Scientific Audit of Marine Parks – Background
information for Land Based Impacts Assessment:
Point source pollution
This document and the material referenced herein relate to the Scientific Audit
Terms of Reference:
“Review the degree to which all threats to the varying types of marine
environments have been properly identified and prioritised. In doing this the
panel will consider the degree to which the marine parks process is anticipated
to address each significant threat”
Office of Environment and Heritage contacts:
Dr Kate Wilson, Executive Director Scientific Services
kate.wilson@environment.nsw.gov.au
tel: 02 9995 5610
mob: 0408 462 063
Dr Klaus Koop, Director Environment and Conservation Science
klaus.koop@environment.nsw.gov.au
tel: 02 9995 5536
mob: 0407 462 398
The NRM Ministerial Council Marine Biodiversity Decline Report (2008) has
categorised threats to marine biodiversity as follows:
Climate change
Resource use
Land based impacts
Marine Biosecurity
Marine Pollution
Fishing (Commercial, recreational, indigenous,
plus illegal, unreported and unregulated
Aquaculture
Dredging and spoil dumping
Mineral, oil, gas exploration and extraction
Shipping
Tourism
Diffuse and point-source pollution
Pests and Disease
Oil spills, marine debris,
This material deals with the threat of “Land based impacts” from point sources which
can be controlled through the Protection of the Environment Operations Act (1997)
which provides authority for OEH/EPA regulatory actions, including licences.
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This paper deals with the threat of “Land Based Impacts” in this case from point
source pollution.
New South Wales discharges the majority of its treated sewage directly to the ocean.
Most ocean outfalls discharge relatively small volumes of secondary treated sewage,
but three Sydney outfalls discharge large quantities of primary treated sewage.
Together ocean outfalls at North Head, Bondi and Malabar account for over 70% of
the total nutrients discharged to NSW marine waters (Krogh, 2000; Pritchard et al.,
2003).
Prior to 1990-91 treated sewage was discharged to the ocean off Sydney via
shoreline outfalls at North Head, Bondi and Malabar resulting in well-documented
impacts on nearshore environments affecting recreational water quality, aquatic
ecosystems, and seafood. These major discharges were an obvious initial target for
pollutant abatement measures to protect marine ecosystems.
Sydney’s deepwater outfalls were commissioned during 1990-91, consisting of a
series of diffuser heads positioned at right angles to the shore 2 to 4 kilometres
offshore in water depths of 60m to 80m. A comprehensive, multi-disciplinary
Environmental Monitoring Program (EMP) concluded that the Sydney Deepwater
Outfalls performed remarkably well in achieving intended dilutions and miniiimising
impact on the marine environment (Pritchard et al., 1996; see also papers in Special
Issue of Marine Pollution Bulletin, Vol 33, 1996).
Subsequently detailed ecological risk assessments of Sydney’s large sewage
discharges to marine waters were undertaken to investigate specific toxicants in
effluent. Ongoing monitoring by Sydney Water under licence has confirmed the
general findings of the initial EMP and failed to detect major impacts; monitoring
includes effluent quantity and quality (including whole effluent toxicity), outfall
performance, and impacts on receiving environments (marine sediment quality and
the abundance and diversity of the organisms living in and on these sediments);
Krogh, 2010; Sydney Water 2008, 2009;
http://www.sydneywater.com.au/annualreport/performance/sustainability/clean_water
ways_si4.html).
The focus of Government agency attention then turned to smaller outfalls up and
down the NSW coastline, and the effects of diffuse pollution emanating from coastal
catchments (see Land Based Impacts: diffuse source pollution documentation). A
study by Krogh (2000) documented each ocean outfall on the NSW coast and
compiled all available information available at the time, including documented effects
on surrounding ecosystems. Overall the study found that effects were relatively minor
and limited to the immediate surroundings of the outfall. In all cases, limits for effluent
quality and volume were set and monitored through licences. Roberts and Scanes
(1999) demonstrated very little effect of discharge from small treatment plants on the
NSW central coast.
Of particular relevance to this audit are studies of a sewage treatment plant and
offshore outfall that was commissioned in the early 1990s at Boulder Bay near the
southern limits of the (now) Port Stephens Great Lakes Marine Park (Roberts et al.
1998, Ajani et al. 1999, Smith et al. 1999, Smith and Suthers 1999). This outfall is
currently the subject of further assessment as part of an augmentation process
(Roberts and Murray 2006).
In 2004 a new outfall and improved sewage treatment was commissioned as part of
the Coffs Harbour Sewage Management Strategy, closing down three previous
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outfalls. The outfall location was moved to avoid discharge to Solitary Islands Marine
Park.
At present there are two licensed pollutant discharges to NSW Marine Parks:
secondary treated effluent is discharged via the offshore outfall at Boulder Bay in
Port Stephens Great Lakes Marine Park at a rate of 0.1 – 0.15 m3/s, serving about
38,000 people; and secondary treated effluent is discharged at Bears Point in the
Batemans Bay Marine Park.
More general threats of eutrophication (nutrient enrichment leading to ‘algal blooms’)
were investigated in the late 1990s through a major study which found that natural
upwelling processes, not sewage effluent or river discharges, were associated with
major visible blooms (Pritchard et al., 2001, 2003).
Recreational water quality on beaches, including in marine parks, is monitored
through the ongoing Beachwatch program
(http://www.environment.nsw.gov.au/beachapp/default.aspx)
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