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. Scientific Audit of NSW Marine Parks: Point source pollution 1 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 Scientific Audit of NSW Marine Parks: Point source pollution 2 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) Scientific Audit of NSW Marine Parks: Point source pollution 3