recent hydrodynamic modelling of Cockburn Sound has included the use of stratification to investigate development proposals (Cockburn, 2000; JPPL, 2001).

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 53 These simulations were undertaken over a wide range of meteorological conditions and assessed against field data collected during the autumn period. The following discussion addresses the remaining three requirements identified by the EPA (1998).

Seasonal circulation patterns due to wind and tides are relatively well understood and therefore well represented in models, but circulation due to forces that acts over yearly time-scales is less well understood (mainly horizontal pressure gradients and buoyancy effects). Effectively, this means that circulation during calm periods (generally autumn) is not well represented in models, nor are differences between years.

The current limitations of modelling are largely due to a lack of relevant field measurements, plus the inability of current computer resources to undertake long- term simulations. There is also a lack of field data to assess the influence of localised effects upon circulation. For example, it is widely recognised that the southern region of Cockburn Sound is sheltered from the predominantly southerly winds while the northern region is open to the full impact of these winds.

As noted previously, prediction of effects on water quality and ecology depend on predicted effects on water movement, and increasing demands are being placed upon models to aid environmental management. The ability of models to produce defensible results over the long term (seasonal, annual and inter-annual) is hampered by the lack of long-term field measurements. Field data collected over longer periods will also improve the present understanding of seasonal processes (e.g. what happens during calm periods).

Key data requirements are considered to be as follows:

• Long-term wave data. Minimum requirements are considered to be two wave measurement sites within Cockburn Sound (one in southern region, one in northern region) and one offshore (already in operation). This will be particularly useful in interpreting changes in sediment transport in the Sound and addressing the potential issue of sediment mobilisation; • Long term current meter deployments, also collecting temperature and salinity data, at the northern and southern entrances to Cockburn Sound, to use for model simulations of periods of up to several years; • Further salinity and temperature surveys, which should also be coupled with continuous profiling of vertical current structure, and which will also aid in the development and application of hydrodynamic models over time periods of several years; and • Sampling should be coordinated whenever possible with biological and ecological sampling programs.

With the ability to model at smaller scales (e.g. less than 100 m) localised effects such as groundwater discharges can also be resolved. Improved computer technology will also allow the refinement of wind patterns, bathymetry and friction. Models will need to incorporate information such as:

• Variations in winds in different parts of the Sound, and with time; • The effects on currents and waves of changes in ‘bottom friction’ as they pass over different types of seabed (e.g. seagrass, bare sand, rubble); and • Linkages between hydrological models (surface and groundwater) to determine the influence of freshwater inflows.

54 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Coastal processes Information from previous coastal studies of Cockburn Sound is spread over a wide variety of agencies with different time-frames for developments, different needs and agendas, and commercial arrangements. A general recommendation is for a study that collates all the existing information to establish a conceptual model of coastal processes within Cockburn Sound.

In particular, it is noted than an extensive data set of offshore beach profiles has been collected around Cockburn Sound by the Royal Australian Navy (RAN) between 1976 and 1990. These RAN data are the only set of continuous beach profile measurements collected within Cockburn Sound: analysis of these data and further surveying of these profiles would provide extremely valuable information. There are also a number of aerial photographic surveys that have been undertaken in the region and that could be used to examine shoreline movement. Many agencies have already undertaken localised analyses (e.g. Department of Transport, Maritime Division; DMH, 1992), and should be contacted to collate as much historical information as possible.

Further investigation of coastal landforms and processes needs to be centred on field measurement and wave modelling. The field measurements will improve understanding of coastal processes and lead, in turn, to improve modelling of those processes. Some of the key data required for coastal processes are the same as for water movement in the Sound. Key data requirements are considered to be as follows:

• Wave climate. Directional wave data inside Cockburn Sound needs to be collected at the same time as wave data outside Cockburn Sound. A relationship between wave data collected inside Cockburn Sound and outside (currently in operation) can be established for the purposes of calibrating and validating a numerical wave model (see also recommendations for water movement in Cockburn Sound). The FPA has a non-directional wave recorder at the entrance to the Stirling Channel, and although the data are generally unavailable for commercial reasons the FPA have indicated they would be happy to assist in this respect, given certain precautions; • Nearshore currents (see recommendations for water movement in Cockburn Sound); • Weather. The weather of the Perth coast is relatively well measured, but there are few specific data for the Cockburn Sound region. Nor has the variation of winds within Cockburn Sound been examined (see also recommendations on water movement in Cockburn Sound). It is noted that the RAN is presently establishing a full weather station at Careening Bay with several automatic reception sites around Garden Island, and as this is a joint exercise with the Bureau of Meteorology, data will be available to the public; • Variations in water level. Water level variations are an important contributor to the coastal processes within Cockburn Sound. Due to the low energy wave environment the beach widths are relatively narrow, and storm surges (rises in water level due to a combination of wave setup, wind setup and low atmospheric pressure) can cause significant erosion of higher areas of beaches. The effect of storm surges can be predicted using extreme water levels (e.g. 1 in 10, 1 in 50 and 1 in 100 year water level) from long term sea level records. Presently, a wave staff is in operation near the entrance to the Stirling Channel, and a similar instrument is located on Parmelia Bank. The staffs and data are

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 55 owned by the Fremantle Port Authority and the data record is approximately 4 years long; • Beach Profile Data. The extensive data set of offshore beach profiles collected by the RAN should be monitored and used in conjunction with wave modelling and shoreline movement plans to establish sediment transport over a variety of time scales (weeks to decades); and • Aerial Photography. Annual aerial photography is useful for examining the stability of the shoreline over long periods (5 to 10 years). Regular aerial photography is best undertaken at the end of summer when the beaches are most prograded and storm activity is unlikely to occur. The possibility of using the annual photography undertaken by the Department of Land Administration (DOLA) for preparation of the metropolitan street directory also needs investigating.

Nutrient cycling in Cockburn Sound and the effect of nutrient inputs Bulletin 907 (EPA, 1998) recognised the following information requirements for nutrient cycling and the ecology of Cockburn Sound:

• Nutrient cycling and algal blooms: More accurate estimates of nitrogen inputs from groundwater and how they vary seasonally; Estimates of sediment oxygen and nutrient fluxes throughout the Sound, and the role of vertical mixing in determining oxygen levels in the water; Water quality models to predict algal biomass, oxygen depletion and light attenuation; Improved knowledge (and incorporation into models) of feedbacks between ecological processes and nutrient cycling (e.g. the role of zooplankton and benthic filter feeders in controlling phytoplankton density and distribution); and Improved knowledge of dinoflagellate cyst distributions and conditions leading to germination. • Ecological: Data on the existing biological assemblages on the eastern margin, both within and beyond existing harbour areas; Improved understanding of implications of changes in water and sediment quality for distribution and function of biological communities; and Relationships between assemblages and local populations of fish and crabs, and the connections between these local populations and the fisheries.

The need for more accurate estimates of nitrogen inputs from groundwater and how they vary seasonally is discussed in Section 3.4.3, and the ability to model the movement of such inputs was discussed earlier. Research on conditions leading to dinoflagellate cyst germination is a highly specialised field, and is currently being undertaken by Dr Gustaaf Hallegraeff at the University of Tasmania.

The remaining information requirements distil into—or depend on—the need for an agreed conceptual model of nutrient cycling (particularly nitrogen): that is, the key processes affecting water and sediment quality, and the relative importance of those key processes. These processes will need to be determined before implications to the

56 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE distribution and function of biological communities and consequent effects on fisheries can be considered.

It is suggested that one useful starting point for further discussion is the simple conceptual model of nutrient enrichment presented in this document, which focuses on sediment nutrient cycling, water quality and phytoplankton/MPB growth. Other useful models are also available from the Port Phillip Bay Study (CSIRO, 1996) and the Moreton Bay Study (Dennison and Abal, 1999).

A key information gap is up-to-date data on sediment characteristics in Cockburn Sound, particularly the levels of nutrients, organic matter and chlorophyll a (the latter being an indication of MPB growth). This information, used in combination with generic relationships for recognised key processes available in the scientific literature (and data ranges that are likely to be applicable to Cockburn Sound) could be used to refine a conceptual model.

The outcome of the above process will be recognition of the key features controlling water quality in different parts of the Sound, and how to tailor management approaches accordingly. For example, characteristics of water depth, circulation, flushing, sediment nutrient cycling and proximity to nutrient inputs from human activities differ between the shallow regions (i.e. water depths less than 10 m) on the east and west of the Sound, the deep central basin, and the poorly flushed southern basin: these factors are pivotal in determining the water quality that can be attained in these four main areas, and how to get the best environmental return for management effort.

Cumulative impact assessment Cumulative impact occurs when the impact associated with an activity overlaps and adds to the impact from other activities. When multiple activities occur in a region, any one activity may result in an acceptable modification of environmental conditions, but the changes associated with all activities may be unacceptable. As noted in Section 2.4.1, the major environmental problems in Cockburn Sound (past and present) are due to cumulative impacts.

Cumulative impacts need to be assessed over a variety of spatial scales (immediate area of proposal, adjacent areas, and the whole of Cockburn Sound), and short-term, medium-term and long-term effects considered. It will also be important to recognise the increasing levels of uncertainty inherent when predicting effects on water quality and ecology due to changes in circulation and flushing times: effects on fauna depend upon effects on water quality and sediment quality, which in turn depend on changes in circulation and flushing times. Predictions at each level have their own inherent uncertainty as well as incorporating the uncertainty of the preceding step, and these will have to be acknowledged in any interpretations of potential effects (e.g. by quoting ranges as well as ‘most likely’ values). Assessment of cumulative impacts in Cockburn Sound is also complicated by the legacy of impacts due to past discontinued practices: the Sound is not in a pristine state.

An agreed and consistent basis for cumulative impact assessment is needed to assess the potential impacts of future developments on the marine environment of Cockburn Sound. It is suggested that investigation of the cumulative impact of development within Cockburn Sound uses a modelling approach (with a hydrodynamic model as the basis), to allow a wide range of processes and scenarios to be investigated and compared relatively quickly. A potential framework for cumulative impact assessment is given in Table 2.9, and is offered as a basis for further discussion.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 57 Monitoring programmes There are a number of monitoring programmes currently in place that it is anticipated the CSMC will become responsible for. These monitoring programmes are listed below, with suggestions for additional work:

• The DEP’s monitoring of seagrass health every year and seagrass distribution every three years. It is suggested that monitoring of seagrass health be expanded to include sites along eastern Garden Island, as protecting remaining healthy meadows of seagrass in the Sound is a high priority. A survey of the eastern flats (the main area where the historical dieback of seagrasses occurred) is warranted, to investigate several reports on the existence of patches of healthy seagrass. The possibility of natural recolonisation of seagrass in this part of Cockburn Sound needs to be checked; • The KIC’s water quality surveys of eight sites once a week from December to March inclusive. It is suggested that the existing sites be reviewed and added to, and that fluorometry runs be undertaken to better characterise the spatial patterns of chlorophyll in the Sound. It is also recommended that light sensors and artificial seagrasses (a means of measuring epiphyte growth) be deployed in the Sound at several key locations to check on the conditions for seagrass growth. It is anticipated that results of this monitoring will be compared against the EQC set in the EPP for Cockburn Sound; and • A survey of contaminant levels in sediments at a selection of previously monitored sites should be carried out every five years, to confirm that there is no long-term accumulation of contaminants.

58 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Table 2.9 Potential framework for cumulative impact assessment strategy

ISSUE SPATIAL SCALE TIME SCALE ASSESSMENT TOOL(S) LEVEL OF INVESTIGATION LIKELY SIGNIFICANCE OF AND FOLLOW UP IMPACTS (days, months, years) (low, medium or high priority) (low, medium or high) Circulation and Within proposal area D-M-Y - Calibrated hydrodynamic model residence time Areas adjacent to proposal D-M-Y Within Cockburn Sound M-Y+ Marine water Within proposal area D-M - Calibrated hydrodynamic model quality Areas adjacent to proposal D-M - Water quality information collected to date Within Cockburn Sound M-Y+ - Conceptual model of nutrient cycling Sediment quality Within proposal area Y+ - Organic build up: zones of maximum residence time Areas adjacent to proposal Y+ and lowest current velocities in hydrodynamic model Within Cockburn Sound Y+ - Conceptual model of nutrient cycling - Sediment quality information collected to date Benthic habitat Within proposal area Y - Analysis of historical information Areas adjacent to proposal Y - Detailed habitat map Within Cockburn Sound Y Coastal processes Within proposal area M-Y+ - Analysis of historical data Dependent on proposal Dependent on proposal and littoral drift Areas adjacent to proposal M-Y+ - Calibrated hydrodynamic model (including impacts Within Cockburn Sound M-Y+ - Coastal process model on the seabed) Dunes Within proposal area Y+ - Analysis of historical information Areas adjacent to proposal Y+ - Site survey and assessment Within Cockburn Sound Y+ Terrestrial Within proposal area Y - Analysis of historical information vegetation Areas adjacent to proposal Y - Site survey and assessment Within Cockburn Sound Y Groundwater Within proposal area M-Y+ - Collation of historical data and desktop assessment quality Areas adjacent to proposal M-Y+ - Proponent’s commitment on groundwater impacts Within Cockburn Sound M-Y+ Surface water Within proposal area M-Y+ - Collation of historical data, desktop assessment quality Areas adjacent to proposal M-Y+ - Proponent’s commitment on drainage design Within Cockburn Sound M-Y+

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 59

3. LAND COMPONENT

3.1 OVERVIEW Land uses within the Cockburn Sound catchment includes urban areas, defence, industry, agriculture and conservation. The main way that these land uses affect the environment of Cockburn Sound is by contamination of groundwater and surface water that flows into the Sound. It has been estimated that there are potentially more than 70 groundwater contaminant plumes within the Kwinana area alone. Emissions from motor vehicles and industry also contribute to contaminant inputs to the Sound via atmospheric fallout.

The varying degrees to which the main land uses contribute contaminants to the Sound are discussed in this section. A brief description of the landform, flora and fauna of the coastal fringe is also provided.

3.2 THE LAND AND ITS USES

3.2.1 Coastal fringe landform Earlier in this report (Section 2.1) the Tamala Limestone (TL) of the Spearwood Ridge was identified as the underlying formation of the present coastline of Cockburn Sound. The Tamala Limestone comprises an upper layer of pale yellow medium to coarse grained sand that has decomposed from the deeper limestone, which in turn is a pale yellow/brown variably cemented fine to coarse grained lime sand with shell debris (calcarenite). It is overlain by varying thicknesses of Safety Bay Sand (SBS), which is a calcareous medium grained quartz sand with shell debris of shallow marine, coastal plain and aeolian (wind-transported) origin.

Woodman Point at the northern end of the Sound is comprised of Safety Bay Sand. This thins southward to a narrow strip along the current shoreline of the Jervoise Bay Northern Harbour. Tamala Limestone outcrops at the coast from Russell Road to Naval Base, then Safety Bay Sand reappears, and extends from the industrial strip to Cape Peron. The coastal fringe of the Safety Bay Sand is also known as the Becher Sand due to its marine rather than aeolian origins (Davidson, 1995). However for the purposes of this report, it will be referred to as the Safety Bay Sand.

3.2.2 Groundwater aquifers The Safety Bay Sand and Tamala Limestone extend down to approximately 25 m below AHD (Australian Height Datum, which is approximately equivalent to mean sea level). The Safety Bay Sand extends down to approximately 10 m below AHD, lying above and on the coastal side of the outcropping limestone. The Safety Bay Sand and the Tamala Limestone are often separated by a thin (0.5 to 1 m) silty or clayey shell bed (Appleyard, 1994).

Groundwater in the SBS and TL aquifers flows from the Jandakot Mound, located about 10 km to the east, and discharges into the nearshore marine environment. Groundwater flow through the TL aquifer is highly variable ranging from about 200 to 2000 m/year (Davidson, 1995), and is about an order of magnitude lower through the SBS aquifer (i.e. about 20 m/year). Near the coast, fresh groundwater overlies saline marine water that has moved into the lower section of the aquifer due to its greater density. As groundwater approaches the coast it is forced over this more

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 61 dense saline ‘wedge’, and follows the path of ‘least resistance’ to discharge into the shallow, nearshore zone.

The volume and distribution of groundwater flow is influenced by the hydraulic conductivity of the aquifer through which it is flowing, the presence of preferred pathways (‘karst’ formations or holes in the limestone) and fluctuations in sea level and groundwater elevation. The difference between groundwater elevation and sea level is particularly important in determining the rate of groundwater discharge. Passmore (1970) and Spencer (1993) found that the rate of groundwater discharge is inversely related to the sea level at the time.

It is anticipated that most groundwater discharge will occur in the nearshore zone. Investigations carried out by Thomas & Evans (1995) found that groundwater from the Tamala Limestone and the Safety Bay Sand discharged up to 40 m from shore in the vicinity of the Alcoa Refinery. Davidson (1995) mentions anecdotal reports of offshore groundwater discharge from springs connected to solution channels in the Tamala Limestone. Appleyard (1994) suggests that discharge from the Safety Bay Sand takes place at or near the shoreline, while discharge from the Tamala Limestone may take place several hundred metres offshore when it is overlain by the clayey confining bed. Where the limestone is not confined, groundwater discharge commonly takes place from springs and seeps at the base of limestone cliffs.

Groundwater also flows into the Sound from Garden Island. CSIRO research shows that there is no true unconfined aquifer at Garden Island: the local sand and limestone are so porous that rainwater rapidly filters down to sit on saltwater that is an extension of the two bounding water bodies, the Indian Ocean and Cockburn Sound. There are pressure differences between the two water bodies, with daily and seasonal variation in height and lateral movement. On the whole, the pressure differences result in eastward movement of groundwater, with diffusion from one side of the island to the other in a matter of months (Wykes et al., 1999).

3.2.3 Coastal flora and fauna

Eastern shore of Cockburn Sound There are two main vegetation complexes along the eastern coastal fringe of Cockburn Sound, as follows:

• Quindalup vegetation complex, which occurs on Safety Bay Sand. The two main areas are at Woodman Point Regional Park, and Mangles Bay/Cape Peron area (part of the Rockingham Lakes Regional Park). There are also isolated patches from James Point to Cape Peron, also at Woodman Point (Quindalup Dunes); and • Cottesloe Complex-Central-South (Spearwood Dunes), which occur on the coastal strip from Alcoa to the Jervoise Bay Southern Harbour, much of which is in the Beeliar Regional Park. The vegetated limestone cliffs in this area are unique in the Perth metropolitan region.

Vegetation associations within the Quindalup complex include herblands, sedgeland and Acacia shrubland. Vegetation associations within the Cottesloe Complex include low, closed heath dominated by Melaleuca leterita/Acacia saligna or Melaleuca huegelii; and dense low closed heath/thicket dominated by Dryandra sessilis.

62 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Searches of databases maintained by the Department of Conservation and Land Management (CALM) found the following threatened flora records for the coastal strip of the Sound:

• Grevillea olivacea (Priority 4 species), a low spreading to open shrub that occurs in coastal Quindalup dune and limestone areas. It is typically associated with Acacia shrublands on pale leached sands, and is considered likely to occur in suitable habitat from Woodman Point to Rockingham; • Dodonaea hackettiana (Priority 4 species) which occurs at Woodman Point (Halpern Glick Maunsell, 1997) and is also known from within Beeliar Regional Park (Keighery, 1996); and • Verticordia plumosa (Declared Rare Flora). Whilst there is a record for this species on CALM’s database for the Cockburn area, it is considered unlikely to still persist. The original collection for this record was in 1900 and there are no other populations of the species known from the locality.

Several other flora species of interest occur in the Cockburn Sound area (Keighery and Keighery, 1993; Halpern Glick Maunsell, 1997). These species are largely restricted to limestone and Quindalup substrates and include Rhagodia baccata subsp. dioica, Nemcia reticulata, Petrophile serruriae subsp. nov., Hibbertia spicata subsp. leptotheca and Pimealea calcicola. Survey work in the Quindalup dunes west of Coastal Reserve 24309 has also recorded a new variant of Stylidium bulbiferum which may represent a new species (A. Lowrie14, pers. com.; Halpern Glick Maunsell, 1998).

CALM databases were also searched for records of terrestrial fauna species of special conservation significance likely to occur in the area. Three species were found:

• Southern Brown Bandicoot Isoodon obesulus fusciventer. This species is locally common in dense swamps and other areas with intact understorey in the south-west of the state and has recently been downgraded from Schedule 1 to a Priority species. It is known from several populations in nearby areas including Woodman Point (How et al., 1996). CALM currently regards this species as ‘Conservation Dependent’. It is considered likely to occur throughout most of the area where the understorey remains intact; • Peregrine Falcon Falco peregrinus (a Schedule 4 species). The Peregrine Falcon is widespread across all of Australia, but only occurs at very low densities and with a patchy distribution. It is known to favour coastal areas and open woodlands amongst other habitats (Johnstone and Storr, 1998) and may be an occasional visitor to the area; and • Carpet Python Morethia spilota imbricata (a Schedule 4 species). This sub- species is broadly distributed across much of the south-west, but has been given its protected status due to the fact that it is not common anywhere in its range. Carpet Pythons are known to occur in Quindalup and Spearwood systems, particularly on the northern margins of the Perth Metropolitan area (Biota Environmental Sciences, 2000). The species is considered possible for the study area, but only likely to be at low abundance if present.

The Quindalup system generally supports a diverse reptile assemblage that is largely restricted to coastal dune systems. Several Quindalup species which were previously

14 Dr Alan Lowrie, Specialist consultant to the WA Herbarium.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 63 listed on the priority fauna listings, such as the Lined Burrowing Skink Lerista lineata and the Black-striped Snake Simoselaps calonotus, have recently been down- graded from this status.

Garden Island Although Garden Island is outside the CSMC boundary, the following information is included for completeness. The flora and fauna of Garden Island are of both regional and national significance.

The Quindalup vegetation complex on Garden Island includes sedgeland, heathland, shrubland, and extensive tracts of ‘low, closed coastal forest’ of Callitris preissii (Rottnest Island Cypress) and Melaleuca lanceolata. The latter is classified by CALM as a restricted and threatened community in Western Australia, with the Melaleuca lanceolata population being the only one in the Perth Metropolitan Region (disjunct from Margaret River). Several other disjunct populations of plant species that occur in this community are considered of regional significance, including Amyema melaleucae, Lasiopetaum angustifolium, Lepidium puberulum, Boronia alata, Myostis australis (may be a misidentification of Cynoglossum australe, another rarely collected species recently confirmed by an herbarium specimen – B. Wykes pers. com.), Leucopogon insularis and Pittosporum phylliraeoides (Keighery et al., 1997)

Fauna surveys have identified 94 species of birds, 14 species of reptile and one native mammal (the tammar wallaby) (Brooker et al., 1995, Robinson et al., 1987). The tammar wallaby Macropus eugenii (a Schedule 4 species ) and carpet python Morelia spilota occur abundantly on Garden Island, and bush birds of the island include disjunct populations of the Brush Bronzewing Phaps elegans (a Schedule 4 species) and Golden Whistler Pachycephala pectorali (Wykes et al., 1999). The island is a regionally important nesting site for many bird species. Garden Island is visited by 14 migratory species recognised under the Japan Australia Migratory Bird Agreement (JAMBA) and/or China Australia Migratory Bird Agreement (CAMBA), and is listed in the Register of the National Estate for a variety of natural and cultural heritage values.

3.2.4 Land uses Existing and planned land uses are shown in Figure 3.1, along with known or potential contaminated sites.

Urban areas The three local government authorities located within the Cockburn Sound catchment area are the City of Cockburn, the Town of Kwinana and the City of Rockingham. The two main urban areas are centred around Rockingham, Shoalwater, Safety Bay and Cooloongup; and Medina, Orelia, Calista, Kwinana and Parmelia. These are also the areas where urban expansion is planned, along with some areas of Wattleup and Beeliar around Thomson’s Lake. A population increase of 30% in the next 10 years is anticipated, and the new urban areas will require sewage and rubbish collection. This in turn will demand more capacity at rubbish tips and wastewater treatment plants to process urban wastes.

64 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE HOLDING PAGES (X2) FOR A3 FIGURE

Figure 3.1 Land uses in Cockburn Sound’s catchment

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 65 Second holding page for figure 3.1 (A3)

66 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Increased presence of Navy personnel at Garden Island is also expected. As part of the ‘Two Oceans’ defence policy, a 25% increase in personnel and ships (home- porting, maintenance, re-fitting) is planned by 2004. This will increase housing demand in mainland urban areas as well as expanding the naval presence on Garden Island.

Industry Heavy industry is centred on the suburbs of East Rockingham, Kwinana Beach and Naval Base, and includes an oil refinery, chemical production, an alumina refinery, power generation, a titanium dioxide plant, cement production and a nickel refinery. Heavy industry is of considerable importance to the State economy, with the Kwinana Industrial Area (KIA) alone estimated to produce goods worth at least $6 billion/year (Baker, pers. com.15). An international ship building precinct (construction, repair and maintenance of steel and aluminium-hulled vessels) is also based at Henderson, at the Jervoise Bay Northern Harbour. The attraction of these area for industry lies in the shipping facilities, road and rail transport, energy, cooling water, and proximity of synergistic industries.

The Fremantle-Rockingham Industrial Area Regional Strategy (FRIARS) report is intended to resolve potential conflict between industrial and other land uses in the region (WAPC, 2000a). FRIARS also recognises the KIA as the premier industrial area in the State, and seeks to protect the KIA and preserve opportunities for heavy industries and port facilities. The recommendations include the development of 800 hectares of general light industrial land over the existing townsite of Wattleup, and the extension of heavy industry into 100 hectares of land in the Hope Valley area. The proposed developments will ultimately see the loss of the towns of Wattleup and Hope Valley.

Other areas of industrial expansion include the marine construction and maintenance industry for the oil, gas and resource industry currently being built at the Jervoise Bay Southern Harbour, and the proposed East Rockingham Industrial Park (IP14) between Mandurah and Patterson Roads. The Jervoise Bay industries undertake a considerable amount of work maintaining and re-fitting Defence vessels, and are poised to undertake more with the current proposal to ‘home port’ 50% of all naval vessels at Garden Island.

Future proposals include the Global Olivine Water-to-Energy Plant, the Western Power upgrade, the James Point Private Port (which could include the live sheep trade) and the proposed FPA harbour.

Agriculture The main rural areas are in Mandogalup, Hope Valley Wattleup and Munster. Rural activities include:

• Market gardens (346 hectares); • Cut flower production (60 hectares); • Turf farms (38 hectares); and • Orchards (11 hectares).

15 Mike Baker, Executive Officer of the Kwinana Industries Council. Estimate currently being refined by the Kwinana Industries Council and the Chamber of Commerce and Industry

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 67 There is a general pattern of encroachment on these areas by urban and industrial use.

Conservation Coastal areas reserved for conservation include Woodman Point Regional Park, Beeliar Regional Park and Rockingham Lakes Regional Park. Regional Parks are managed under cooperative arrangements between State Government, Local government and the community, coordinated by CALM. The extent of these existing regional parks is unlikely to change. The ‘Bush Forever’ 10 year strategic plan (which combines the System 6 Update Program, Perth Environment Project, surveys by CALM and wetland mapping by the WRC) essentially adopts the existing Regional Park boundaries with little alteration (WAPC, 2000b). ‘Bush Forever’ is a ‘whole of government’ initiative, and implementation plan, designed to identify, protect and manage regionally significant bushland on the Swan Coastal Plain. ‘Bush Forever’ listings for coastal areas of Cockburn Sound are:

• Site No. 341, Woodman Point Regional Park (includes CALM managed land— Reserve 42469—reserved for the Conservation of Flora and Fauna); • Site No. 346, Henderson/Naval Base, Brownman Swamp, Mt Brown Lake and Adjacent Bushland (includes Metropolitan Region Scheme ‘A’ Class Reserve A24309, reserved for ‘Parks and Recreation’, and is part of Beeliar Regional Park; and • Site No. 355, Cape Peron and Adjacent Bushland, Peron,/Shoalwater Bay (includes a ‘C’ Class Crown Reserve, and is part of Rockingham Lakes Regional Park).

Garden Island is also listed as Bush Forever Site No. 63. It is also subject to additional protection under the Commonwealth Environment Protection and Biodiversity Act, is listed on the Register of the National Estate, and is a location for JAMBA/CAMBA species of migratory birds.

3.3 PRESSURES ON COCKBURN SOUND DUE TO LAND USE

3.3.1 Contaminants from different land uses

Urban areas In urban areas, gardening practices can contribute nutrients, metals and pesticides to groundwater, while a range of contaminants is present in urban stormwater runoff. Surface runoff from a large proportion of the Rockingham, Shoalwater, Safety Bay area is collected by the Lake Richmond drain, which discharges into Mangles Bay. This is the largest stormwater drain discharging into the Sound.

Urban areas also require sewage collection (or septic tanks) and rubbish collection, which in turn means increased capacity at rubbish tips and wastewater treatment plants is needed to process these wastes. Inappropriate storage and/or disposal of waste has the potential to contaminate land, groundwater and surface waters. For example, the old sludge drying beds of the Woodman Point wastewater treatment plant were one of the two main contributors to nutrient rich groundwater entering the Jervoise Bay Northern Harbour.

At the naval facility on Garden Island, there is wastewater treatment at a sewage farm close to the west coast of Garden Island, and effluent is disposed to surface

68 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE water/groundwater. The eastward movement of groundwater from one side of the island to the other in a matter of months (Wykes et al., 1999) has implications for sewage effluent currently discharged, and for any future contaminant plumes. Some stormwater runoff also goes directly into Careening Bay. There is also fuel storage on the island.

Industry Groundwater under industrial sites and tailing ponds can become contaminated with a range of nutrients and chemicals, depending on the industry in question. Contamination usually happens due to inappropriate storage of chemicals or inadequate maintenance of drainage/storage areas. Sometimes there are accidental spills on-site or in transit (road and rail).

Discharge of contaminated surface water from industries to the Sound is less common. Surface water at many of the industrial facilities is managed internally via sumps and soak wells. However, the old BHP concrete conduit has been observed to collect surface water from unused BHP land and drain into the Sound. There is also a stormwater drainage channel from the BHP sites that exits to Cockburn Sound immediately north of the BHP No. 1 jetty.

Agriculture Agricultural land use can contaminate groundwater with nutrients and metals (mainly cadmium) from fertilisers and wash down areas, pesticides and herbicides, and fuel from fuel storage areas. Losses of nutrients can be considerable due to the porous nature of local soils, and the amounts of nutrients and water needed to grow commercially viable crops.

Conservation Conservation uses are not considered to result in any contamination of surface or groundwater that might impact on Cockburn Sound.

3.3.2 Contamination of groundwater Contaminant loads to Cockburn Sound that occur via groundwater from the eastern shore have been estimated based on data provided by industry located within the catchment. This work updates that of Hine (1998, unpublished) and utilises the same methodology as Appleyard (1994) in estimating groundwater fluxes to the Sound.

This study focussed on the industrial strip that fringes Cockburn Sound and has not attempted to identify every source of groundwater impact throughout the catchment. Generic data for regional impacts on groundwater quality by various land uses was incorporated where appropriate. Groundwater monitoring data from 16 sites around the Sound (given in Appendix B) were reviewed to update contaminant discharges to the Sound. Most of the monitoring is for DEP or Water and Rivers Commission (WRC) license conditions, although the scope of groundwater monitoring and management programs at several facilities is well beyond licence requirements. In addition to these major industrial sites there are a large number of smaller industrial and commercial facilities that present potential impacts to the superficial aquifer and, in theory, the Sound. No attempt was made to quantify these impacts as the data are scarce and the magnitude of the potential impacts is very small compared to those of the larger facilities.

The available data were quite variable in quality, and data for all analytes of interest were not available for all sites. Nitrogen data were available for all the facilities

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 69 included in the survey and thus provide the most reliable indicator of contaminant loading trends. Estimates of total nitrogen inputs to Cockburn Sound from groundwater discharge are summarised in Table 3.1.

Table 3.1 Estimated loads of nitrogen in groundwater discharged to Cockburn Sound

SOURCE AQUIFER Tamala Limestone Safety Bay Sand (tonnes/year) (tonnes/year) Wesfarmers CSBP 53.83 20.24 Alcoa of Australia Refinery 0.00 0.00 BP Oil Refinery 1.48 3.42 WMC Resources 4.00 4.00 Water Corp (Woodman Point 38.78 * Western Power Corp 0.00 0.15 Nufarm Ltd 0.00 0.00 Nufarm Coogee 0.00 0.06 Tiwest Joint Venture 13.66 0.09 Coogee Chemicals 0.00 0.00 Western Bioproducts 27.01 * CBH ** ** Millenium Chemicals ** ** Spearwood Agricultural Area 45.63 * Subtotals 184.39 27.96 Total Groundwater 212.35 * Aquifer absent. ** No data available.

Nitrogen contributions to the Sound from groundwater are declining. Groundwater recovery at WMC’s Kwinana Nickel Refinery has reduced nitrogen discharges from approximately 500 tonnes/year to the current estimate of eight tonnes. There has also been a 14% improvement in ammonium discharges from the Wesfarmers CSBP site in the four years to 2000. Groundwater recovery adjacent to the Jervoise Bay Northern Harbour is also currently underway, and is expected to reduce nitrogen fluxes from the Woodman Point WWTP and the Western Bioproducts facility from the present 65.8 tonnes/year to 26.3 tonnes/year, a reduction of approximately 60%. With these reductions by industry, the relative role of rural areas is starting to become significant.

There is considerable groundwater contamination under industrial sites due to metals and organic compounds, the most well-publiced site being the area under the old CIK (Chemical Industries Kwinana) site (now Nufarm), which is contaminated by phenolic compounds. Risk assessments of this type of contamination have been carried out by Alcoa and Wesfarmers CSBP, and indications are that the mobility of such contaminants is limited. Other sites have not been subject to risk assessment.

No quantitative data are available for contaminant loads due to groundwater discharge from Garden Island, but groundwater investigations and monitoring bores show no contaminant sources from Defence facilities on the island other than nutrients from the wastewater treatment plant (Wykes et al., 1999), and this is currently being investigated (Wykes16, pers. com.).

3.3.3 Contaminant inputs due to surface waters and atmospheric fallout No information has been tabled on runoff from road reserves and urban catchments, or from atmospheric deposition. Hine (1998) estimated that nitrogen input to the Sound from surface runoff was 4.3 tonnes/year, and 20.4 tonnes/year from atmospheric deposition. There are some data for the Lake Richmond drain that

16 Dr Boyd Wykes, Environmental Officer, Defence Estate Organisation WA.

70 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE indicate stormwater runoff may be underestimated. Discharge from this drain to Mangles Bay was very variable from year to year between 1978 and 1986, but averaged 2,270 ML/year (DMH, 1992). Based on average concentrations of contaminants, the nitrogen loads discharged were 0.25 to 8.3 tonnes/year, and chromium, copper, lead and zinc loads were 50, 32, 98 and 104 kg/year respectively, which are of similar magnitude to some to industrial discharges (see Section 5.3.1).

South Jandakot Main Drain also discharges to the Sound, however monitoring data were not available at the time of this report. The location and extent of the urban drainage systems is not well documented and the location of discharge points is not readily available. As industrial discharges to the Sound reduce due to cleaner production practices and water reuse initiatives, the relative contribution from sources such as urban catchment runoff will attract more attention.

3.4 ENVIRONMENTAL MANAGEMENT OF LAND USE

3.4.1 Current management responses For the management of existing contaminated sites, new State legislation is proposed (as an amendment of Part V of the Environmental Protection Act) that will improve the identification, assessment and management of contaminated sites. The National Environmental Protection Council’s (NEPC) National Environmental Protection (Assessment of Site Contamination) Measure is also available to help industry adopt sound environmental practice as part of a normal business.

Many of the major contributors to groundwater contamination have already voluntarily undertaken groundwater remediation programmes (Kwinana Nickel Refinery, Wesfarmers CSBP). The Water Corporation has decommissioned its old sludge drying beds at Woodman Point. The Department of Commerce and Trade— as part of its commitments to gain approval for the Southern Harbour development —is undertaking remediation of groundwater contamination affecting the Jervoise Bay Northern Harbour. Alcoa has developed a Groundwater Management Plan to ensure that contaminants from its tailing ponds do not adversely affect Cockburn Sound. Rural groups are also looking at developing best management practice guideline for water and fertiliser use.

To prevent accidental spills, the Australian Dangerous Goods Code (Department of Transport and Communications, 1992) provides detailed, stringent guidelines for the transport of dangerous good, most of which are potential pollutants.

For new industries, license conditions developed during the EPA’s environmental assessment process will help minimise environmental impacts. The Water and Rivers Commission has also released draft guidelines for the location, specification and operation of underground storage tanks.

As noted in Section 2.5.1, the RAN has an EMP for Garden Island and HMAS STIRLING. The EMP is currently being revised, and will reflect and complement initiatives at the regional level. The Department of Defence is also currently investigating whether there are any localised impacts on seagrass on the east coast of the island due to groundwater contaminated by nutrients from its sewage farm (Wykes, pers. com). Garden Island is also protected under the Commonwealth Environment Protection and Biodiversity Act, and Defence, as a Commonwealth Department, is bound to manage the Island in accordance with the Act.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 71 At the local government level, kerbside recycling programs and composting and biodigestion to reduce organic waste to landfill are being adopted, along with the general philosophy of ‘waste management hierarchy’ (avoid, reduce, recycle, treat, dispose). Urban sensitive designs standards for new residential areas (to reduce stormwater pollution) continue to be implemented.

At the community group level, the Clean up Australia Day removes large amounts of rubbish.

3.4.2 Gaps in the management responses Groundwater quality below the larger industrial facilities that fringe Cockburn Sound is improving. There has been a dramatic decrease in licensed discharges since the 1970s, and further decreases are planned (see Section 5.3.1). Therefore, the relative contaminant contribution of the more diffuse sources throughout the catchment (e.g. rural areas) will increase. In most cases direct intervention of these sources will not be justified, but long-term improvement in groundwater quality throughout the catchment could be addressed by developing a catchment management plan. Such a plan would address the various land uses throughout the catchment, identify those activities that presently have the greatest impacts on groundwater quality, and develop approaches (e.g. best management practices) to minimise future impacts. The CSMC is the obvious organisation to prepare a catchment management plan and coordinate priority-based implementation of catchment management measures with local councils and major industrial and rural land users/owners. This process is already underway.

3.4.3 Gaps in information needed for management An inventory of contaminated sites in the catchment is needed. In addition, the following studies are recommended to improve understanding of contaminant inputs to the Sound from groundwater and surface water:

• Mapping of storm water catchments around the urbanised areas of Rockingham and Kwinana and the identification of discharges to the Sound. This should include the estimation of contributions to groundwater by the urban areas, location of major infiltration basins and the identification of storm water pipes that discharge directly to the Sound; and • A systematic approach to quantifying the quality of groundwater discharging to Cockburn Sound needs to be developed in cooperation with industries fringing the Sound. Good quality data are currently being collected at many sites, but the circulation of data is limited and there are likely to be inconsistencies in data interpretation. Key monitoring sites should be identified at each of the facilities where groundwater impacts are known to be occurring, with data being provided to a central data base on a quarterly or six monthly basis. Both the Safety Bay Sand and the Tamala Limestone aquifers should be monitored. In most cases, the data requirements would fall within the sites’ current monitoring programs, but a standard suite of analytes needs to be determined, including nutrients, metals and hydrocarbons.

72 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 4. SOCIAL AND CULTURAL COMPONENT

4.1 OVERVIEW Cockburn Sound is an extremely popular area for social uses, which include:

• Recreational fishing; • Water sports (swimming, boating, yachting, diving, windsurfing, skiing); and • Coastal use (beach activities, use of boat ramps).

Areas of social use are shown in Figure 4.1.

In addition, Cockburn Sound is important for aesthetics and heritage, which are not so much social uses as values that are held. Each is discussed in turn below.

4.2 SOCIAL AND CULTURAL USES OF COCKBURN SOUND AND ITS FORESHORE

4.2.1 Existing and potential social uses

Recreational fishing Data on boat-based recreational catch and fishing effort for Cockburn Sound were recently collected by a 12-month survey of coastal waters from Augusta to Kalbarri during 1996/97 (Sumner and Williamson, 1999). The study area was divided into 5 x 5 nautical mile blocks which were used to record catch and fishing effort. Block 58BQ is centred on Cockburn Sound, Block 57BQ includes the southern fringe of Cockburn Sound plus Shoalwater Bay and part of Warnbro Sound, and Block 59BQ includes the northern fringe of Cockburn Sound and most of Owen Anchorage. During the survey, fishers returning from their fishing trip were interviewed at boat ramps and shown a map of the area and asked to identify the block where they fished. Block 58BQ was recorded for most fishing within Cockburn Sound. Data for Cockburn Sound are summarised in Table 4.1, along with data for Owen Anchorage (Block 59BQ) for comparative purposes.

Table 4.1 Recreational fishing effort in the Cockburn Sound/Owen Anchorage region, 1996/97

FISHERY BLOCK AND NO. BOAT TRIPS NO. BOAT TRIPS TOTAL NO. OF LOCATION ANGLING CRABBING* BOAT TRIPS Block 58BQ: centred on Cockburn 9,372 2,711 12,083 Sound Block 59BQ: centred on Owen 3,305 826 4,131 Anchorage * mainly crabbing, but some of these boat crews were also angling.

Cockburn Sound is a very popular area for recreational fishers. Within coastal waters from Augusta to Kalbarri it is second in importance only to the Hillarys area (Block 62BQ where the number of boats fishing in a 12-month period exceeded 15,000).

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 73 HOLDING PAGES (X2) FOR A3 FIGURE

Figure 4.1 Social and cultural uses of Cockburn Sound

74 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Second holding page for figure 4.1 (A3)

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 75 The main fish species caught in Cockburn Sound and Owen Anchorage by boat- based recreational fishers are: Australian herring (13 tonnes), squid (58,000 animals, weight not known), King George whiting (9 tonnes), whiting other than King George (7 tonnes), skipjack trevally(5 tonnes), tailor (3 tonnes) and garfish (2 tonnes) (Sumner pers. com.). By comparison the commercial finfish catch (excluding baitfish) reported for 1998 (commercial fisheries block 9600) comprised mainly garfish (22 tonnes), Australian herring (21 tonnes), tailor, skipjack trevally, King George whiting, yellowtail scad and pink snapper (Penn, 1998). The total commercial catch of fish (excluding baitfish) was 60 tonnes, compared to the recreational catch of 39 tonnes for the fish listed above (excluding squid). Thus, there is considerable overlap between the fish species caught by commercial and recreational fishers. Furthermore, the fish catch by boat-based recreational fishers is of similar size to that of commercial fishers. An earlier study (DCE, 1979) estimated the boat-based recreational fish catch in 1978 as 210 tonnes. However, the two studies are not directly comparable due to the different methods used. Among other differences, the 1978 study included fish and crabs caught outside the Sound and landed at a boat ramp inside the Sound. The 1996/97 survey only included fish caught within Cockburn Sound.

Cockburn Sound is also particularly popular with recreational crabbers, who caught 18.8 tonnes in 1996/97. The boat-based recreational catch was 5.4% of the commercial catch for the same period (347 tonnes; Penn, 1999). The boat-based recreational catch in 1978 was estimated as 120 tonnes compared to a commercial catch 26.7 tonnes for the same period (DCE, 1979). The comparative sizes of the recreational and commercial catches appear to have changed since the 1978. However, the results are not directly comparable for the reasons given above, although the trend of a declining recreational catch and expanding commercial catch is probably realistic.

Recreational boat-based fishing effort is fairly widespread throughout the Sound, although fishing for pink snapper tends to occur near the channel markers south of Parmelia Bank, including Woodman Channel, Three Fathom Bank and the main FPA entrance channel. Recreational crabbers tend to fish in shallower waters than their commercial counterparts. Net fishing is permitted in the Sound, but there is a Department of Defence ban on recreational netting all year round within naval waters around Garden Island (see Figure 4.1).

Based on predicted population increases (DOT, 1999), recreational fishing pressure will increase by about 30% in the next 10 years, and by more than 50% in the next 20 years.

Water sports Swimming appears to be the most popular water sport in Cockburn Sound, based on a 1978 survey of beach use carried out during the 1976–79 Cockburn Sound Environmental Study (Feilman & Associates, 1978), and again in a 1994 survey (Dielesen, 1994). Kwinana, Wells Park, Rockingham and Palm Beaches and Woodman Point are popular for swimming, and Challenger Beach, Kwinana Beach and Woodman Point are popular for shore-based fishing. Sailing (yachting and windsurfing) is popular in Mangles Bay. The area immediately offshore from Churchill Park, Rockingham, contains a number of small wrecks (boats and an aeroplane), and is an regionally important SCUBA diving site as well as being used extensively for diver training by dive clubs in the Perth metropolitan region (mainly the southern suburbs).

76 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE About two-thirds of Garden Island is open to the public in daylight hours, and is also popular for picnics, swimming, diving (snorkel and SCUBA), fishing, sailing (yachting and windsurfing) and surfing. There is a Department of Defence ban on carrying and use of spear-guns and gidgees on Garden Island and within Naval Waters around Garden Island. The Department of Defence also bans the landing of pets on the island from boats, and no open fires are permitted at any time of the year (free gas barbecues are provided at two public picnic areas maintained jointly by CALM and Defence). For safety and security reasons, access to the south-eastern and northern sectors is restricted, and private boats are advised to avoid waters adjacent to naval facilities. Access to Garden Island is only by private boat, and visitors must leave before nightfall.

There is also an Industrial Exclusion Zone between Kwinana and Challenger Beaches (Figure 4.1). Many of the industries in this area operate under State Agreement Acts that extend to the water mark, and so the land is effectively private property. Strictly speaking, use of the beaches in this area requires the permission of the industries occupying the adjacent land, but there is regular informal17 use of the Barter Road Beach (north of the BHP No.1 Jetty) mainly for horse swimming.

Water skiing and ‘free style’ driving of personal water craft (i.e. jet ski) are restricted to areas in Mangles Bay/Palm Beach. There is also a Department of Defence ban on personal water craft all year round within naval waters around Garden Island. Outside these areas, personal water craft are permitted but for the purposes of boating regulations are considered as power boats, and must be driven accordingly.

There are no recent surveys of beach use in Cockburn Sound, but a snapshot survey of Owen Anchorage in 1998 by Annandale (1999) included Woodman Point, and found a similar pattern of use to the 1978 and 1994 surveys mentioned above (Figure 4.2).

Annandale (1999) also investigated the issue of potential conflict between users, and found that in most cases potential conflict was in the summer months when there were more people using the study area. Swimmers were affected by the greatest range of other users, with people using boats and/or jet skis cited most by other users as affecting, or interfering with their recreational use of the area. Fishers were the next most likely to affect other users of the area. Users in conflict with other users were often engaged in the same activity, e.g. pleasure boats versus other pleasure boats, and fishers versus other fishers.

Coastal Use Coastal use includes activities such as boat launching, picnics, visits associated with swimming, exercising, relaxation and exercising dogs. Horse exercising between the Kwinana Grain Jetty and the Kwinana Wreck, and between the BHP No. 1 Jetty and Western Power’s cooling water outlets (Barter Road Beach). At the Kwinana site horse exercising is restricted to the hours of 4:00 am to 8:00 am, to avoid conflict with swimmers and beach users. There are no time restrictions for horse exercising at Barter Road Beach.

17 There has been no formalisation of ‘no go’ areas along the beach between BHP No.1 Jetty and Western Power’s cooling water outfall by the Kwinana Town Council.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 77 Bathers 200 Boats Cars in Car Park Fishers 150 Pic nic ker s SCUBA Divers

100 Number of users of Number 50

0 Woodman Coogee Beach Northern End Robbs Jetty South Beach Fremantle Point of Coogee (Success Mar inas Beach Harbour to Catherine Point)

Figure 4.2 Peak recreational use in Owen Anchorage during snap-shot survey Note: From Annandale (1999), reproduced courtesy of Cockburn.

Cockburn Sound is particularly popular for family/small boat use due to its sheltered nature. An indication of the intensity of recreational boat use can be obtained from a 1999 Department of Transport survey of public boat ramp. Estimated boat use at all the public ramps in from Owen Anchorage to Warnbro Sound is shown in Table 4.2, along with the estimated level of use in 2011 and 2021 based on predicted population growth and assuming a similar level of boat ownership. The estimated 44,270 boats launched in Cockburn Sound in Table 4.2 is considerably larger than the estimated of angling/crabbing boat trips in Table 4.1 (12,083 boat trips), presumably as the former includes all craft (power boats, yachts, windsurfers, personal water craft) and— unlike Table 4.1—incorporates statistics for boats that go outside Cockburn Sound (especially prevalent at the Cape Peron launching ramp).

The busiest times are September to April, especially January/February. The numbers in Table 4.2 may also underestimate peak use. For example, at peak times at the Cockburn Power Boat Association, about 1500 boats/day use the public ramp and 500 boat s/day at CPBA use the private RAMP (John Smedley18, pers. com.).

Coastal access to the coast between the CBH jetty and Woodman Point is becoming increasingly restricted due to industrial development. Over this approximately 14 km stretch of coastline the only recreational access point that is formally recognised is several hundred metres along Challenger Beach, part of which has recently been covered by rock fill used in road/shoreline stabilisation works undertaken by the Kwinana Town Council. As noted earlier, there is regular, informal use of the Barter Road Beach, although this will diminish if current development proposals are approved (the James Point Pty Ltd private port and James Point Pty Ltd livestock holding facility). Community concerns have been expressed that more and more people are wanting beach access, while less and less beach is becoming available. Judging by the data in Table 4.2, the lack of access to this area of coastline will also lead to increased congestion in other areas: there is the

18 John Smedley, Cockburn Power Boat Association

78 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE potential for intense recreational pressure at the Woodman Point and the Rockingham foreshore. Existing facilities, particularly the boat ramps, also need upgrading. Recreational plans that have been suggested to alleviate this pressure include the Mangles Bay marina, and the Wanliss Street jetty development.

Table 4.2 Estimated boat use at public boat ramps

BOAT RAMP ESTIMATED NUMBER OF BOATS USED PER YEAR (POWER BOATS AND YACHTS) 1999 2011 2021 Owen Anchorage No ramps000 SUBTOTAL000 Cockburn Sound Woodman Point 16,520 21,375 24,673 Challenger Beach, Naval Base 1,980 2,601 3,030 Kwinana Beach (Wells Park), 3,300 6,406 8,622 Kwinana Palm Beach, Rockingham 9,250 12,600 15,162 Cape Peron, Rockingham 13,220 20,298 25,964 SUBTOTAL 44,270 63,280 77,451 Warnbro Sound Carlisle St, Safety Bay 1,980 3,004 3,899 Bent St, Safety Bay 6,610 9,872 12,895 Donald Drive, Safety Bay 2,640 3,981 5,176 SUBTOTAL 11,230 16,857 21,970 TOTAL of 8 ramps 55,500 80,137 99,421 Note: does not include the private boat ramps of Success Harbour or the Cockburn Sound Powerboat Association.

4.2.2 Aesthetics/seascapes The Café strip and public walkways at Palm Beach are very popular with locals and tourists, especially in January/February. Enjoyment of passive recreation in these areas (e.g. sitting in a Café and admiring the view) depends greatly on the scenic value of the coastal features, the clarity of the water and ambience of the area.

Aesthetic enjoyment of the rest of Cockburn Sound, whether boat or shore based, depends on a variety of values, including the scenic value of the seascape, good water quality, ‘closeness to nature’, ease of access, the diversity of marine life in protected/sheltered waters and availability of clean seafood to catch/collect.

4.2.3 Heritage

Maritime heritage Cockburn Sound has a long association with early settlement in Western Australia. Captain James Stirling established the first free settlement in Australia at Cliff Head on Garden Island in 1829, although the settlement moved to the mainland some months later.

The exposed conditions in Gage Roads led increasing use of sheltered anchorage in Cockburn Sound. Careening Bay was a popular ship repair and cargo unloading area in the 1800s. However, Cockburn Sound was eventually marginalised after 1900 by the construction of Fremantle port.

There are four historic wreck sites in Cockburn Sound: the Day Dawn (1890) and Dato (1893) in Careening Bay, and the Contest (1874), and Amur (1887) in Mangles Bay (Kenderdine, 1995). The Day Dawn and Dato also have national heritage listing in the Register of the National Estate.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 79 Indigenous heritage According to the National Native Title Tribunal, Cockburn Sound is located within a region covered by two registered Native Title claims: WC99/6—Combined Metropolitan Working Group, and WC98/58—Gnaarla Karla Booja. The area is, however, subject to another claim, WC95/86—Ballaruk, which has failed the registration test and has been referred to the Federal Court. The current status of these claims is uncertain and this may have implications under recent amendments to the Native Title Act (effective from 30 September 1998) which are difficult to define at this stage. Despite this, the Combined Metropolitan Working Group and Gnaarla Karla Booja claims are still valid under the old Native Title Act.

There are many archaeological and ethnographic sites close to water sources in the Perth metropolitan area, but very little archaeological evidence for use of the coastal fringe. It is known that large groups of Aboriginal people congregated on the coast and estuaries during summer and autumn, when fish and other aquatic resources were abundant. The lack of archaeological evidence for occupation and use of the Cockburn Sound coast may be partly due to the intensive development that has taken place. Also, much of the Cockburn Sound catchment area has never been systematically surveyed for Aboriginal sites. As Aboriginal burial sites are commonly found in coastal dunes all along the West Australian coast, it is possible that the coastal dues of Cockburn Sound may contain buried skeletal material, or subsurface archaeological material.

The State Register of Aboriginal Sites records Site S02169, designated as the ‘Indian Ocean’, which corresponds to the area of water between the mainland and Rottnest, Carnac and Garden Islands and Cockburn Sound. The site concerns Aboriginal mythology about the creation of the islands, especially Rottnest, during the sea level rise that took place about 10,000 years ago (see Section 2.1). There are two versions of the myth on the site file, but access to this information requires the permission of the relevant Aboriginal groups.

4.3 PRESSURES ON COCKBURN SOUND DUE TO SOCIAL AND CULTURAL USES

4.3.1 Existing and potential uses Recreational fishing can cause environmental pressure due to overfishing; damage to the seabed from fishing gear, moorings, anchors and landings; discharge of sullage; oil spills; and litter (lost fishing gear and rubbish).

The types of fishing gear that recreational fishers are allowed to use is restricted, and damage to the seabed is minimal: most recreational fishing is static.

There is little information on changes in recreational pressure in the Sound. Recreational use has certainly increased, but fishers are more environmentally aware. The recreational fishing survey by Sumner and Williamson (1999) found that most fishers were aware of the fish size limits and bag limits set by Fisheries WA., and kept to them.

Over-exploitation of some species (integrated with commercial take) may be a concern with increasing recreational use due to population growth.

80 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Water sports As for fishers, non-fishing boat use can cause damage to the seabed from moorings, anchors and landings; discharge of sullage; oil spills; and litter. Powerboats and personal water craft can also scour the seabed (including seagrass meadows) with their propellers. Some noisier forms of boat use (jet skis) may also disturb wildlife.

It was estimated that 1.8 hectares of seagrass was lost due to some 250 boat moorings in Mangles Bay in 1987 (Lukatelich et al., 1987). A typical mooring can remove between 3 to 300 square metres of seagrass, depending on the type of mooring and length of mooring chain. It is noted that non-invasive types of moorings are now available.

Coastal use The main environmental pressure due to coastal uses is erosion and loss of foreshore, and degradation of coastal vegetation. Dog and horse faeces and rubbish can also affect water quality.

The increased pressure likely on coastal areas—due to both increased population pressure and decreasing availability of coast—has already been noted.

4.3.2 Aesthetics/seascapes No pressure is expected on the Sound due to passive recreation.

4.3.3 Heritage No pressure is expected on the Sound due to either maritime or aboriginal heritage values.

4.4 ENVIRONMENTAL MANAGEMENT OF SOCIAL AND CULTURAL USES

4.4.1 Current management responses

Marine conservation The Marine Parks and Reserves Selection Working Group has recommended that the representativeness of the existing Shoalwater Islands Marine Park would be enhanced by extending its boundaries to include the area west of Garden and Carnac Islands out to Five Fathom Bank (CALM, 1994). Bulletin 907 (EPA, 1998) notes that the Minister for the Environment has requested the Marine Parks and Reserves Authority to consider including seagrass meadows on eastern Garden Island, Southern Flats and Mangles Bay in the State-wide System of Marine Conservation Reserves. No further action has been undertaken on this proposal.

Maritime heritage Under the Maritime Archaeology Act of 1973, all wrecks or objects dating prior to 1900 are deemed to be `historic shipwrecks or relics’ within the meaning, and subject to the provisions, of the Act. The requirements of the Act are that the finding of any object subject to the provisions of the Act be notified to the Western Australian Maritime Museum and that in the case of any discovery being made of a number of objects, or a wreck site, all activity be halted until an investigation to assess the importance of the site has been carried out.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 81 Indigenous Heritage Under the Federal Act, Aboriginal Groups who have passed the registration test retain the right to negotiate over certain developments that impinge on their claimed native title rights and interests.

Under the State Aboriginal Heritage Act 1972, all Aboriginal people who wish to be consulted about a proposed development should be included in the surveys and have their concerns reported. It is also an offence under the Act to disturb any Aboriginal site (e.g. burial grounds, symbols, objects, paintings, stone structures, carved trees).

Recreational fishing Recreational fishing is currently managed by means of licences, bag limits, minimum sizes (e.g. fish length, crab carapace width) and gear controls set by Fisheries WA and enforced by Fisheries Officers. Recreational crabbers may use hand, non- piercing wire hook, wire scoop net and drop net. Recently, there have also been seasonal closures for pink snapper.

A review of recreational fisheries management arrangements for the west coast is currently under way (Fisheries Management Paper No. 139). Amongst a variety of management measures, the Paper revisits minimum sizes for various fish species according to their size when sexually mature, and sets bag limits for most species according to how ‘prized’ or vulnerable they are. Implementation of this Management Plan will help ensure sustainable recreational fishing in the waters of Cockburn Sound.

Fisheries WA also make a variety of educational brochures aimed at promoting environmentally responsible fishing.

Community groups such as the CPBA and Recfishwest play an active role in encouraging environmentally responsible fishing. For instances, the CPBA promotes single species fishing competitions, where only one fish can be weighed in for each species.

Water sports and coastal uses Local governments play a key role in the management of water sports and coastal areas by zoning to separate incompatible uses, ensuring suitable facilities (rubbish bins, toilets) are available and providing suitable paths and/or barriers to control erosion. There are a number of coastal, foreshore and/or recreation management plans in place: City of Cockburn has a Coastal Management Strategy, the Town of Kwinana has a Coastal Management Plan (currently being updated), and the City of Rockingham has a Strategic Coastal Management Plan (currently under review). It is anticipated that these will be revised (if necessary) to ensure consistency with the CSMC’s EMP (refer also to Section 2.5.1).

Mooring owners in a small mooring area at the north of Garden Island have been required by the Department of Defence to install non-invasive moorings where damage was occurring to seagrass. The Department of Defence has also placed a ban on further placement of moorings.

4.4.2 Gaps in the management responses A key gap in management responses is a coordinated mechanism for dealing with pressures on recreational access to Cockburn Sound. The eastern foreshore of Cockburn Sound from Cape Peron to Woodman Point is 25.4 km long, but only

82 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE about 14.3 km is freely accessible to the public due to the presence of the Jervoise Bay industrial area (3.8 km) and the main Kwinana Industrial Area from Alcoa to Wesfarmers CSBP (7.3 km). There are additional small areas of beach within the Kwinana Industrial area that are accessible to the community and presently used informally. As noted previously, recreational access to the eastern shoreline of Cockburn Sound is decreasing due to ongoing industrial development, yet recreational pressure in the region is increasing. At present, there is no coordinated management approach examining ways in which the existing coastline—and associated recreational facilities—can be developed/upgraded/re-zoned to best meet present and future recreational needs. Any management and planning undertaken will need to encompass a broader area than Cockburn Sound, as boat launching facilities in the Sound are also used to access adjacent waters. Improved recreational access and facilities in areas adjacent to Cockburn Sound could help reduce recreational pressure on the Sound. A management matter related to coastal access is the potential effect of coastal structures on adjacent beaches. The Coastal and Facilities Management Branch of the Maritime Division of the Department of Transport have a system for providing preliminary coastal engineering advice on coastal structures. There is, however, no standard approach presently available for detailed assessment of coastal erosion measures and adapting them for local conditions in Cockburn Sound. This is in large part due to the lack of understanding of coastal processes in Cockburn Sound (see also Section 2.5).

4.4.3 Gaps in information needed for management Consideration of the social and cultural uses of Cockburn Sound is arguably one of the most sensitive management issues in Cockburn Sound, yet the social and cultural pressures on Cockburn Sound have been studied far less than commercial and industrial pressures and environmental impacts. Clearly, this area needs further study. In particular, data is needed on the recreational uses of the Cockburn Sound area. A comprehensive survey that establishes types of use, areas of use and intensity of use is urgently needed for environmental management and planning. Ideally, this survey could also examine the ways in which Cockburn Sound is valued, the key attributes that underpin how it is valued, and what needs to be improved. Fishing is one of the most important recreational uses of Cockburn Sound, and more data is needed on recreational fishing effort, both boat-based and shore-based. It is noted that a Fisheries WA survey of recreational fishing in Cockburn Sound—boat- based and shore-based (funded by the Fisheries Research Development Council)— will commence on 1st September 2001 (Neil Sumner, pers. com.). Better estimates of recreational catches will be needed for integrated catch management of fisheries, and to plan for increased recreational fishing pressure as the population increases. There is an encouraging precedent here, with the voluntary resource sharing agreement recently agreed to by the fishing industry and recreational fishers for crabs in Cockburn Sound. To ensure sustainable fishing, more information is needed on the biology of commercially and recreationally important fish species. Management measures will be different depending on whether species are resident in the Sound, or have important links with adjacent waters such as the Swan River. For instance, it is known that the Sound is an important nursery for snapper, that the Swan River an important nursery for Sound’s whiting population, and that crabs can complete their entire life cycle in the Sound (Penn, 1977).

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 83

5. ECONOMIC COMPONENT

5.1 OVERVIEW Economic uses of Cockburn Sound include:

• Industry; • Shipping (Commercial and Defence); • Commercial fishing; • Aquaculture; and • Tourism.

Industrial areas, shipping routes, and aquaculture lease areas are shown in Figure 5.1. Industrial uses that affect the catchment of the Sound were addressed in Section 3, so only direct impacts on the Sound are considered in this section.

5.2 ECONOMIC USES OF COCKBURN SOUND

5.2.1 Industry Existing and proposed industrial uses in Cockburn Sound were discussed previously in Section 3.2.4. As noted in Section 3.2.4, the Kwinana Industrial Area alone produces goods worth at least $6 billion/year.

5.2.2 Shipping (Commercial and Defence) Cockburn Sound is the outer harbour of the Port of Fremantle, and the navigation channel dredged through Parmelia and Success Banks is the only means of access to Cockburn Sound for larger cargo and naval vessels. Monthly and annual ship arrivals recorded by the FPA for Cockburn Sound in 2000 are shown in Table 5.1.

Table 5.1 Ship arrivals to Cockburn Sound (FPA outer harbour) in 2000

PERIOD COMMERCIAL FISHING NON- NAVAL TOTAL VESSELS VESSELS COMMERCIAL VESSELS* SHIPPING VESSELS January 2000 57 0 1 6 64 February 2000 71 0 2 15 88 March 2000 66 0 1 19 86 April 2000 64 0 3 21 88 May 2000 57 0 3 26 86 June 2000 57 0 0 14 71 July 2000 54 0 5 18 77 August 2000 53 1 5 17 76 September 2000 55 0 0 9 64 October 2000 58 0 2 21 81 November 2000 49 1 0 32 82 December 2000 69 0 1 34 104 TOTAL 710 2 23 232 967 Disclaimer: Whilst every effort has been made to ensure that the above information is accurate, the Fremantle Port Authority gives no warranty regarding this information and accepts no liability for any inconvenience, or any direct or consequential loss, arising from reliance upon this information. Readers should undertake their own inquiries to any of the facts referred to before acting upon them. * Information from Lieutenant Commander Robert Walker, Port Manager of HMAS Stirling

The total number of vessels visiting the outer harbour in 2000 was about 50% of the total for the inner and outer harbour (1,945 arrivals).

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 85 HOLDING PAGES (X2) FOR A3 FIGURE

Figure 5.1 Economic uses of Cockburn Sound

86 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Second holding page for figure 5.1 (A3)

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 87 There are six commercial jetties in Cockburn Sound (one of which is out of service). Information on the jetty operators and types of cargo handled is given in Table 5.2.

Table 5.2 Operators and cargo handled at commercial jetties in Cockburn Sound

JETTY OPERATOR CARGO HANDLED Alumina Refinery Jetty Alcoa of Australia Ltd Loading of alumina loaded (north side of jetty) Unloading of bulk caustic soda unloaded (south side of jetty) Steelworks Jetty No. 1 BHP Transport Out of service Steelworks Jetty No. 2 BHP Transport Loading and unloading of cement clinker, mineral sands, silica sands, iron ore, copper concentrates, gypsum slag, sugar, fertiliser, petroleum coke, LPG, coal, limestone, dolomite, manganese Oil Refinery Jetty BP Refinery *Kwinana) Loading and unloading of bulk petroleum Pty Ltd products Bulk Cargo Jetty Berths 1 & 2 Fremantle Port Berth 1: Unloading of phosphate, phosphoric Authority acid, sulphur, ammonium sulphate, potash, ammonia, urea Berth 2: Unloading of refined petroleum, fertilisers, caustic soda, phosphates, ammonium sulphate, sulphuric acid, LPG Kwinana Grain Jetty Cooperative Bulk Loading of grain Handling Ltd

In the 1999/2000 year, the FPA (Inner Harbour and Outer Harbour) handled 23.4 million tonnes of commodities. Actual tonnages handled by individual jetties in Cockburn Sound is commercially confident information, but a breakdown of the commodities handled in the Inner Harbour and Outer Harbour is shown in Figure 5.2.

FPA Imports/Exports 1999/2000

Live sheep 1% Other 18% Chemicals 1%

Cement clinker 1% Petroleum products Mineral sands 1% 35%

Silica sands 1%

Animal feeds 2%

Caustic soda 2%

Fertilisers 3% Alumina 11%

Grain 24%

Figure 5.2 Types of commodities handled by the FPA Based on available data, it will be 20 years before overflow in the Inner Harbour is breached, and a facility is needed in Cockburn Sound. A variety of alternative designs (offshore ports, private ports, floating breakwaters) are presently being considered by the FPA.

In addition to the ship movements recorded by the FPA, Jervoise Bay supports six major shipbuilding enterprises which use the study area to sea trial their vessels. Sea trialing is undertaken to ensure that the boats are seaworthy, predominantly in Cockburn Sound but sometimes further north along the FPA channel and into Owen Anchorage.

88 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 5.2.3 Commercial fishing Cockburn Sound has been a site for commercial fishing for many years, but was not registered as such until 1977. The ‘Cockburn Sound Fisheries Block 9600’ defined at that time is all waters within a line that extends from South Mole at Fremantle west to Stragglers Rocks, then through West Success Bank to Carnac Island to Garden Island, along the eastern shore of Garden Island and to John Point on the mainland. Although this region includes Owen Anchorage and Cockburn Sound, most commercial fishing occurs within Cockburn Sound.

There are four commercial fisheries that operate within Fisheries Block 9600, and a further two commercial fisheries that operate partly within Cockburn Sound. Details of these six fisheries are summarised in Table 5.3, and are largely based on data from the 1999/2000 State of the Fisheries Report (Penn, 2000).

Table 5.3 Details of commercial fisheries operating in Cockburn Sound Fisheries Block 9600

FISHERY AND BOUNDARIES TARGET SPECIES NO. OF 1999/2000 1999/2000 LICENCES CATCH VALUE* Cockburn Sound (Crab) Managed blue manna (blue 16 323 tonnes ~$1,000,000 Fishery: swimmer) crab Cockburn Sound Fisheries Block 9600#1 Cockburn Sound (Fish Net) garfish and Australian 4 Managed Fishery: herring (lesser amounts Cockburn Sound Fisheries Block of shark, whiting and #2 9600 mullet) 96.5 tonnes ~$240,000 Cockburn Sound (Line and Pot) whiting, pink snapper, 32 Managed Fishery: Australian herring (not all Cockburn Sound Fisheries Block shark, garfish, squid, currently 9600 octopus, utilised) Cockburn Sound (Mussel) Managed Mussels. Wild fishery 14 state- 683 tonnes ~$1,800,000 Fishery: now very small, and wide, 3 in (state-wide) (state-wide) Cockburn Sound Fisheries Block licences transferred to Cockburn 9600 aquaculture licences Sound The West Coast Beach Bait (Fish Whitebait. 13 107 tonnes ~$200,00 Net) Managed Fishery: (total Moore River to Tims Thicket#3 fishery) (south of Mandurah) West Coast (Purse Seine) Managed Pilchards, some scaly 14 1,103 ~$700,000 Fisheries: mackerel. tonnes Lancelin to Cape Bouvard, (total excluding Marmion Marine Park fishery) * To fishers. #1 Excluding naval waters between Colpoy Point and Collie Head (at south end of Garden Island. #2 Excluding an 800 m wide strip along 800 m length of Kwinana Beach, and an 800 m wide strip from Flinders Lane to John Point(the tip of Cape Peron), and navy waters between Colpoy Point and Collie Head. #3 Excluding an 800 m wide strip along 800 m length of Kwinana Beach, and an 800 m wide strip from Flinders Lane to John Point.

The blue manna crab fishery is the most valuable in dollar terms, and Cockburn Sound has long been a productive area for this species. Due to increasing levels of competition between commercial and recreational fishers, a voluntary resource sharing agreement was recently agreed to by the fishing industry, Recfishwest, and Fisheries WA (Fisheries WA, 2000). The agreement will reduce the number of pots used by professional fishers from 1,600 to 800 over three years, or will achieve a share of the catch of five-eighths commercial and three-eighths recreational.

Finfish catches obtained by the Cockburn Sound (Fish Net) Managed Fishery have been increasing since the 1970s, causing some concern. Conversely, the Cockburn Sound (Line and Pot) Managed Fishery’s catches of King George whiting, squid and octopus have all declined in recent years. Reasons for the declines are not fully understood, but are thought to include environmental factors, fishing pressure and/or

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 89 market considerations. Finfish catches from these two fisheries have a relatively small dollar value, but proximity makes the catch an important contribution to the Perth metropolitan market for fresh table fish.

Harvesting of wild mussels (Mytilus edulis) began in Cockburn Sound in the early 1980s, but catches have since declined and have been very low or nonexistent in recent years.

5.2.4 Aquaculture Mussel aquaculture in Western Australia began in Cockburn Sound in 1988 to overcome the declining catches of the wild capture fishery and to provide a more consistent source of product. Mussel aquaculture is undertaken in Cockburn Sound, Warnbro Sound and Albany, and for reasons of commercial confidentiality the harvests for the Cockburn Sound area cannot be released. However, a significant proportion of the 680 tonne/year harvest comes from Cockburn Sound (Western Fisheries, 2001), and so the dollar value this industry is of the same order as the crab fishery.

There are three lease areas in Cockburn Sound: north Garden Island, Kwinana Grain jetty, and recently (1999) Southern Flats. The Kwinana Grain jetty used to be the main site, but the long-term tenure of this area was uncertain, which led to the move to Southern Flats. The first harvest from the Southern Flats area has returned better growth rates than expected (Western Fisheries, 2001). The north Garden Island has only a small area (approx. 20 ha) in use (Glen Dibben19, pers. com).

The industry requires relatively deep water (>10 m), good circulation, excellent water quality (i.e. it requires low levels of faecal bacteria, contaminants, and toxic species of phytoplankton), and slightly nutrient-enriched conditions (so that there is sufficient phytoplankton for the mussels to feed on). To achieve reasonable growth rates for mussels, chlorophyll levels need to be consistently above 1 µg/L, although for best results the mean annual concentration should exceed 2 µg/L (Saxby, cited Pearce et al., 2000).

Navigation is a major issue constraining further aquaculture development in Cockburn Sound, although small recreational boats are able to move in among the aquaculture lines and fish if they want to.

5.2.5 Tourism Most boat tourist operators pass through Cockburn Sound to the more scenic islands and reefs of the Shoalwater Islands Marine Park.

A survey of 17 tourism operators (about 60–80% of tour operators using the Cockburn Sound/Owen Anchorage area) indicated that tourist activities included marine charters (involved in diving, deep-sea fishing, sailing, seal and dolphin watching and sight seeing), divers, dolphin tours, and a caravan park and recreation camp at Woodman Point (Annandale, 1999). Most tourist activities were run predominantly in the summer months from September/October to March/April.

The operators ferry a combined total of almost 18,000 people into, or through, the area each year, grossing approximately $1.4 million. The predominant activities of tourists are diving, snorkelling, swimming, fishing, squidding, and seal and dolphin watching comprising most of the tourist activities in the region.

19 Glen Dibben, WA Fishing Industry Council (Inc.)

90 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 5.3 PRESSURES ON COCKBURN SOUND DUE TO ECONOMIC USES

5.3.1 Industry The main direct effects of heavy industry in the Kwinana Industrial Area on Cockburn Sound are due to discharge of industrial wastewater and—to a far lesser extent—spills during ship loading/unloading. The link between nutrient-rich wastewater discharge, seagrass loss and declining water quality in the late 1960s/early 1970s was described earlier in Sections 1.2 and 2.3.

The environmental pressures due to the shipbuilding and maintenance industries in Jervoise Bay include reclamation of foreshore, dredging, altered flushing times, physical loss of habitat (shore, seagrass, shallows), and TBT inputs.

Details on amounts of contaminants in licensed industrial discharges to the Sound from heavy industry are given in Table 5.4.

Table 5.4 Licensed industrial discharges to Cockburn Sound

CONTAMINANT AMOUNT DISCHARGED (kg/year) BP Wesfarmers Western Tiwest Joint Millenium TOTAL Refinery CSBP Power Venture Chemicals Kwinana Power Station* Flow volume 440 ML/day 17.76 ML/day Up to 1,600 4.95 ML/day 14 ML/day - ML/day Ammonium- 1,659 3,000 1,200 5,859 nitrogen Nitrate-nitrogen 7,414 6,000 13,414 Total nitrogen 12,039 28,571 9,000 3,900 1,200 54,710 Total phosphorus 2,734 3,837 200 6,771 Total suspended 53,660 52,000 94 105,754 solids Total dissolved 101,469 101,469 solids Fluoride 6,180 6,180 Sulphide 50 50 Aluminium 191 12 2,400 2,603 Arsenic 27 7 34 Cadmium 20 16 36 Chromium 1 1 Copper 20 20 360 200 600 Lead 0 16 0.3 16.3 Mercury 2 2 Nickel 10 69 79 Vanadium 0 13 300 313 Titanium 300 300 Zinc 500 397 100 80 1,077 Oil 2,747 1,800 4,547 Phenol 270 270 * Western Power discharge values are derived from net inputs of a variety of chemicals and products used at the facility, and not actual monitoring of the cooling water discharge.

New developments in the FRIARS area will also be expected to comply with best environmental practice standards.

5.3.2 Shipping The main pressures on Cockburn Sound due to commercial and RAN shipping are:

• Construction of the Causeway;

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 91 • Dredging and dredge spoil disposal; • TBT contamination; and • Introduction of foreign marine species from ballast water and ships hulls.

It is noted that the high levels of TBT presently in Cockburn Sound sediment appear to be more related to shipping maintenance areas than to commercial and naval shipping movements (see Sections 2.3.4 and 2.4.4). The CRIMP study of introduced marine pests discussed in Section 2.4.6 also indicated that the foreign marine species already introduced to FPA waters do not appear to be out-competing local biota at present, but the introduction of new foreign marine species remains a concern.

A lesser pressure from shipping is spilling of cargo during loading/unloading. There is also the potential for oil spills during bunkering, although this is minimal as bunkering is carefully managed by both the FPA20 and the RAN. Improved loading practices have also greatly reduced inputs from spillages at the FPA’s Bulk Cargo Jetty during loading/unloading. The FPA has adopted a ‘no spillage’ policy at the Bulk Cargo Jetty in the past few years, involving new drainage and bunding systems, deflector plates and unloading equipment. The DEP’s present estimate of nitrogen inputs from spills during loading/unloading is 5.6 tonnes/year, compared to an estimated 27.9 tonnes/year in the early 1990s.

5.3.3 Commercial fishing There is little environmental pressure due to commercial crabbing. The main method used for crabs has switched in recent years from gillnets to pots, the latter causing limited environmental damage due to bycatch and disturbance of the seabed. The commercial catch is a relatively small proportion of the total crab population, which is effectively renewed each year (as juveniles mature).

There is also little bycatch in the Cockburn Sound (Line and Pot) Managed Fishery and Cockburn Sound (Net) Managed Fishery, as nearly all species caught are marketed in the metropolitan area. The types of fishing gear that these two fisheries are allowed to use (see Section 5.4) involve little damage to the environment (note: trawling has been banned in Cockburn Sound since 1970). However, as noted previously (Section 4.3), there is the potential for overexploitation of some species due to combined commercial and recreational catches when recreational pressure increases. Overfishing of some species may also lead to changes in populations of non-target species due to imbalance in the food web (e.g. loss of top predator species).

The West Coast Beach Bait Managed Fishery is based on the use of specifically designed beach seine nets that are set by small dinghy and hauled by hand. There is typically very little bycatch, and as all fishing occurs over sandy substrate and fishing gear is relatively light, the impact on the seabed is minimal. Catches undergo large fluctuations (due to the variability of natural populations), but have declined in recent years, suggesting that breeding stocks may be low.

The West Coast Purse Seine Managed Fishery does not impact on the seabed, but may affect the shoreline due to access by four-wheel drives and dragging boats over the dunes. In 1995 and 1999 there were serious effects on stock due to Herpes virus, and as a result a quota of 260 tonnes (5% of the total estimated stock) has been set for the 2000/01 licensing period.

20 Details of bunkering controls and statistics on oil transfer management are available from the FPA

92 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 5.3.4 Aquaculture Mussels feed off natural phytoplankton (i.e. no feed is added to the water). Faecal wastes from the mussels can result in high organic loadings to the seabed, but the risk is assumed to be low in Cockburn Sound as the mussels are more widely spaced than elsewhere in the world (due to low phytoplankton levels). Nonetheless, the potential for organic enrichment is currently being investigated in a joint research program by the Fisheries Research Development Corp and the Aquaculture Development Fund (Penn, 2000).

The potential for adverse effects on sensitive benthic habitats due to shading effects (of the mussel lines) or organic loadings is also considered low as the lease areas are not on top of seagrass, except at the north Garden Island site (which is little used). As a positive impact, the mussel lines provide fish habitat. On the negative side, they are also viewed as an eyesore that lessens the aesthetic value of the Sound.

5.3.5 Tourism Negative effects of tourism can include disturbance to wildlife. There has also been an undesirable tendency for people to feed wild dolphins.

5.4 ENVIRONMENTAL MANAGEMENT OF ECONOMIC USES

5.4.1 Current management responses

Industry Licences for prescribed premises with the potential to cause pollution are issued by the DEP under the Environmental Protection Act, 1986. Industry are legally obliged to comply with DEP licence conditions, most of which include stringent monitoring requirements. Many industries have also developed their own Environmental Management Systems (EMS) to closely monitor all aspects of their business, and/or are voluntarily undertaking environmental best practice.

The Woodman Point WWTP is now largely self-sufficient for power (due to methane gas generated by it’s egg-shaped digesters) and is presently upgrading both storage and treatment of wastewater. After the upgrade is complete, the risk of emergency overflow into Cockburn Sound will be even less, and any wastewater discharged would be of better quality.

In a combined industry and Water Corporation exercise, it is also planned to build a Kwinana Water Recycling Plant that would process secondary treated wastewater to a standard suitable for industrial use. This water will be used by industry, and in return the Water Corporation will accept industrial wastewater into the Sepia Depression pipeline, and discharge it into less environmentally sensitive waters 4 km off Cape Peron. There will be less contaminant discharge into Cockburn Sound, and pressure will be taken off the heavily utilised groundwater resources of the region.

Commercial shipping activities Shipping activities are controlled by a number of international and commonwealth regulations.

Mandatory international regulations for the prevention of pollution from ships, are collectively known as MARPOL 73/78. MARPOL 73/78 contains detailed regulations covering the various sources of ship generated sources of marine

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 93 pollution, including oil, noxious liquid substances in bulk, by harmful substances in packaged form, sewage from ships, and garbage from ships. Australia is a full member of the International Maritime Organisation (IMO) and a signatory to MARPOL 73/78, although it is noted that Annex IV—which relates to sewage from ships—is not in force yet (adherence to the principles of Annex IV is informal at present). The Commonwealth Government’s Australian Maritime Safety Authority (AMSA) audits compliance and currency of a vessel’s certificates as issued by the IMO.

The IMO has also recently announced that it will ban application of TBT to ship’s hulls from January 2003.

At the Commonwealth Government level, from the 1st July 2001 the Australian Quarantine and Inspection Service (AQIS) will be implementing new mandatory ballast water requirements for international vessels visiting Australian waters, and for vessel movements between Australian ports. AQIS will use a risk-based decision support system that takes into account a vessel’s previous ports of call, to determine if ballast water discharge can take place and under what conditions (e.g. if ballast water treatment is needed). The decision support system is based on the findings of the CRIMP study referred to in Section 2.4.6.

Other relevant Commonwealth guidelines include:

• Australian and New Zealand Environment and Conservation Council (ANZECC) best practice guidelines for the provision of waste reception facilities at ports, marinas and boat harbours in Australia and New Zealand (ANZECC, 1996); • ANZECC code of practice for antifoulants (Hyder Consulting, 2000) for the use of all products designed to keep marine vessels and structures free of marine organisms; and • The Australian Maritime Safety Authority (AMSA) is the responsible authority for shipping of dangerous goods. Any cargoes including fuel, stores or other commodities whether packaged or in bulk, intended for carriage by sea having properties come within the classes listed in the International Maritime Dangerous Goods Code (IMDG code). Dangerous goods passing through ports must be handled in compliance with the Australian Standard AS 3846-1998 (concerning the handling and transport of dangerous cargoes in port areas).

Also, many countries (including Australia) are actively investigating alternative, more environmentally sensitive antifoulants, particularly silicone-based products that act via a non-stick surface that inhibits attachment of biota. The combination of these two activities is expected to result in a considerable reduction in TBT contamination of Australian coastal areas within the next few years.

The current Commonwealth Government position is to ban TBT use on all vessels from 1 January 2006. However, the Commonwealth Government has also specified in its Australia’s Oceans Policy that it will comply with any ban put in place by the IMO, and so the Commonwealth Government is preparing to meet the IMO’s 2003 deadline.

The Fremantle Port Authority maintains a comprehensive register that outline the relevant international, national and state legislation affecting all aspects of its operations. For example, within the National Plan to Combat Pollution of the Sea by Oil and other Noxious and Hazardous Substances, the FPA have responsibility for

94 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE implementation of the plan within its area of jurisdiction (i.e. Cockburn Sound). In particular, it is noted that the ANZECC code of practice for antifoulants has been incorporated into FPA Regulations, and in-water hull cleaning is no longer allowed to take place at berths. The FPA consider that this will have a significant effect on TBT levels in sediments at commercial jetties, and that TBT is unlikely to accumulate much in sediments due to hull leaching alone, and not at rates faster than TBT breakdown rates in sediments.

Defence shipping The Naval Waters Act applies to 500 m within Garden Island’s surrounding water.

Defence, as a Commonwealth Authority, is bound by the obligations of international treaties and Commonwealth legislation, except where expressly exempt from complying. Naval ships have been granted an immunity from MARPOL, and from the Commonwealth Protection of the Sea (Prevention of Pollution from Ships) Act 1983 which implements the provisions of MARPOL convention, but the Royal Australian Navy (RAN) seeks to comply with all relevant provisions except where emergency conditions or operational imperatives dictate otherwise.

The Commonwealth Explosives Act 1961 and Explosive Regulations 1991 specify the requirements of Defence in the transport, storage and handling of explosives by land, sea or air. There are a number of Defence policies and procedures that are specifically addressed at ensuring the RAN’s compliance with the Explosives Act, 1961 (note: The Australian Dangerous Goods Code provides guidance on transport, storage and handling of dangerous goods, but not explosives).

The RAN is committed to environmental management, and has a comprehensive environmental policy manual which sets out the RAN’s environmental obligations and commitments in all areas of environmental management and impact assessment. The Department of Defence also has an EMP in place for HMAS Stirling and Garden Island, and all activities undertaken there. As noted in Section 3.5.1, the EMP is currently being revised, and will reflect and complement initiatives at the regional level.

Defence does not have to comply with State legislation, but attempts to do so when it does not conflict with their operational imperatives (i.e. national security and national emergencies). Navy commitment to environmental management is for coexistence with State controlled areas and State legislation.

The Navy has already banned TBT use on ships less than 40 m in length, and is replacing TBT on larger warships with a copper-based paint, with a self-polishing capacity.

Commercial Fishing A restricted entry regime was introduced for Cockburn Sound in 1985, and remained in place until long-term management plans were adopted in 1995. Cockburn Sound has been a totally managed fishery since 1995.

Management of major fishing activities is achieved through formal management plans declared under the Fish Resources Management Act 1994, while other fishing activities are managed through a combination of controls from: the Fish Resources Management Regulations 1995; orders under the Act; and conditions attached to fishing boat and commercial fishing licences. Management is achieved via controls on access, boat size, catch size, and fishing gear that can be used.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 95 Commercial access to crabs in Cockburn Sound is managed under the Cockburn Sound (Crab) Management Plan, which restricts the season from December 1 to 30 September the following year, sets minimum legal crab size (well above the sexual mature size) and catch size. Due to increasing levels of competition between commercial and recreational fishers, a voluntary resource sharing agreement was recently agreed to by the fishing industry, RecFishWest, and Fisheries WA (Fisheries WA, 2000). The agreement will reduce the number of pots used by professional fishers from 1,600 to 800 over three years, or will achieve a share of the catch of five-eighths commercial and three-eighths recreational.

For finfish, octopus and squid, the methods allowed under the Cockburn Sound (Line and Pot) Managed Fishery and Cockburn Sound (Net) Managed Fishery include handline, longline, unbaited octopus pots, squid jigging, gill net, beach seine and haul net (trawling has been banned since 1970). There was a temporary closure for line fishing between 15th September and 31st October 2000 during snapper spawning season.

The Cockburn Sound (Mussel) Managed Fishery is managed in accordance with an agreement between the Minister for Fisheries and the Fremantle Port Authority (to ensure navigational marking requirements are met).

Management of the West Coast Beach Bait Managed Fishery operates in waters from Lancelin to Tims Thicket (near Mandurah) is by limited entry licence, and the use of specifically designed beach seine nets that are set by small dinghy and hauled by hand. There is typically very little bycatch, and as all fishing occurs over sandy substrate and fishing gear is relatively light, the impact on the seabed is minimal. Catches undergo large fluctuations (due the variability of natural populations), but have declined in recent years, suggesting that breeding stocks may be low.

The West Coast Purse Seine Managed Fishery is managed under the provisions of the West Coast Purse Seine Management Plan 1989. Management is currently based on limited entry and controls on gear and boat size, but serious impacts on stock in 1995 and 1999 due to Herpes virus led to the Minister setting a quota of 260 tonnes (5% of the total estimated stock) for the 2000/01 licencing period. Arrangements are underway to change management to a quota basis, but this has yet to be legislated. The extent of impacts on coastal areas due to vehicle and boat access is not known.

Aquaculture All aspects of aquaculture are carefully controlled under a Shellfish Quality Assurance Program. Freedom from contamination and meticulous hygiene are essential for successful marketing of the product.

Tourism The charter fishing industry came under management by Fisheries WA for fish catches in July 2000, following a major review of charter fishing and associated ecotourism.

5.4.2 Gaps in the management responses No gaps apparent.

96 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 5.4.3 Gaps in information needed for management As noted in Section 4.4 on recreational fishing, information is needed on the combined commercial and recreational catches, and on links with adjacent areas such as the Swan river, to improve management.

There may be a need to offset increased recreational fishing with reduced commercial fishing. This could be achieved for some fisheries by re-adjustments to number of licences through voluntary buy-back. This is a response often used in the management of areas of high recreational pressure, such as estuaries.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 97

6. RECOMMENDED RESEARCH AND INVESTIGATION PROGRAMME The following suggestions for research and investigation are based on the information gaps identified in previous sections. Within each section, suggestions are listed in approximate order of management priority.

6.1 MARINE • An agreed conceptual model of the effects of nutrient inputs to Cockburn Sound; • Up-to-date data on sediment characteristics in Cockburn Sound, particularly the levels of nutrients, organic matter and chlorophyll a (the latter being an indication of MPB growth); • An agreed method for evaluating cumulative impacts; • Additional data to improve modelling of water movement and coastal processes in Cockburn Sound. In particular: Long-term wave data. Minimum requirements of two wave measurement sites within Cockburn Sound (one in southern region, one in northern region) and one offshore (already in operation). This will be particularly useful in interpreting changes in sediment transport in the Sound; and Long-term current meter deployments, also collecting temperature and salinity data, at the northern and southern entrances to Cockburn Sound. • A standard approach for assessing coastal erosion measures and adapting them for local conditions; • Maintain and expand current monitoring of nutrient-related water quality in summer (currently undertaken by the Kwinana Industries Council), seagrass health every year and seagrass distribution every three years (currently undertaken by the DEP); • Studies on the local populations of fish, crabs and the connections between those local populations, the fisheries, and adjacent areas such as the Swan River; and • The influence of the Causeway on the environmental quality of the Sound, and the potential environmental benefits of modifying its design.

The first four items are of the highest priority, and it is strongly recommended that they are discussed in a workshop attended by relevant government and scientific personnel, to refine and agree on the key data requirements.

6.2 LAND • A catchment management programme for Cockburn Sound; • An inventory of contaminated sites; • Mapping of storm water catchments around the urbanised areas of Rockingham and Kwinana and the identification of discharges to the Sound; and • A systematic approach to quantifying the quality of groundwater discharging to Cockburn Sound (to be developed in cooperation with industries fringing the Sound), using a standard suite of analytes.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 99 6.3 SOCIAL AND CULTURAL • A comprehensive survey that establishes types, areas and intensity of recreational use; and • Better estimates of recreational catches, both boat-based and shore-based, for integrated catch management of fisheries, particularly when recreational fishing pressure rises with population increases.

100 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 7. REFERENCES AND FURTHER RECOMMENDED READING AMISC (1997). Marine Industry Development Strategy. Canberra, Department of Industry, Science and Tourism.

Andrews, W (1979). Shoreline Stability - Fremantle to Cape Peron, Department of Marine and Harbours.

Annandale, D (1999). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrasses. Socio-Economic Uses and Values, Phase 3 Report, Prepared for Cockburn Cement Ltd, Perth, Western Australia.

ANZECC (1996). Best Practice Guidelines for the Provision of Waste Reception Facilities at Ports, Marinas and Boat Harbours in Australia and New Zealand, Australian and New Zealand Environment and Conservation Council.

ANZECC/ARMCANZ (2001). Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Appleyard, S J (1994). The discharge of nitrogen and phosphorus from groundwater into Cockburn Sound, Perth Metropolitan Region., Geological Survey WA, Perth, Western Australia.

Appleyard, S J & Haselgrove, K (1995). Groundwater Discharge of Nutrients to a Sheltered Marine System: Data Uncertainty and Constraints on Management. Australian Systems Conference, Perth, Western Australia.

Australian Heritage Commission (1997). Registrar of the National Estate Database Place Report - Beeliar Park and Adjacent Areas, Australian Heritage Commission, Canberra.

Ayvazian, S G & Hyndes, G A (1995). “Surf-Zone Fish Assemblages In South- Western Australia: Do Adjacent Nearshore Habitats and the Warm Leeuwin Current Influence the Characteristics of the Fish Fauna?” Marine Biology 122: 527-536.

Ayvazian, S G, Lenanton, R, Wise, B, Steckis, R & Nowara, G (1997). Western Australian Salmon and Australian Herring Creel Survey, Fisheries Department of Western Australia and Fisheries Research & Development Corporation.

Barker and Associates (2000). Waste to Energy and Water Plant, Lot 15 Mason Road, Kwinana, Public Environmental Review, Global Olivine, Perth, Western Australia.

Bastyan, G & Paling, E (1995). Experimental Studies on Coastal Sediment Nutrient Release and Content, Report to CSBP February, 1995.

Beckwith and Associates (1995). Cultural Uses of the Southern Metropolitan Coastal Waters of Perth, Prepared for the Environmental Protection Authority of Western Australia by Beckwith and Associates Environmental Planning, Perth, Western Australia.

Bell, J D & Pollard, D A (1989). Ecology of Fish Assemblages and Fisheries Associated with Seagrasses. Biology of Seagrasses: A Treatise on the Biology

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 101 of Seagrasses with Special Reference to the Australian Region. A. W. D. Larkum, A. J. McComb & S. A. Sheperd, Elsevier, Amsterdam.

Brearley, A & Wells, F E (2000). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrasses. Invertebrates, Phase 3 Report, Report prepared for Cockburn Cement Limited, Western Australia.

Brooker, M G, Smith, G T, Leone, J & Ingram, J A (1995b). “A Biological Survey of Garden Island, Western Australia. Terrestrial Mammals.” Western Australian Naturalist 20: 211-220.

Brooker, M G, Smith, G T, Saunders, D A & Ingram, J A (1995a). “A Biological Survey of Garden Island, Western Australia. Birds and Reptiles.” Western Australian Naturalist 20: 169-184.

BSD (1999). Consultative Environmental Review Development of Lots 165 and 168 Cockburn Road, Henderson. Seawall Construction, Land Reclamation, and Dredging Adjacent to Lots 165 and 167. Including Lots 166 and 168, and Management of Shipbuilding, Repair and Maintenance activities at Cockburn Sound, Cockburn Road, Henderson., Prepared for Land Corp.

CALM (1994). A Representative Marine Reserve System for Western Australia. Report of the Marine Parks and Reserves Working Group., Department of Conservation and Land Management, Perth, Western Australia.

Cambridge, M L (1979). Cockburn Sound Environmental Study. Technical Report on Seagrass., Department of Conservation and Environment, Perth, Western Australia.

Cambridge, M L & McComb, A J (1984). “The Loss of Seagrasses in Cockburn Sound, Western Australia. I. The Time Course and Magnitude of Seagrass Decline in Relation to Industrial Development.” Aquatic Botany 20: 229-243.

Chalmers, L (1993). Disturbance of benthic fauna in Cockburn and Warnbro Sounds, Western Australia. Department of Geography, University of Western Australia, Nedlands, Western Australia.

Chaney, J A (1978). Studies on Phytoplankton in Cockburn Sound. Botany Department, University of Western Australia, Nedlands, Western Australia.

Chegwidden, A (1979). Technical Report on Distribution of Contaminants, Report to the Cockburn Sound Study Group by the Department of Conservation and Environment, Perth, Western Australia.

Chiffings, A W (1979). Cockburn Sound Study, Technical Report on Nutrient Enrichment and Phytoplankton, Department of Conservation and Environment, W.A. Report No. 3.

Chiffings, A W (1987). Nutrient Enrichment and Phytoplankton Response in Cockburn Sound, Western Australia. Botany, University of Western Australia, Perth, Western Australia.

102 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE City of Rockingham (2000). State of the Environment Report and Environmental Action Plan (Draft) 2000-2001.

Cockburn Cement Ltd (2000). Long-term Shellsand Dredging, Owen Anchorage. Environmental Review and Management Programme.

Commonwealth of Australia (1992). National Strategy for Ecologically Sustainable Development, Australian Government Publishing Service, Canberra, Australia.

Commonwealth of Australia (1995). Our Sea, Our Future. Major findings of the State of the Marine Environment Report for Australia, Great Barrier Reef Marine Park Authority for Department of the Environment, Sport and Territories, Canberra, Australia.

Commonwealth of Australia (1996a). The National Strategy of the Conservation of Australia's Biological Diversity, Department of the Environment, Sport and Territories, Canberra, Australia.

Commonwealth of Australia (1998). Australia's Ocean Policy, Environment Australia, Canberra, Australia.

CRIMP (2000). Introduced Species Survey Final Report: Fremantle, Western Australia.

CSIRO (1996). Port Phillip Bay Study. Final Report, CSIRO, Dickson, ACT, Australia.

D'Adamo, N (1992). Hydrodynamics and Recommendations for Further Studies in Cockburn Sound and Adjacent Waters. Perth, Western Australia, Environmental Protection Authority.

D'Adamo, N & Mills, D A (1995). Field Measurements and Baroclinic Modelling of Vertical Mixing and Exchange During Autumn on Cockburn Sound and Adjacent Waters, Western Australia, Department of Environmental Protection Technical Series 67, December 1995.

DAL (1999). Estimates of Nitrogen Loading to Jervoise Bay, Northern Harbour. Nedlands, Western Australia, Prepared by D.A. Lord & Associates Pty Ltd for the Department of Commerce and Trade, and the Water Corporation.

DAL (2000). Circulation Between Owen Anchorage and Cockburn Sound. Implications for Water Quality and Light Attenuation. Perth, Western Australia, Report prepared by D.A. Lord & Associates Pty Ltd for Cockburn Cement Limited.

DAL (2001). Kwinana Power Station Combined Cycle Plant Thermal Plume Study: Field Data and Modelling Report, Report to Western Power Corporation.

DAL, e a (2000). Seagrass Mapping Owen Anchorage and Cockburn Sound 1999, Prepared by D.A. Lord & Associates Pty Ltd; Botany Department, University of Western Australia; Alex Wyllie and Associates Pty Ltd; NGIS Australia Pty Ltd; and Kevron Aerial Surveys Pty Ltd. Prepared for Cockburn Cement Limited; Department of Environmental Protection; Department of Commerce and Trade; Department of Resources Development; Fremantle Port Authority;

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 103 James Point Pty Ltd; Kwinana Industries Council; Royal Australian Navy; Water Corporation; and Water and Rivers Commission.

Dames and Moore (1996). Consultative Environmental Review for Kwinana Ammonia Project, Prepared for Wesfarmers CSBP Ltd.

Davidson, W A (1995). Hydrogeology and Groundwater Resources of the Perth Region, Western Australia, Geological Survey of Western Australia.

DCE (1979). Cockburn Sound Environmental Study: 1976-1979, Prepared by the Department of Conservation and Environment, Perth, Western Australia.

Dennison, W C & Abal, E G (1999). Moreton Bay Study. A Scientific Basis for the Healthy Waterways Campaign. Brisbane, Queensland, Prepared for the South East Queensland Regional Water Quality Management Strategy: 246p.

DEP (1996). Southern Metropolitan Coastal Waters Study, Final Report. Perth, Western Australia, Prepared by the Department of Environmental Protection.

DEP (1998). State of the Environment Report.

DEP (2000). Annual Report 1999-2000: 100-101.

Dielesen, L (1994). South West Metropolitan Beach Survey, Unpublished Report. South West Groups, Kwinana, Western Australia.

DMH (1992). Mangles Bay Marina: Public Environmental Review, Report of the Western Australian Department of Marine and Harbours.

DOT (1999). Recreational Boating Facilities in Western Australia - A Study of User Needs, Report prepared by Market Equity Pty Ltd for the Department of Transport, Perth, Western Australia.

Dybdahl, R E (1979). Cockburn Sound Study. Technical Report on Fish Productivity. Perth, Western Australia, Department of Conservation and Environment.

Edgar, G J & Shaw, C (1993). Inter-Relationships Between Sediments, Seagrasses, Benthic Invertebrates and Fishes in Shallow Marine Habitats off South- Western Australia. The Marine Flora and Fauna of Rottnest Island, Western Australia. Volume 2. F. E. Wells, D. I. Walker, H. Kirkman & R. Lethbridge, Western Australian Museum, Perth, Western Australia.

Environment, D o C a (1979). Cockburn Environmental Study, 1976-1979.

Environment, D o C a (1979). Cockburn Sound Environmental Study 1976-1979, Report No. 2.

EPA (1983). Conservation Reserves for Western Australia. The Darling System - System Six. Part II: Recommendations for Specific Localities. Perth, Western Australia, Department of Conservation and Environment.

104 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE EPA (1991). Protecting Perth's Coastal Waters and Beaches. Perth, Western Australia, The Environmental Protection Authority and the Water Authority of Western Australia. Environmental Protection Authority.

EPA (1993). Western Australian Water Quality Guidelines for Fresh and Marine Waters. Perth, Western Australia, Environmental Protection Authority.

EPA (1994). Proposed Short-Term Continuation of Dredging Shellsand on Success Bank, Owen Anchorage; and Proposed Strategy to Address the Long-Term Environmental Issues of Shellsand Dredging. Perth, Western Australia, Report and Recommendations of the Environmental Protection Authority.

EPA (1998). Guidance for the Assessment of Environmental Factors (In Accordance with the Environmental Protection Act 1986). Draft Policy No. 22: Seagrass Habitat Protection. Perth, Western Australia, Environmental Protection Authority.

EPA (1998). Industrial Infrastructure and Harbour Development, Jervoise Bay, Department of Commerce and Trade.

EPA (1998). Kwinana Ammonia Project, Kwinana Industrial Area.

EPA (1998). The Marine Environment of Cockburn Sound. Strategic Environmental Advice.

EPA (1999). Kwinana Export Facility, Kwinana, Koolyanobbing Iron Pty Ltd, Fremantle Port Authority, and Westrail.

EPA (1999). Seawall construction, land reclamation and dredging adjacent to Lots 165 and 167, including Lots 166 and 168, and management of shipbuilding, repair and maintenance activities at Cockburn Sound, Cockburn Road, Henderson.

EPA (2000). Perth's Coastal Waters. Environmental Values and Objectives. The Position of the EPA - A Working Document. Perth, Western Australia, Environmental Protection Authority.

EPA (2000). Waste to Energy and Water Plant, Lot 15 Mason Road, Kwinana.

ERA (1972). Beach Morphology of Cockburn Sound, Autumn 1971, Report by Environmental Resources of Australia Pty Ltd to Commonwealth Department of Works.

ERA (1973). Beach Morphology Cockburn Sound. July-December 1972, Report prepared by Environmental Resources of Australia Pty Ltd for Commonwealth Department of Works.

Feilman & Associates (1978). Cockburn Sound Recreation Survey. Perth, Western Australia, Report to the Cockburn Sound Study Group by the Department of Conservation and Environment.

Field, S (1993). The Use of Thais orbita as a Bioindicator for Environmental Contamination of Tributyltin in the Perth Metropolitan Waters. Zoology Department. Nedlands, Western Australia, University of Western Australia.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 105 Fisheries WA (2000). No Snags in Cockburn Crab Share Initiative. Perth, Western Australia, Fisheries.

FPA (2000). Fremantle Port Annual Report Year 2000, Annual Report of the Fremantle Port Authority, Western Australia.

Gales, N J, Shaughnessy, P D & Dennis, T E (1994). “Distribution, abundance and breeding cycle of the Australian sea-lion Neophoca cinerea.” Journal of Zoology, London 234: 353-370.

Garret, D & Souter, C (1997). Jervoise Bay Project Report - A survey of the shipwrecks Abemama and SS Alacrity, Department of Maritime Archaeology, Western Australian Maritime Museum.

Geological Survey of Western Australia (1985). “1:50,000 Environmental Geology Series. Fremantle, 1985.”.

Gibson, N, Keighery, B J, Burbidge, A H & Lyons, M N (1994). A Floristic Survey f the Southern Swan Coastal Plain, Unpublished Report for the Australian Heritage Commission prepared by the Department of Conservation and Land Management for the Conservation Council of Western Australia.

Glover, E A & Taylor, J D (1999). Diversity and Distribution of Subtidal Macromolluscs around Rottnest Island, Western Australia. The Seagrass Flora and Fauna of Rottnest Island, Western Australia. D. I. Walker & F. E. Wells, Western Australian Museum: pp 101-119.

Hale, J & Paling, E (1999). Water Quality of Cockburn Sound (December 1998 to March 1999), A draft report to the Kwinana Industry Council from the Marine and Freshwater Research Laboratory, Murdoch University.

Hale, J, Wilson, C & Paling, E (1998). Water Quality of Cockburn Sound, A Report to the Kwinana Industry Council prepared by the Marine and Freshwater Research Laboratory, Murdoch University.

Haselgrove, K (1981). The Effects of Groundwater Use by Industry at Kwinana. Symposium on the Groundwater Resources of the Swan Coastal Plain, CSIRO.

Hearn, C J (1991). A Review of Past Studies of the Hydrodynamics of Cockburn Sound and Surrounding Waters with an Appraisal of Physical Processes and Recommendations for Future Data Collection and Modelling., Report to the Environmental Protection Authority.

Helleren, S & John, J (1995). Phytoplankton and Zooplankton and Their Interactions in the Southern Metropolitan Coastal Waters off Perth, Western Australia. Bentley, Western Australia, Report to the Department of Environmental Protection by the School of Environmental Biology, Curtin University of Technology.

HGM (1997). Industrial Infrastructure and Harbour Development, Jervoise Bay, Public Environmental Review, Prepared on behalf of the Department of Commerce and Trade in association with LandCorp and Main Roads Western Australia.

106 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE HGM (1998a). Investigation of Water Quality in the Jervoise Bay, Northern Harbour (December 1997-March 1998), Report to the Department of Commerce and Trade.

HGM (1998b). Declared Rare Flora Survey - Industrial Infrastructure Section, Jervoise Bay, Unpublished report for the Department of Commerce and Trade.

Hine, P T (1998). Contaminant Inputs Inventory of the Southern Metropolitan Coastal Waters of Perth: An Update - June 1998, Unpublished Report for the Department of Environmental Protection.

How, R A, Dell, J & Waldock, J M (1996). Ground fauna of Urban Bushland Remnants in Perth, Unpublished report to the Australian Heritage Commission.

Hsu, J R C (1992). Foreshore Restoration: North of James Point, Report to BP Refinery (Kwinana) Pty Ltd, Unpublished Report: 21pp.

Hyder Consulting (2000). Consultancy on Antifouling: Draft Code of Practice, Prepared for Australian New Zealand Environment and Conservation Council.

Hyndes, G A, Kendrick, G W, MacArthur, L & Stewart, E (2000). Shellsand Dredging Environmental Management, Project S1: Ecological Significance of Seagrasses. Fish and Fishery, Phase 3 Report, Report prepared for Cockburn Cement Ltd, Perth, Western Australia.

Jacoby, C, Griffiths, B, Braine, S & Jernakoff, P (2000). Seagrass Monitoring at HMAS Stirling. HMAS Stirling Environmental Working Paper No. 13., Prepared for the Garden Island Advisory Committee by CSIRO.

Jacoby, C, Syme, G & Colgan, P (1999). Perth Coastal Waters Public Involvement Process: Environmental Values, Environmental Quality Objectives, draft Environmental Quality Zones. Volumes 1 and 2, CSIRO Division of Water Resources, Floreat Park, Western Australia.

Johnstone, R E & Storr, G M (1998). Handbook of Western Australian Birds: Volume 1 - Non-Passerines (Emu to Dollarbird), Museum of Western Australia, Francis St, Perth, Western Australia.

Jonker, L J (1993). Comparison of the Larval Fish Assemblages in Healthy and Degraded Seagrass Meadows in Cockburn Sound, Western Australia. Biology, Murdoch University, Perth, Western Australia.

JPPL (2001). James Point Port: Stage 1, James Point, Cockburn Sound. Public Environmental Review., James Point Pty Ltd.

Keighery, B J (1996). Objection Assessment of the Values of the Vegetation and Flora of the Beeliar Wetlands, Unpublished report for the Australian Heritage Commission.

Keighery, B J, Gibson, N & Keighery, G (1997). The Regional Significance of the Flora and Vegetation of Garden Island, Papers of the Environment and Energy Conference, HMAS STIRLING 14-15 April 1997, Department of Defence.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 107 Keighery, G J & Keighery, B J (1993). Part IX: The Flora of Three Coastal Bushland Areas (System 6 Areas M46, M91 and M106). Floristics of Reserves and Bushland Areas of the Perth Region (System 6). Parts V-IX. G. J. Keighery & B. J. Keighery, Wildflower Society of WA (Inc.), Nedlands, Western Australia.

Kenderdine, S (1995). A Guide to the Historic Wreck Sites of Perth, Western Australian Maritime Museum, Perth, Western Australia.

Kendrick, G A (2000). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrasses. Habitat Complexity, Phase 3 Report, Report prepared for Cockburn Cement Ltd, Perth, Western Australia.

Kendrick, G A, Campey, M, Lavery, P, Westera, M & Wheeler, K (2000). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrass. Primary Production, Phase 3 Report, Report prepared for Cockburn Cement Ltd, Perth, Western Australia.

Kinhill Pty Ltd (1998a). Modelling of the Circulation and Flushing within Cockburn Sound - Part 1., Prepared for the Department of Environmental Protection, Perth, Western Australia.

Kinhill Pty Ltd (1998b). Modelling of the Circulation and Flushing within Cockburn Sound - Part 2, Prepared for the Department of Environmental Protection, Perth, Western Australia.

Klumpp, D W, Howard, R K & Pollard, D A (1989). Trophodynamics of Nutritional Ecology of Seagrass Communities. Biology of Seagrasses: A Treatise on the Biology of Seagrasses with Special Reference to the Australian Region. A. W. D. Larkum, A. J. McComb & S. A. Sheperd, Elsevier, Amsterdam: 394-457.

Latchford, J, Wilshaw, J & Paling, E (1997). Water Quality of Cockburn Sound (November 1996-March1997) (Draft): Commissioned to the Kwinana Industry Council, Institute for Environmental Science, Murdoch University, Perth, Western Australia.

Lavery, P, Vanderklift, M, Hyndes, G A & Brearley, A (2000). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrasses. Flora and Fauna Diversity, Phase 3 Report, Report prepared for Cockburn Cement Ltd, Perth, Western Australia.

Lemm, A (1997). Offshore Wave Climate Perth, Western Australia 1994-1998. 14th Australasian Coastal and Ocean Engineering Conference.

Lenanton, R (1982). “Alternative Non-Estuarine Nursery Habitats for some Commercially and Recreationally Important Fish of South-Western Australia.” Australian Journal of Marine and Freshwater Research 33: 881-900.

Lenanton, R & Caputi, N (1989). “The Roles of Food Supply and Shelter in the Relationship Between Fishes in Particular Cnidoglanis macrocephalus Valenciennes and Detached Macrophytes in the Surf Zone of Sandy Beaches.” Journal of Experimental Marine Biology and Ecology 128(2): 165-176.

108 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Lenanton, R, Robertson, A I & Hansen, J A (1982). “Nearshore Accumulations of Detached Macrophytes as Nursery Areas for Fish.” Marine Ecology Progress Series 9: 51-57. Lord, D, Paling, E & Gordon, D (1999). Review of Australian rehabilitation and restoration programs. Seagrass in Australia. A. Butler & P. Jernakoff, CSIRO Publishing, Collingwood, Victoria, Australia: pp 65-115.

Lukatelich, R J, Bastyan, G, Walker, D I & McComb, A J (1987). Effect of Boat Moorings on Seagrass Beds in the Perth Metropolitan Region, Department of Botany and Centre for Water Research, University of Western Australia, Perth, Western Australia.

Martinick and Associates & Mackie Martin and Associates (1993). Contaminant Inputs Inventory of the Southern Metropolitan Coastal Waters of Perth, Report to the Environmental Protection Authority.

McAlpine, K & Masini, R (2001). Perth's Coastal Waters: Development of Environmental Quality Criteria. A Supporting Document for the Technical Workshops, Report prepared for the Department of Environmental Protection.

Mills, D A & D'Adamo, N (1995). The Application of a Three-Dimensional Baroclinic Model to the Hydrodynamics and Transport of Cockburn Sound, Western Australia, and Surrounding Waters, Technical Series No. 76, Department of Environmental Protection, Perth, Western Australia.

Muriale, O & Cary, J L (1995). Contaminant Inputs Inventory of the Southern Metropolitan Coastal Waters of Perth: An Update, Department of Environmental Protection.

Nield Consulting (1999). Modelling of the Superficial Aquifer in the Cockburn Groundwater Area, Report for the Waters and Rivers Commission/Kwinana by the Groundwater Investigation Branch of the Waters and Rivers Commission.

Passmore, J R (1970). Shallow Coastal Aquifers in the Rockingham District, Water Research Foundation of Australia.

Pattiaratchi, C B, Imberger, J, Zaker, N & Svenson, T (1995). Perth Coastal Waters Study: Physical Measurements. Project P2, Prepared by the Centre for Water Research for the Water Authority of Western Australia.

Pearce, A, Helleren, S & Marinelli, M (2000). Review of Productivity Levels of Western Australia Coastal and Estuarine Waters for Mariculture Planning Purposes, Western Australian Marine Research Laboratories, Fisheries Western Australia.

Penn, J W (1977). Trawl Caught Fish and Crustaceans from Cockburn Sound, Department of Fisheries and Wildlife of Western Australia, Report No. 20.

Penn, J W (1998). State of the Fisheries Report 1997/1998, Fisheries Western Australia, Perth, Western Australia.

Penn, J W (1999). State of the Fisheries Report 1998/1999, Fisheries Western Australia, Perth, Western Australia.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 109 Penn, J W (2000). State of the Fisheries Report, 1999/2000, Fisheries Western Australia.

PHC (2000). Preliminary Review. Project C4: Effects of Patterns of Circulation and Water Exchange from the Construction of a Seaway Through Success and Parmelia Banks, Prepared on behalf of Cockburn Cement by Port & Harbour Consultants.

Powell, R & Emberson, J (1981). Woodman Point. A Relic of Perth's Coastal Vegetation, Artlook, Western Australia.

PPK (1998a). Nitrogen Discharges into Jervoise Bay from Groundwater, Hydrochemical Study, Halpern Glick Maunsell.

PPK (1998b). Nitrogen Discharges into Jervoise Bay from Groundwater, Hydrochemical Monitoring, Halpern Glick Maunsell.

PPK (1999a). Remediation Strategy for Nitrogen Rich Groundwater at Jervoise Bay, Department of Commerce and Trade. PPK (1999b). Jervoise Bay Monitoring Bores - Hydrochemical Monitoring and Water Levels September 1999, Department of Commerce and Trade.

Robinson, D, Maryan, B & Browne-Cooper, R (1987). “Herpetofauna of Garden Island.” Western Australian Naturalist 17: 11-14.

Rogers & Associates (1999). Woodman Point West Beach - Stage 1 Report, Report R071 Rev 0 prepared for the Department of Commerce and Trade.

Rogers & Associates (2000). Effects of the Proposed Seaway & Mewstone Dredging, Report prepared for Cockburn Cement Ltd by M.P. Rogers & Associates, Perth, Western Australia.

Saxby, S (submitted). A Review of Literature Concerning Bivalve Growth and Condition, Food Availability and Water Conditions, at Commercial Growth Sites, WA Fisheries Research Report.

Sciences, B E (2000). Lot 52 Burns Beach Road Fauna Survey., Unpublished report prepared for Setoma Pty Ltd.

Scott, J K, Dybdahl, R E & Wood, W F (1986). The Ecology of Posidonia Seagrass Fish Communities in Cockburn Sound, Western Australia, Department of Conservation and Environment, Perth, Western Australia.

Smit, A J, Brearley, A, Hyndes, G A & Lavery, P (2000). Shellsand Dredging Environmental Management Programme, Project S1: Ecological Significance of Seagrasses. Trophic Structure and Linkages, Phase 3 Report, Report prepared for Cockburn Cement Ltd, Perth, Western Australia.

Spencer, I K (1993). Nutrient Input into the Southern Perth Waters through Submarine Discharge. Environmental Engineering, University of Western Australia, Perth, Western Australia.

110 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE Sumner, N R & Williamson, P C (1999). A 12-month Survey of Coastal Recreational Fishing Between Augusta and Kalbarri on the West Coast of Western Australia During 1996-97, Fisheries Western Australia.

Thomas, G A & Evans, C A (1995). Alcoa Internal Report.

Vanderklift, M (1996). Influence of Adjacent Seagrass on the Fish Assemblages off Sandy Beaches. Environmental Management, Edith Cowan University, Perth, Western Australia.

WAPC (1999). Draft Statement of Planning Policy No. 10 Basic Raw Materials, Western Australian Planning Commission, Perth, Western Australia.

WAPC (2000a). Fremantle-Rockingham Industrial Area Regional Strategy. Final Report., Prepared by Environmental Resources Management Australia Pty Ltd (ERM) in conjunction with Connell Wagner and Economic Research Associates, for the WA Planning Commission, Perth, Western Australia.

WAPC (2000b). Bush Forever: Keeping the Bush in the City, Report by the WA Planning Commission, Perth, Western Australia.

Western Fisheries (2001). WA's Journal of Fishing and the Aquatic Environment. Autumn, 2001, Fisheries Western Australia.

Wilson, B R, Kendrick, G W & Brearley, A (1978). The Benthic Fauna of Cockburn Sound, Western Australia. Part 1: Prosobranch Gastropod and Bivalve Molluscs, Unpublished Report by the Western Australian Museum to the Department of Conservation and Environment, Perth, Western Australia.

Wykes, B J, Pearson, D & Maher, J (1999). Fauna Survey of Garden Island, WA, 1996-1997., Environmental Working Paper No. 12, Garden Island Environmental Advisory Committee.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 111

8. ACKNOWLEDGMENTS This report was prepared by Karen Hillman, Guy Gersbach, Mark Bailey, Helen Astill (D.A. Lord & Associates Pty Ltd) and John Throssell (PPK Environment & Infrastructure Pty Ltd). Report preparation and cover design was by Emma Newark (D.A. Lord & Associates Pty Ltd). The following people also gave freely their time and expertise, and are acknowledged with much pleasure:

• Professor George Kailis (Chairman, Cockburn Sound Management Council); • Anthony Sutton and Heidi Bucktin (Cockburn Sound Management Council); • Bryan Jenkins, Ray Masini, Philip Hine and Steve Watson (Department of Environmental Protection); • Steve Wade, Gino Vallenti, Rod Townsend and Lee Woolhouse (Fremantle Port Authority); • Ross Marshall and David Ryan (Department of Commerce and Trade); • Don Martin (Department of Resources Development); • Petrina Raitt (Department of Transport); • Tony Cappelluti, Eve Bunbury, Rod Lenanton, Neil Sumner, Suzy Ayvazian, Gabrielle Nowara, Dan Gaughan, Ron Mitchell, Tim Leary, , Eva Lai and Mervi Kanga (Fisheries WA); • Amanda Stanithorpe (Ministry for Planning); • Steve Appleyard and Michelle Crean (Water and Rivers Commission); • Mike Pokucinski (Water Corporation); • Mike McCarthy (Maritime Museum); • Fred Wells (WA Museum); • Lieutenant Commander Robert Walker (Port Manager, HMAS Stirling); • Boyd Wykes (Defence Estate Organisation WA); • Kirsty Stratford (City of Cockburn); • Rosalind Murray (Town of Kwinana); • Garry Middle (City of Rockingham); • John Smedley (Cockburn Power Boat Association); • Norm Halse (RecFishWest); • Tarren Reitzema (School of Public Health, Curtin University); • Monique Gagnon (Department of Environmental Biology, Curtin University); • Eric Paling, Jenny Hale and Hugh Finn (Biological and Environmental Sciences, Murdoch University); • Paul Lavery and Glenn Hyndes (Department of Environmental Management Edith Cowan University); • Garth Humphreys (Biota Environmental Sciences Pty Ltd); • Stuart Helleren (Dalcon Environmental); • David Hearn (Division of Land and Water CSIRO); • Gavin Jackson (Gavin Jackson Pty Ltd); • Murray Burling (Port and Harbour Consultants); • John Polglaze (URS Australia Pty Ltd); • Martin Taylor (Chamber of Commerce and Industry); • Mike Baker (Kwinana Industries Council); • Rod Lukatelich and Andrew King (BP Refinery (Kwinana) Pty Ltd);

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 113 • Cameron Schuster and Mark Germain (Wesfarmers CSBP); • Steve Genoni (Alcoa World Alumina); • Grant Robinson (Coogee Chemicals); • Peter Tichelaar (Millennium Performance Chemicals); • Bruce Cadee (Nufarm Coogee); • Chris Lee (Nufarm Ltd); • Cheryl Willets (Tiwest Joint Venture); • Bruce Talbot (WMC Resources); and • Peter Christian (Western Power).

114 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 9. GLOSSARY

Aeolian Transported by wind. Algae Non-flowering aquatic plants. The larger plants of this group that occur in marine environments, are called seaweed and the microscopic plants that float in the water are called phytoplankton. Anaerobic Without oxygen. Anthropogenic Resulting from human activity Aquatic Growing or living in or near water. Aquifer A layer of rock or soil capable of holding or transmitting water. Assemblage Recognisable grouping or collection of individuals or organisms. Bathymetry Measurement of the changing ocean depth to determine the sea floor topography. Beneficial uses The ways a society uses or values an area (synonymous with environmental values). Benthic Associated with the seabed (usually refers to fauna) Bioaccumulation The accumulation of contaminants in organisms at levels above that of the ambient environment. Biodiversity The variety of all life forms: the different plants, animals and microorganisms, the genes they contain and the ecosystems they form. Biota Defined as all plants, animals and microorganisms of a region. Biomass The living weight of a plant or animal population, usually expressed on a unit area basis. CD Chart Datum. The plane or level to which surroundings (or elevations) or tide heights are referenced. Used to provide a safety factor for navigation and usually a level lower than mean sea level. Chlorophyll a A complex molecule that along with other similar molecules, is able to capture sunlight and convert it into a form that can be used for photosynthesis. All plants contain chlorophyll a and the concentration of this molecule in water is commonly used as a measure of phytoplankton biomass. Colonisation Movement of an organism into an area in which it was not previously present. Compliance The degree to which stated project goals or requirements are attained. Contamination Introduction of physical, chemical or biological substance or properties into the environment by human activities (c.f. pollution). Diffusion The transfer of substances from regions of high concentrations to regions of lower concentrations. Diurnal Daily. Ecological function Combined characteristics and processes occurring within an area. Ecology Studies of the relations of animals and plants, particularly of animal and plant communities, to their surroundings. Ecosystem A community of organisms, interacting with each other plus the environment in which they live and with which they also interact. Ecosystem integrity The ability to support and maintain a balanced, integrative, adaptive community of organisms having a species composition, diversity and functional organisation comparable to that of natural habitat of the region. e-folding time A means of measuring the flushing of a water body with water sourced from outside the water body. The e-folding time is calculated by measuring the time taken for a conservative tracer (see above), initially located solely in the water body of interest to be diluted to 1/e (=0.368) of its original concentration. Environmental The scientific benchmarks upon which a decision may be made concerning the ability quality criteria of an environment to maintain certain designated environmental quality objectives. Environmental The long-term goals of an environmental management programme in relation to the quality objectives maintenance of the environmental (ecological and cultural) values of natural systems. Environmental The ways a society uses or values an area (synonymous with beneficial uses). values Epiphyte Plant that grows attached to the outside of another plant. Eutrophic Nutrient enriched (usually associated with deterioration of natural water bodies where nutrient enrichment occurs through man’s activities). Eutrophication An increase in the rate of supply of organic matter to an ecosystem caused by unnaturally high loads of nutrients to that system. Fauna Animals. Flora Plants. Gyre Rotation, spinning motion. Used to describe large circular movement of water. Habitat The place or environment occupied by individuals of a particular species, population or community; has physical, chemical and biological attributes conducive to the maintenance and propagation of those biota. Heavy metals Such as zinc, copper, chromium which accumulate in sediments and tissues of biota, and may be passed-up in the food chain. Heavy metals can be toxic at high levels.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 115 Hydrodynamic The movement or mixing of water as a result of forces such as wind stress at the water surface. Infauna Animals that live within the sediments of the sea floor. Invertebrate Collective term for all animals which do not have a backbone or spinal column. Light attenuation Light reduction (usually refers to a decrease in available light, which occurs with increasing depth of water). Macroalgae Large algae; seaweed. Mean Sea Level The average height of the higher waters over a 19-year period. For shorter observation periods, corrections are applied to eliminate known variations and reduce the results to the equivalent of a 19-year value. Median A statistical measure equivalent to the middle measurement in an ordered set of data (there are as many observations larger than the median as there are smaller). Microphytobenthos (MPB) Microscopic algae that live on or in sediments. Molluscs Soft-bodied animals usually partly or wholly enclosed within a calcium carbonate shell (eg. shellfish). Neap tides Sets of moderate tides, which recur every two weeks and alternate with spring tides. Nutrients Elements or compounds essential for organic growth and development such as nitrogen and phosphorus. Nutrient load The quantity in tonnes per annum of nutrients released into the marine environment. Percentile A measure that divides a group of ordered data into hundredths by quantities. Periphyton Mucous-like layer of microalgae, algal propagules, bacteria, microfauna and particulate matter commonly found coating seagrass leaves. Phytoplankton Microscopic algae that float in the water column. Pollution Introduction of physical, chemical or biological substance or properties into the environment to the extent that causes adverse environmental effects. Species composition Number and abundance of different types of species in a habitat. Species richness Number of different types of species in a habitat. Spring tides Extreme high and low tides which alternate with neap tides and recur every two weeks. Stratification Layering (vertical or horizontal) in a water property such as salinity or temperature. Suspended solids Any solid substance present in water in an undissolved state. Terrestrial Of the land. Topography Detailed description of a land or sea surface represented for example on a map. Trophic Energy level in a food chain. Turbidity Measure of the clarity of a water body.

116 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 10. ABBREVIATIONS

AMSA Australian Maritime Safety Authority ANZECC Australian and New Zealand Environment and Conservation Council ARMCANZ Agriculture and Resource Management Council of Australian and New Zealand CCI Chamber of Commerce and Industry CD Chart Datum (datum for hydrographic surveys: approximately 0.76 m below AHD in Perth coastal waters) CSMC Cockburn Sound Management Council DEP Department of Environmental Protection DCT Department of Commerce and Trade DOT Department of Transport DRD Department of Resources Development EMP Environmental Management Programme EMS Environmental Management System EPA Environmental Protection Authority EPP Environmental Protection Policy EQO Environmental quality objective EQC Environmental quality criteria FPA Fremantle Port Authority IMDGC International Marine Dangerous Goods Code IMO International Maritime Organization KIC Kwinana Industries Council MARPOL 73/78 The International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978, or relating thereto. MfP Ministry for Planning MPB Microphytobenthos NH & MRC National Health and Medical Research Council

NH4 ammonium nitrogen NOx nitrate + nitrite-nitrogen NWQMS National Water Quality Management Strategy pH measure of acidity PCWS Perth Coastal Waters Study RAN Royal Australian Navy SMCWS Southern Metropolitan Coastal Waters Study TBT tributyltin, active ingredient of many anti-fouling paints TN total nitrogen TP total phosphorus TSS total suspended solids WRC Water and Rivers Commission

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 117

APPENDIX A ESTIMATION OF NUTRIENT POOLS AND NUTRIENT TURNOVER IN COCKBURN SOUND

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 119

Appendix A Estimation of nutrient pools and nutrient turnover in Cockburn Sound

In general, the nitrogen in organic matter in sediments is the main ‘pool’ of nitrogen in an aquatic ecosystem, followed by large plants such as seagrasses and algae, and finally, the water column. Since the 1950s, Cockburn Sound and Parmelia Bank has undergone an increase in sediment nitrogen levels in some areas, and a large decrease in seagrass meadows (from 3,900 hectares in the 1950s to 750 hectares today) that have affected the size of nitrogen pools. An approximation of these changes is shown in Table 1.

Table 1 Changes in nitrogen pools in Cockburn Sound

PERIOD NITROGEN POOL (tonnes) SEDIMENTS SEAGRASS SEAGRASS WATER TOTAL * EPIPHYTES 1950'S 8,800 100 20 275 9195 1978 11,000 20 20 550 11590 PRESENT DAY 11,000 20 4 275 11299 present in the top 10 cm.

The above calculations are based on the following assumptions:

• Cockburn Sound area of 92,210,000 m2 and volume of 1,610,000,000 m3; • A water content of 40% and bulk density of 1.245 used for dry sediments; • Average sediment nitrogen content in Cockburn Sound today is 1,560 mg/kg dry weight, and is assumed to be the same in the 1970s; • Average total nitrogen in water in Cockburn Sound today is 170 µg/L (mg/m3); and • Warnbro Sound values were used to approximate Cockburn Sound in the 1950s - 1,250 mg/kg sediment nitrogen, and 170 µg/L (mg/m3) nitrogen in water (i.e. similar to Cockburn Sound today).

Similar approximations can be made for the production of aquatic plants in Cockburn Sound, and the amount of nitrogen used by those plants (Table 2 and 3).

Table 2 Historical changes in estimated plant carbon production in Cockburn Sound

PERIOD PRODUCTION (tonnes carbon/year) SEAGRASS SEAGRASS PHYTOPLANKTON TOTAL EPIPHYTES AND MPB* 1950'S 11,700 3,100 13,800 28,600 1978 2,250 600 25,300 28,150 PRESENT DAY 2,250 600 16,000 18,850 Microphytobenthos, i.e. microscopic algae growing on and in sediments.

Table 3 Historical changes in estimated plant nitrogen turnover in Cockburn Sound

PERIOD NITROGEN TURNOVER (tonnes nitrogen/year) SEAGRASS SEAGRASS PHYTOPLANKTON TOTAL EPIPHYTES AND MPB* 1950'S 470 120 2,120 2,710 1978 90 20 3,840 3,950 PRESENT DAY 90 20 2,790 2,900 Microphytobenthos, i.e. microscopic algae growing on and in sediments.

Note that phyto/MPBs require more N than seagrasses and epiphytes.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 121 The calculations in Tables 2 and 3 involve the following assumptions:

• In healthy seagrass meadows, seagrass production is ~300 g carbon/m2/year and epiphyte production ~80 g carbon/m2/year. Corresponding figures for nitrogen turnover are 12 g N/m2/year and 3 g N/m2/year; • The combined production of phytoplankton and MPBs in the Sound in the 1950s was ~150 g carbon/m2/year, and nitrogen turnover ~23 g N/m2/year; • In 1978, phytoplankton production was enhanced over about half of the Sound – about treble over a third of the Sound and about double over 17% of the Sound; and • Presently, phytoplankton production over about one third of the Sound is about double that of 1950s levels.

The calculations in Tables 2 and 3 are necessarily crude, but do illustrate that the system switched from one co-dominated by seagrass meadows and phytoplankton/MPB to one dominated by phytoplankton/MPB. The amount of nitrogen used by plants also increased greatly, as plants that need more nitrogen (phytoplankton/MPB) were favoured by nitrogen inputs in the 1970s. Tables 2 and 3 also indicate that total plant production in present day conditions is actually less than in the 1950s, but phytoplankton/MPB production and nitrogen use is still higher than in the 1950s.

122 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE APPENDIX B ESTIMATION OF NUTRIENT AND CONTAMINANT INPUTS INTO COCKBURN SOUND

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 123

Appendix B Estimation of nutrient and contaminant inputs into Cockburn Sound Contaminant loads to Cockburn Sound that occur via groundwater and licensed discharges have been estimated based on data provided by industry located within the catchment. This work updates that of Hine (1998, unpublished), and uses the same methodology as Appleyard (1994) to estimate groundwater fluxes to the Sound. Information on licensed discharges, groundwater discharges, and the methods used to calculate loads discharged in groundwater are presented below.

Licensed discharges

Licensed discharges into Cockburn Sound

CONTAMINANT AMOUNT DISCHARGED (kg/year) BP Wesfarmers Kwinana Tiwest Joint Millenium TOTAL Refinery CSBP Power Venture Chemicals Station* Flow volume 440 ML/day 17.76 ML/day Up to 1,600 4.95 ML/day 14 ML/day - ML/day Ammonium- 1,659 3,000 1,200 5,859 nitrogen Nitrate-nitrogen 7,414 6,000 13,414 Total nitrogen 12,039 28,571 9,000 3,900 1,200 54,710 Total phosphorus 2,734 3,837 200 6,771 Total suspended 53,660 52,000 94 105,754 solids Total dissolved 101,469 101,469 solids Fluoride 6,180 6,180 Sulphide 50 50 Aluminium 191 12 2,400 2,603 Arsenic 27 7 34 Cadmium 20 16 36 Chromium 1 1 Copper 20 20 360 200 600 Lead 0 16 0.3 16.3 Mercury 2 2 Nickel 10 69 79 Vanadium 0 13 300 313 Titanium 300 300 Zinc 500 397 100 80 1,077 Oil 2,747 1,800 4,547 Phenol 270 270 * Western Power discharge values are derived from net inputs of a variety of chemicals and products used at the facility, and not actual monitoring of the cooling water discharge.

Groundwater discharges The Cockburn Sound catchment includes a variety of landuses that may impact upon groundwater quality. This study has focussed on the industrial strip that fringes Cockburn Sound and has not attempted to identify every source of groundwater impact throughout the catchment. Generic data are available for regional impacts on groundwater by various land uses and this has been incorporated where appropriate. Groundwater data from 16 sites around the Sound have been reviewed to update groundwater contaminant discharges to the Sound. Most of the monitoring is undertaken under DEP or WRC license conditions, although the scope of groundwater monitoring and management programs at several facilities is well beyond the licence requirements. Monitoring focuses on the superficial aquifers, including the Safety Bay Sand and the Tamala Limestone. Groundwater Monitoring programs at the sites are summarised in the following table below.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 125 Groundwater Monitoring Summary Groundwater Monitoring Program Licensed Operator Facility Number of Monitoring Bores Compounds of Concern Discharge Tamala Limestone Safety Bay Sand Nutrients Metals Hydrocarbons Inorganics pH/EC BP Refinery Oil Refinery 14 38 ✔✔✔ ✔ ✔✔ (Kwinana)L Wesfarmers Agrochemical 17 50 ✔✔ ✔ ✔✔ CSBP Limited Manufacturing Bauxite Alcoa World Refining and ✔✔✔ ✔ Alumina Tailings Storage WMC Kwinana Nickel 29 73 ✔ Nickel ✔ Resources Refinery Woodman Point 9na✔✔✔ Water WWTP Corporation Cape Peron 00✔✔✔ Discharge Western Power Kwinana Power 015✔✔✔ Corporation Station Agrochemical Nufarm Limited ✔✔✔ ✔ Manufacturing Chlor-alkali Nufarm Coogee 04✔✔✔ Manufacture Tiwest Joint Pigment 437✔✔ ✔ ✔✔ Venture Manufacturing Wesfarmers LPG 0 ✔ LPG Coogee 010✔✔✔ ✔ ✔ Chemicals Millenium 04✔✔✔✔ Chemicals Western Starch 15 na ✔✔ ✔ ✔ Bioproducts Manufacturing ✔ Monitoring undertaken, but full details not listed.

126 COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE In addition to these major industrial sites in the immediate vicinity of the Sound, there are a large number of smaller industrial and commercial facilities that present potential impacts to the superficial aquifer and, in theory, the Sound. In these cases no attempt has been made to quantify these impacts as the data are scarce and the magnitude of the potential impacts is very small in comparison to those presented by the larger facilities.

Methods used to calculate mass of contaminants travelling in groundwater The dominant groundwater flow direction below the study area is towards the coast line, thus in the northern section of the study area near Woodman Point, groundwater flow is westwards. In the southern section of the study area groundwater flow is north to north-westerly. It is acknowledged that the interaction between groundwater and the marine environment is complex and significant variations in groundwater flow direction have been documented in the near coastal zone. However for the purposes of this study is reasonable to assume that the observed regional water table conditions are relevant and that groundwater leaving the sites of interest ultimately discharges into the Sound. Groundwater velocity and through flow were estimated as follows:

Groundwater velocity was estimated from the Darcian equation:

v=ki/n Where:

v= groundwater velocity k = hydraulic conductivity i= hydraulic gradient n= effective porosity

Groundwater throughflow in sectors of the coast was estimated from the Darcian equation:

Q = Tiw Where:

Q = groundwater throughflow occurring beneath the site (m3/d); T = transmissivity of the aquifer formation (the product of the permeability (k) and the saturated thickness (b), in m2/d; i = hydraulic gradient (dimensionless); and w = width of aquifer perpendicular to the direction of groundwater flow in metres.

To estimate the mass of contaminants leaving the sites of interest, the coastline was divided by groundwater flow lines to form zones that could be represented by monitoring programs from the respective facilities (i.e. industries). The width of each zone is the same as the width of each facility perpendicular to the direction of groundwater flow. Groundwater conditions for each zone is therefore characterised by the monitor bores on each facility. The reliability of the groundwater quality data for each zone is dependent on the number of monitor bores at each site. At some facilities such as Wesfarmers CSBP and the BP Refinery, an extensive network of monitor bores is present and these are monitored on a regular basis. Groundwater below other smaller facilities may only be characterised by a few bores, and even at the larger sites, information from the Tamala Limestone is generally limited in comparison to the overlying Safety Bay Sand.

COCKBURN SOUND MANAGEMENT COUNCIL PRESSURE-STATE-RESPONSE 127