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State of the Marine Environment Report for Australia: State and Territory Issues - Technical Annex 3

Edited by Leon P. Zann and David Sutton
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1996)
ISBN 0 642 23012 9


Issues in the New South Wales Marine Environment

Robin Macdonald
Australian Defence Industries Limited
(Formerly of the Environment Protection Authority New South Wales)

Introduction

History

European settlement of the New South Wales (NSW) coastline commenced in 1788 when Captain Arthur Phillip established the penal colony of Sydney. He was conscious of the need for planning to prevent pollution and issued orders to control domestic animals and the indiscriminate clearing of trees near the Tank Stream, which served as the colony's water supply. Despite his efforts, by 1795 pollution of the stream had worsened due to people building too close to, and taking water direct from, the stream and raising pigs behind their homes. By 1810 tanneries, dyeing works, breweries, distilleries and slaughterhouses had also been built around the stream further increasing pollution problems. Expansion of the colony to the Parramatta area was accompanied by clearing of mangroves, clearing of bush for agricultural purposes, infilling of bays, expansion of urban areas and new industries, all of which contributed to pollution of the upper stretches of the Parramatta River. (Similar activities and effects had already occurred in the Sydney area). The necessity for a safe water supply for the settlers and a reduction in the pollution of local waterways finally led to the commencement of sewerage and water supply schemes in the latter part of the 19th century.

European settlement along the coastline progressively occurred to take advantage of abundant timber and coal resources and the productive farmlands along the many river valleys. The largest population centres outside Sydney developed at Newcastle (Hunter region) and Wollongong (Illawarra region) because of suitable port sites and abundant coal resources, both of which facilitated the establishment of iron, steel and associated industries. Expansion of the settlements and development till present times has led to progressive losses of habitat.

On the basis of population growth and building approvals, Department of Planning data have shown that the Hunter and Illawarra regions were amongst the top ten growth centres in Australia in the period 1971-1991. Gosford-Wyong (between Sydney and the Hunter regions) was also in the top ten together with the Richmond-Tweed region (located in the northern portion of the State). Neither of these regions is highly industrialised; both appear to be chosen as desirable regions to live in because of perceived better lifestyles. Nevertheless, this growth is bringing with it the earlier problems of the colony, namely rapid changes in land use and increased needs for water supplies and sewerage services.

More than 80% of the State's population now live in the coastal area with the bulk of the population and industry being concentrated in the Newcastle/Sydney/Wollongong area (these and other locations mentioned in the text are shown in Figure 1). Thus, it is not surprising that the largest pollution problems, and those attracting the most media attention, have been associated with this region.

The major coastal marine issues over the past 10 years have been associated with sewage and its disposal, in particular eutrophication of the Hawkesbury/Nepean River system (the catchment where the bulk of the growth in Sydney's population is occurring) and pollution of Sydney's beaches, adjacent coastal waters and associated fauna (in particular fish). Sewage effluent disposal has been a sensitive issue along the coast, with many communities concerned to avoid disposal strategies which they perceive could lead to similar problems to those identified in Sydney. Coastal development has been controversial and has been discussed at a number of inquiries (see later section).

Coastal waters (estuarine and marine) are extensively used for recreational purposes (swimming, diving, surfing, sailing, boating, fishing) as well as for commerce (shipping and fisheries, including oyster cultivation). Recreational activities in particular have increased over the years as a result of increased leisure time, greater access to transport to coastal areas and waterways, a desire for water (particularly coastal) based holidays, greater ownership of watercraft and an increasing aged (retired) but active group in the coastal community.

Figure 1: State map showing localities mentioned in the text.

New South Wales Coastline

There are competitive pressures between commercial and recreational fishers; the fisheries resource in many species and areas is unable to satisfy the needs of an increasing number of amateur fishers and an increasingly efficient commercial fleet.

The bulk of the State's exports and imports are handled through port facilities at Sydney, Newcastle and Wollongong. Port development in the northern section of Botany Bay (Sydney) has caused concern to environmentalists because of beach erosion and changes in seagrass distribution due to the changed wave energy distribution that occurred during and after dredging. The current extension of Kingsford Smith airport runway into Botany Bay (the third runway) is an incremental development changing the nature of the bay; it will result in removal of seagrass habitat during the dredging and reclamation activities. (However the Federal Airports Corporation is proposing to re-establish some seagrass beds as partial compensation). Other developments, affecting habitats and thus marine communities, are occurring at a smaller (but cumulative) scale in many coastal areas as a result of activities such as the construction of marinas, residents cutting down mangroves or reeds to gain views or access for their boats, infilling (or reclamation) for construction or spoil disposal purposes and extractive industries (to obtain sand and gravel). Although any development by itself may have little effect, the long-term effect of many such incremental changes may be detrimental.

Coastal water characteristics

For the purposes of this chapter, the marine environment has been interpreted as including estuaries and coastal lakes. Such waters are often tidal, which may help flush pollutants or diluted effluents to the ocean where dilutions are greater.

NSW coastal waters are affected by interactions between the southward flowing East Australian Current (EAC) and cooler Tasman Sea water intruding from the south. The EAC is a southerly jet of warm Coral Sea water which may separate from the coast as far south as Ulladulla (400 km south of Sydney) but more typically would separate from the coast at Sugarloaf Point (about 300 km north of Sydney), forming turbulent warm (anticlockwise and often 150 km in diameter) and cold (clockwise and about 30 km in diameter) water eddies. These eddies may affect coastal (shelf) water movements further to the south by encroaching on the shelf as they travel south and dissipate into the surrounding Tasman Sea, a process that can take up to six months. This EAC influence typically causes higher temperatures in shelf waters and a strong flow to the south that is uniform throughout the water column. Recent analysis of offshore current data has shown that the EAC directly influences Sydney's coastal waters about 75% of the time (Lee & Pritchard 1993). In general, the effect of the EAC on shelf waters decreases south of the separation zone whereas strong southern flows and associated warm waters are consistently found further north.

Other influences on coastal water movements are coastally trapped waves, tides and wind. Coastal trapped waves originate in Bass Strait and southern NSW and travel north along the continental shelf past Newcastle with a periodicity of typically 7-20 days. They may cause current reversals and either downwelling (during northward flows) or upwellings (during southward flows) in Sydney inner-shelf coastal waters. Such (natural) upwellings may be associated with increased nutrient concentrations in surface waters which may lead to enhanced algal blooms in coastal waters. The influence of such phenomena is more marked during quiescent periods of EAC activity. Tides tend to have small effects in offshore waters except where ebb jets from bays or large rivers occur. In the Sydney region, winds, particularly those associated with storms from the south-east, may break up thermal stratification in the offshore waters and enable normally submerged sewage plumes to surface.

Northern rivers tend to be broad slow-flowing rivers with well developed coastal flood plains, extensive associated coastal wetlands and coastal towns at the river mouths. High rainfalls in the catchments can lead to high flows and flushing of the estuary and, at times, extensive flooding. Pollution problems have tended to be related to agriculture and agricultural industries, forestry operations, sand mining, urbanisation, flood mitigation works and water supply dams; these have led to concerns about increased erosion and sediment loads, pesticides, nutrients (from sewage, agriculture, piggeries etc.) and changes in flow regimes. Development of drainage channels in some areas has resulted in `acid drainage' problems that have caused massive fish and benthic kills. (Acid drainage results from the oxidation of sulphide minerals in certain soils to acids during dry periods and their subsequent leaching into drains following rain. The acid also dissolves aluminium; both are toxic to aquatic life.) Infilling of wetlands and increased incidence of fish diseases, such as `Red Spot', possibly related to flood mitigation works, have also caused concern.

The catchments of many coastal lagoons (Lake Macquarie, Tuggerah Lakes and Lake Illawarra) are progressively becoming urbanised. Both Lake Macquarie and Tuggerah Lakes are used for cooling of power station generating units. (Lake Illawarra is no longer used for this purpose as a result of rationalisation of electricity generating facilities.) Tidal flushing of all these waters is limited.

Southern rivers tend to be shorter in length and have poorly developed coastal flood plains (with the exception of the Shoalhaven and Bega valleys); often the rivers or lakes may be separated from the ocean by permanent or semisubmerged sandbars. Thus, they have less flushing and are less able to tolerate stresses. Tourism and urbanisation tend to be the major developments although agriculture, fisheries and production and transport of woodchip exports are important local industries. Water quality problems tend to be localised and are associated with nutrient enrichment and erosion and sedimentation.

Major environmental issues and disturbances

Recent inquiries into the coastal zone have addressed planning matters and other environmental issues on both a state and federal basis. A summary of concerns expressed in recent reports is as follows.

The House of Representatives Standing Committee on Environment and the Arts (1991) documented concerns with respect to:

The Resource Assessment Commission (RAC) has published a background paper (1992a) and a draft summary and interim conclusions report (1992b). The latter expresses concerns about the continuing rapid urbanisation of coastal areas and identified likely impacts as:

They felt that the latter would threaten the amenity of many beaches which were considered to be one of Australia's major tourist attractions.

The Parliament of New South Wales Legislative Council's Standing Committee on State Development (1992) has also reported on coastal planning and management in NSW; their recommendations include:

Currently, the Coastal Committee of NSW is carrying out a review of `The New South Wales Coast Government Policy'. This policy is applicable to the coast outside the Newcastle-Sydney-Wollongong region. The Committee has an independent chairman and includes representatives from local government and shires, a delegate from the Nature Conservation Council and government departments.

Some of the above concerns have already been addressed; for example the Australian and New Zealand Environment and Conservation Council (ANZECC 1992) has recently published national water quality guidelines and, together with the Australian Water Resources Council, is working towards national standards for waste discharges. There is a strong commitment to total catchment management (TCM) by the New South Wales Government and TCM committees, involving both government authorities and local representatives, have been formed in many areas. (Under the TCM umbrella, the NSW Government, through the Public Works Department, is developing a State Estuaries Policy). The other environmental issues, which are commonly identified by the community, are reviewed below. Sewage disposal is treated as two segments since ocean or lake/river disposal may lead to different impacts on the environment.

Sewage

Historically, sewerage systems and sewage treatment works have been constructed after urbanisation has occurred. This often led to the installation of inadequate septic disposal systems and resultant illegal disposal of effluents to local waterways. In New South Wales, major construction activities by local authorities in the 1970s and 1980s have resulted in a situation where most coastal urban communities with a population greater than 700 are connected to a sewerage system. Developments in existing or new urban areas are usually connected to sewerage systems before premises are occupied. Thus, the effects of septic systems on waters are not an issue in most areas. Emergency sewer overflows have been installed throughout sewerage systems to ensure that any excess flows in sewers, particularly during and after storms, do not result in sewage overflows in people's homes. Some overflows near urban areas have led to much complaint because of the frequency of overflow and degraded receiving water quality. Illegal connection of storm waters to sewers increases the frequency and extent of such problems. Many authorities are now actively testing areas for such illegal connections; they have been greater than 50% in some older urban areas.

Sewage treatment works effluents in NSW are usually irrigated onto land (including being sprayed on areas such as golf courses) or discharged to local creeks, rivers, lakes or the ocean. The percentage utilised on land has been small to date (less than 5%) and there are several (small) examples of disposal to sand dunes. All discharges have to meet specified licence (i.e. effluent quality) conditions which are set on an annual basis by the Environment Protection Authority (EPA). Licence limits take into account the treatment efficiencies of installed facilities, the type and location of the discharge, possible effects of the effluent on the receiving environment and relevant standards and guideline documents. The effects of effluents discharged to waters can be summarised as follows.

Disposal to ocean

During dry weather, effluent discharges to ocean waters from individual outfalls vary from less than 0.5 to approximately 500 ML/d. With the exception of discharges in the Newcastle-Sydney-Wollongong region, sewage is treated to a secondary standard before discharge from isolated rocky shoreline locations (eg headlands) where dilutions and mixing processes are greater. Environmental monitoring near these latter outfalls has not been extensive and has shown only slight, if any, impacts; there have been few complaints concerning either effluent quality or impacts. (In the Newcastle region all discharges will be to a secondary standard by 1996). Traditionally, sewage sludge disposal from major treatment plants has been mostly to ocean; this no longer occurs in Sydney and will be discontinued in the Hunter region soon. (Higher treatment of sewage results in increasing quantities of sludge to be disposed of; as ocean disposal and incineration are not favoured by the public, disposal strategies will increasingly tend to be to land, as a fertiliser or component of compost, or to landfill).

Public perceptions of the effects of ocean outfalls have been strongly influenced by the impacts observed at Sydney when effluents, which had received only partial primary treatment, were discharged at shoreline sites i.e. prior to September 1990. Then, beaches often had high faecal coliform densities (greater than Health Department guidelines), sewage-derived materials and plastics were often present on beaches (Heggie & Nelson 1992) and some species of fish caught near the shoreline discharges had elevated organochlorine concentrations (Mann & Ajani 1991). Although faecal coliform densities are commonly measured in bathing waters and used as an indicator of the presence or absence of sewage, their densities cannot be directly related to the health risk for swimmers. (It should also be noted that faecal coliforms in receiving waters may also arise from other sources; however their ease of measurement and low cost makes them an extremely useful indicator bacteria).

An Environmental Monitoring Program (EMP) was developed and initiated by the Sydney Water Board (SWB) as a requirement of the State Pollution Control Commission's (SPCC) approvals in the early 1980s to construct three deepwater (60-80 m) outfalls; since 1990 the EMP has been carried out by the EPA. The program measures the environmental changes following diversion of sewage discharges to deep water and includes oceanographic studies (examining and predicting plume behaviour), chemical studies (water quality and contaminants in fish, sediments and moored oysters) and biological studies (fish population and abundance).

EMP studies have shown that since the commissioning of the three deepwater outfalls (August 1991), beach water quality has markedly improved with faecal coliform densities at Sydney's previously dirtiest beaches meeting Health Department guidelines more than 90% of the time in the summer of 1991/92 (Figure 2) as compared with 10% previously. Many of the instances when beaches do not meet criteria occur during or after storms when run-off (including that transported by stormwater drains) and sewer overflows (at coastal locations or to drains) can affect beach water quality. The incidence of sewage-derived grease on beaches has been reduced but not eliminated; its presence appears to be strongly correlated to weather conditions with south-easterly (onshore) winds resulting in a greater occurrence of grease. (Storms often occur during these conditions; these can result in increased sewage flows and bypasses of excess sewage flow to the shoreline outfalls as well as input of pollutants from storm waters.) Progressive installation of finer screens at sewage treatment works has resulted in most large materials (condoms etc.) being removed at the treatment works. Whilst Sydney outfalls carry the largest flows and trade waste component, increasingly stringent controls by the SWB have meant that the pollutant loads carried by these systems are being progressively reduced.

Figure 2:

Figure 2

Disposal to rivers and lakes

Discharges to coastal rivers have undergone secondary treatment, often combined with a tertiary stage for disinfection. Localised eutrophication has occurred when discharges have been to low flow or poorly flushed creeks or rivers. As a result of environmental concerns, extensive studies took place in the late 1970s concerning Georges River and the Hawkesbury/Nepean River system, both rivers occurring in the Sydney region. As a consequence, sewage effluent discharges were diverted from the Georges River to the ocean outfall system to decrease eutrophication and thus improve river water quality.

The Hawkesbury/Nepean River system (to the north and west of Sydney) is more complex and the bulk of the expansion of Sydney's population is occurring in this catchment. The river is used for many purposes ranging from recreation, commercial fishing and as a source of potable and agricultural waters, to receiving and transporting treated effluents and urban and agricultural run-off. Although local sewage treatment works have been expanded to cater for the population growth, there has been increasing concern about river water quality.

The State Pollution Control Commission published two reports concerning this river system (SPCC 1985, 1983a). They concluded that water quality would continue to deteriorate unless ammonia was oxidised at treatment works to a greater extent and total nitrogen and total phosphorus concentrations in effluents were reduced. Since this time, some gains in effluent and river water quality have been made; ammonia and total phosphorus (TP) concentrations in effluents and the river have significantly decreased but total nitrogen (TN) has remained relatively unchanged. This is in agreement with the changes in total nitrogen and phosphorus loads discharged from sewage treatment works above the Colo River confluence between 1979-81 and 1990-91. (TN loads have changed from 1767 to 1868 kg/d whilst TP load have changed from 406 to 151 kg/d.) The result has been that algal growths have decreased but not to target levels in all river sections (less than 20 mg/L chlorophyll a, see Figure 3) (EPA 1992). Further reductions in nutrient concentrations in effluents will be required as catchment populations, and thus nutrient loads from sewage works, continue to increase.

Studies of the major northern rivers were published by the SPCC in the mid 1980s and options for sewage disposal were discussed. Impacts of treated sewage effluent disposal to other coastal rivers have been studied to lesser extents. The rate of installation of phosphorus removal facilities at coastal sewage treatment works has been slow; for some river systems, this may not have large impacts because of the small size of the treatment works, the dilution available or the magnitude of other catchment nutrient sources. However, as populations increase, problems may arise.

Lake Macquarie has traditionally received discharges of treated effluents; however, as a result of an environmental audit (SPCC 1983b) which identified concerns about eutrophication of the northern sections of the lake, it was decided to remove these effluents from the lake by a combination of reuse options and diversion of treated effluents for discharge through an offshore ocean outfall. These strategies should be completed in 1996. Other major coastal lakes do not receive discharges of treated sewage effluents although sewer overflows could possibly impact some areas during wet weather.

Bio-accumulation of contaminants

Large numbers of fish have been analysed as part of the Sydney EMP (Mann & Ajani 1991). This report records that morwong, blue groper and snapper accumulated the highest concentrations of contaminants such as organochlorines and mercury. Red morwong caught near previous cliff-face outfall sites have shown decreased concentrations of organochlorines such as chlordane and dieldrin (Philip 1995) since the deepwater outfalls were commissioned, which is consistent with data showing decreased chlordane levels in oysters moored near such sites (Philip 1995; EPA unpublished data). By contrast, at the deepwater outfall sites, chlordane in moored oysters has only been detected at trace concentrations both before and after the outfalls were commissioned. Chlordane and dieldrin concentrations in rubberlip morwong and snapper have decreased during this period (EPA unpublished data). These preliminary data indicate that the increased dilution of the sewage (now averaging about 500-2000 times) may reduce the availability of such contaminants to fauna. Contaminant concentrations in several fish species caught near Sydney and at more distant control sites since the commissioning of the outfalls will be reported in 1994.

EPA data concerning organochlorines in red morwong caught in both the Sydney and Illawarra areas have shown that the latter contain far lower levels. This is consistent with Water Board (Andrijanic 1991) studies which also found contamination decreasing with increasing distance from Sydney.

Figure 3:

Figure 3

Contaminant data for four species of fish collected by NSW Fisheries in 1991/92 from ten estuaries along the NSW coast have shown that organochlorine concentrations are low in most areas, with highest levels being observed in fish collected from the Parramatta and Georges Rivers (NSW Fisheries pers. comm.).

Fishing closures (or bans) apply at a small number of locations, namely near the three major (old) Sydney shoreline sewage outfall sites, in the upper sections of Parramatta River, Cooks River, Throsby Creek and to the mouth of the Hunter River (Newcastle), South Channel of the Hunter River and Port Kembla Inner Harbour and its tributaries. (Bans at nonoutfall sites have often been gazetted because of concerns about possible contamination arising from effluent discharges or contaminated sediments). The bans around the Sydney outfall sites are under review as more recent data for fish and oysters, showing decreased organochlorine contamination since the deepwater outfalls were commissioned, are becoming available.

Water quality

Water quality has already been covered to some extent in the previous section. However, it is recognised that there are other inputs to waters besides sewage and that alterations to physical features of systems can cause changes in water quality.

As the degree of urbanisation of coastal areas increases, urban run-off impacts may become greater There have been several studies in Australia of the composition of urban run-off, one of which (Rowlands et al. 1992) is of direct relevance to coastal areas. Here, the quality of urban stormwater run-off, under varying flows, from five coastal catchments in the Sydney region was measured and the relationship to local bathing water quality examined. No significant correlation was found between the concentrations of faecal bacteria, nutrients and suspended solids in the drain discharge and in nearby bathing waters during dry weather. Wet weather discharges tended to have equal or higher pollutant concentrations than dry weather flows.

Stormwater run-off from developed rural and urban areas may cause increased rates of erosion and adversely affect waters because the run-off may result in increased rates of erosion and sedimentation and may contain nutrients, oil and grease, trace metals, faecal material (from sewer overflows and pets) and refuse (plastics, cans etc.). There are few documented measurements of the scope of resultant problems; erosion of tributaries, sedimentation of bays and lakes, changing sediment type (sand to mud), together with changes in weed growth and distribution are the problems commonly identified (for example in Lake Illawarra, Lake Macquarie and Tuggerah Lakes). Sediment may smother bottom habitats, decrease water depths or provide a source of fine material which can be readily stirred up by wind waves etc., thus decreasing water clarity and making areas unsuitable for primary recreation (e.g. swimming). As a result of these concerns, increasing attention is being given in new urban developments to the installation of stormwater detention ponds. (Guidelines to improve stormwater quality have been published (SPCC 1989a)). For example, in the Lake Macquarie catchment, developers have been requested to formulate erosion control plans which will be used in conjunction with silt traps, trash racks and floating booms.

Algal blooms, including red tides, commonly occur along the coast, particularly during summer. Their incidence and frequency has not been widely studied. Causes of at least some of these blooms are most likely to be ocean upwellings which bring nutrient rich waters to the surface.

Petroleum spills

Spills of crude oil or refined products have tended to occur frequently but have involved low volumes; thus, in the last two years, 330 spills have been reported to the EPA or Maritime Services Board. The median size of a spill has been less than ten litres and the maximum size 3000 L. The small spills have generally been associated with fuelling of small boats whilst the larger have been associated with pipeline incidents. Most have tended to be of nuisance value rather than of ecological significance, although possible long-term cumulative effects may be significant in some areas. Nevertheless, the large quantity of oil transported and refined in the NSW coastal region has resulted in the precautionary development of oil spill response committees and plans to handle spills of varying magnitude. A series of coastal resource atlases is being produced by the EPA which document environmentally sensitive coastal areas and complement existing manuals and plans for dealing with oil spills. (Funding for this work is provided by the Australian Maritime Safety Authority). (This section does not include the quantities of petroleum products transported to coastal waters by stormwater run-off or arising from road accidents).

Spoil dumping

Sea dumping of dredge spoil regularly occurs although it is generally restricted to those cases where alternative reuse or disposal (of spoil) has been investigated and found to be impractical or exceedingly costly. Spoil is analysed for contaminants before any permission to dump is given. The bulk of the spoil arises from maintenance dredging of Newcastle, Sydney and Port Kembla harbours; this has averaged about one million tonnes per annum over the period 1989-1992. The Sydney harbour tunnel project accounted for approximately half the material dumped during this period.

Habitat losses

Drainage, reclamation, sedimentation, changed energy environment or decreased water quality (due to increased turbidity or eutrophication) are all factors that may result in loss of suitable habitats for fish and other biota, thus raising concerns for the long-term management of marine fisheries resources and ecosystems. Weirs on rivers may restrict and change water flows, thus causing major habitat changes as well as preventing fish migration for breeding purposes. Recent mapping of estuarine wetlands on the NSW north coast has shown that there have been changes over the last 40-50 years (see Table 1, R.J. West, Fisheries Research Institute, NSW, unpubl.). Most habitat categories have declined with the exception of seagrasses in the Macleay River, which have increased in area due to construction of a new river entrance which resulted in a protected tidal inlet being formed. A State Environmental Planning Policy (No. 14 - Coastal Wetlands) was gazetted in 1985; this policy restricts developments of lands and aims to ensure designated wetlands are preserved and protected. (This policy restricts development only to the extent that it makes certain forms of development `designated', and thus requiring the production of an EIS; the Director of the Department of Planning has a concurrence role in any consents). The SPCC (1989b) published an Environment Protection Policy which restricts the use of natural wetlands for effluent disposal purposes. West (pers. comm.) believes that government legislation, such as the Environmental Planning and Assessment Act and the Clean Waters Act together with greater public awareness of the value of wetlands, have helped arrest declines in wetland areas, particularly of mangrove communities.

Table 1: Changes in seagrass, mangrove and saltmarsh areas (km2) in three northern rivers

River Year Seagrass area Mangrove area Saltmarsh area
Tweed River 1947 1.41 2.89 0.70
1962 0.87 2.91 0.38
1981 0.40 3.09 0.20
1986 0.39 2.76 0.20
Clarence River 1942 5.28 5.13 2.41
1966 2.76 5.07 2.34
1971 1.58 5.20 2.41
1981 1.54 4.89 2.14
1986 0.83 4.79 2.05
Macleay River 1956 0.88 5.38 6.09
1976 1.32 5.42 4.17
1981 1.29 5.70 3.97
1986 1.31 5.70 3.97

Data covering the changes in wetland areas for the whole of the State are not readily available, although similar losses have been reported for other coastal lakes and rivers; for example seagrasses decreased by 44% in the Georges River between 1951 and 1979, possibly due to increased turbidity and siltation (Shepherd et al. 1989).

Fish Stocks

Estimates of fish stocks, which are necessary to manage a resource, are difficult to determine. They are often derived from short-term monitoring of stock size and age structure and commercial fish catch data of limited accuracy. For most species, a detailed knowledge of population dynamics, ecology and the effect of environmental stresses is not available. The ESD Working Group on Fisheries (1991) listed species in New South Wales which were regarded as overfished or fully fished; of 41 estuarine and marine species of importance to commercial and recreational interests, there was inadequate knowledge available to satisfy either management or ecologically sustainable development purposes for any of the species. Recreational pressures on some fish stocks in certain areas may be significant and need to be evaluated when management plans for particular species are being formulated. Thus, the potential yield from many fisheries remains uncertain due to lack of information on aspects such as fish stock, fishing effort, catch rates, biology and environmental pollution interactions.

The eastern rock lobster is a documented example (NSW Fisheries 1992) of a species whose NSW catch has fallen dramatically from about 400 tonnes per annum in 1947 to 100 tonnes/annum in 1991. Reductions in some areas of the State have been proportionally greater. During the period 1970 - 1991, the catch per unit effort has declined by two thirds. These two declines led the committee to conclude that rock lobster stocks were unable to sustain the current fishing efforts and that a new management strategy was required. This species is caught in both inshore and offshore waters by both commercial and recreational fishers. Although there is a legal size limit which is attained at approximately 3-4 years of age, maturity and hence breeding does not occur until approximately 6-7 years. The result is that harvesting of immature adults commonly occurs. A management plan has been proposed which includes recommendations that a limit be placed on the number of animals allowed to be taken each year for commercial purposes and proposes protection for large female mature animals. Only time will show whether the management plan will be successful in preventing a continual decline in the resource.

Monitoring of the marine environment

All wastewater discharges to the marine environment are required to meet licence conditions set, on an annual basis, by the EPA. Pollution reduction programs may be required to be developed for progressive implementation where it is believed that the discharge quality needs to be improved. Generally, environmental monitoring is not required to be carried out by the discharger. However, major discharges, such as Sydney's ocean outfalls do have such conditions; these data, together with results being obtained by the EPA from the EMP, are providing an extensive picture of the Sydney marine environment. The data collection phase of most EMP monitoring studies was due to be completed by the end of 1993 and reported in 1994.

In the Newcastle region, the Hunter Water Corporation and the Hunter Port Authority are funding a four year study by the EPA into the presence of contaminants in coastal waters and sediments. As in the Sydney EMP, oysters are being used to monitor contaminant concentrations in the waters. (Initial results have shown that the level of contaminants in the coastal waters are very low). Oysters have also been deployed in the Illawarra region for comparison with Sydney EMP data. Oysters have also been collected from estuaries along the whole coast and contaminant concentrations will be used to indicate the relative status of the different estuaries.

Currently, as part of the Sydney EMP, fish are sampled from the Sydney region, central coast (at Terrigal, 50 km north of Sydney) and at Jervis Bay (140 km south). This sampling was due to be completed in 1993 and decisions will be made as to whether the sampling should continue. NSW Fisheries data for contaminants in four fish species from various estuaries along the coast will complement these data.

The Sydney Water Board is carrying out a variety of marine studies in the Sydney and Illawarra regions in connection with its needs to have information for future planning purposes for its existing shoreline outfalls and stormwater discharges. These studies, when published, will complement other data being collected.

Discussion

Population increases in coastal areas contribute to many coastal problems. Such increases result in augmentation of existing sewage treatment works and/or construction of new facilities. Higher rainfall along the coast tends to reduce the opportunities for reuse of treated effluent and thus effluents are discharged to coastal waters. The location of the sewage discharge sites has tended to cause public concern when coastal locations have been suggested, even though data showing significant adverse impacts (outside the Newcastle-Sydney-Wollongong area) are lacking. The public, in several locations, has preferred discharges to creeks, rivers and wetlands rather than to ocean even though the former routes inevitably result in the same flows reaching the ocean. (This situation has arisen because communities wish to avoid similar problems to those in Sydney before commissioning of the deepwater outfalls.) The result is that a high degree of nutrient removal (to minimise eutrophication of receiving waters) and disinfection (as dilutions of the effluent may be small) are required to minimise impacts. Disposal of effluent to artificial wetlands is often proposed; this has potential but also drawbacks because of land requirements, a lack of long-term experience with such systems and their limited capacity for phosphorus removal.

Increasing urbanisation, together with road construction, farming, flood mitigation and drainage works, may all lead to increased erosion and sedimentation, thus reducing water quality and adversely affecting aquatic habitats. Often coastal urbanisation leads to local pressure for insect control; there is little information on the ecological effects of resultant control programs. The progressive changes in wetlands need assessment and monitoring whilst the importance of different habitat types and the effects of incremental losses are not well understood and require further study. At this stage, contaminant problems have generally been associated with the major urban areas; longer-term monitoring will establish whether the expanding country towns and cities will experience similar problems or whether trade waste controls (on discharges to sewers), controls on usage of chemicals and/or high dilutions of sewage will prevent such problems.

Acid drainage in some northern rivers can decimate all fish and benthic life; although only an intermittent problem in some areas, cooperative research between developers, agriculturalists and fisheries personnel is required to develop management options to prevent such occurrences. The possible relationship of acid drainage to `red spot' disease need to be investigated. Some fish species appear to have declining stocks because of overfishing; a solution to this problem should involve recreational fishers, commercial operators and state and federal authorities.

Whilst there are already some monitoring programs, particularly around Sydney and Newcastle, there is a need to establish longer-term programs on a statewide basis. A better understanding of the influence of oceanic currents along the whole coast and the flushing characteristics of estuaries are prerequisites for effective programs.

The coastal marine environment, which includes associated rivers and tributaries, is sensitive and important and is expected to come under increasing pressures in future years. Its flora and fauna will only be protected for a variety of users if issues and problems are approached on a catchment, and, in many cases, a State basis. This will require cooperation and understanding and a willingness to negotiate solutions which may involve concessions by all parties. For example, sustainable and equitable harvesting of fish by both commercial and recreational interests will require such an approach. Agreed sets of data and guidelines, which can be used by all parties involved in future decision making, will be needed. It is proposed that priority should be give to monitoring the changes in coastal resources (such as wetlands), implementing a coastal monitoring network, evaluating contaminant patterns along the coast, ascertaining fishery stocks and developing guideline documents for nonpoint sources of pollution (e.g. farming, drainage, forestry etc.).

In summary, provision of sewerage services, deepwater outfalls for major Sydney sewage discharges, trade waste controls (by sewerage authorities), nutrient removal and pollution controls are limiting further marine environmental degradation near major urban centres. Sustainable management of fisheries resources and control of diffuse sources are not as well advanced. Further study and monitoring of both water quality and coastal resources, particularly outside the major urban areas, will be required to ensure that the coast and its resources remain available for all to use and enjoy in a sustainable and equitable fashion.

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