BURWOOD BEACH OUTFALL

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Monitoring Results

Indicator Bacteria

Water quality monitoring of faecal coliform bacteria in receiving waters indicate that levels are within the guidelines for primary contact recreation and protection of human consumers of seafood (MHL769 1997).

Biological Communities

Found that sewage effluent:

• substantially polluted the beach in the vicinity of the shore line outfall

• modified the marine community as far as 2kms away (zooplankton was dominated by filter-feeders).

• dramatically altered the structure of the rocky bottom community to accommodate increased levels of suspended solids – this then allowed filter feeders such as sponges and crinoids to dominate.

• enriched the number of individuals and reduced the species diversity of the soft bottom community at sites nearest the outfall.

• adversely affected the fauna of surrounding sandy beaches, with filter feeders being displaced by deposit feeders.

• enriched fish communities, particularly those that fed on and in the sediments.

General findings (not necessarily related to the outfall):

• recommended the construction of a deepwater ocean outfall.

Methods:

Laurie, Montgomerie & Pettit (1977a) investigated phytoplankton (chlorophyll-a concentrations only - off Boulder Bay, Burwood Beach, Belmont Beach and First Point); zooplankton (off Boulder Bay, Burwood Beach, Belmont Beach and First Point); rocky bottom benthos (First Point, Little Beach Burwood Beach and Boulder Bay); rocky shore ecology (First Point, Little Cove and Little Beach); soft bottom benthos (Belmont Beach, Burwood Beach, Stockton Beach, Dudley Beach, Merewether Beach, McMasters Beach and Avoca Beach); sandy beach fauna (Belmont Beach, Burwood Beach, Dudley Beach, McMasters Beach and Avoca Beach); fish communities (using otter trawls – Burwood Beach, Belmont Beach and McMasters Beach); and contaminants in fish (McMasters Beach and First Point).

Found that sewage effluent:

• directly impacted the structure of benthic rocky bottom communities

• slightly lowered water transparencies

• provided an abundant supply of particulate organic matter which permitted the filter feeding elements of the community to flourish at the expense of the light requiring plants.

Methods:

Laxton and Laxton (1979) investigated the benthic communities living in the discharge areas of Nelson Bay, Wanda Head, Corlette, Boulder Bay and Burwood Beach using photo quadrats (rocky bottoms) and sediment core samples (soft bottoms - Corlette only) between 1975 and 1979 (Boulder Bay and Burwood Beach).

Found that sewage effluent:

• increased the richness of rocky bottom benthos and area occupied at North Reef

• changed the composition of organisms on the horizontal surfaces at South Reef (fluctuations occurred in both algal and sedentary animals).

But found no effect on:

• the vertical surfaces of South Reef with sedentary animals rather than plants being the dominant organisms present.

Methods:

Laxton and Laxton (1982) continued monitoring benthic communities living in the discharge zone of sewage outfalls at Nelson Bay, Wanda Head, Corlette, Boulder Bay and Burwood Beach. They included data from 1975 through to 1982. In addition, they reported on pre-discharge monitoring of proposed outfall sites at Boat Harbour and Birubi Point.

Findings:

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Methods:

The sampling program commenced in January 1985. For the rocky bottom community studies, two areas of low profile rocky reef were selected. One site located in Catherine Hill Bay away from the influence of the outfall was designated as the control area. The other site located in 18m of water on South Reef was designated as the experimental area. Photo-quadrats were used to measure sub-tidal rocky benthic communities and initial sampling frequency was set at once every six months.

Sampling of soft bottom benthos in 18m just off the edge of South Reef was also undertaken. Samples of the sediment were taken using a diver operated device which consisted of an aluminium box (200 X 200 X 100 mm). A control area at Catherine Hill Bay in 14m water depth was also sampled once every 6 months.

Water quality studies were located as close to each outfall as possible and at a location seaward of the outfall (approximately 2km). Control stations, both an inshore and an offshore site, were located at the far northern and far southern ends of the study area (between Port Stephens and Catherine Hill Bay). Laxton and Laxton (1986) is largely a presentation of data for the first two years of the new study design.

Found that the sewage effluent:

• increased the turbidity of offshore waters adjacent to the outfall from surface to bottom

• heavy metal concentrations in sediments collected in July 1990 from Catherine Hill Bay and Burwood Beach were low with no significant differences between control and experimental sites.

Found that the sewage effluent:

• decreased turbidity in water column

• small kelp (Ecklonia radiata) plants appeared on the rocky bottom in 22 m of water.

But found no effect on:

• No outfall effects were noted for the soft bottom benthos.

General Findings (not necessarily related to the outfall):

• elevated concentrations of contaminants were found in fish collected in the Newcastle area.

General findings (not necessarily related to the outfall):

• increased manganese levels in sediments at certain times at the outfall compared to the range of concentrations found in Sydney (may/may not be attributed to the outfall).

• Of the 17 organochlorines tested, only three (technical chlordane, DDE and DDD) were detected in deployed oysters. However, because of the low frequency of detection no impact versus control comparisons could be made. Trace metal concentrations in oysters were within or below the range of concentrations found in oysters deployed offshore of Sydney and naturally occurring in other estuarine areas of NSW. Trace metal concentrations in sediments were comparable to concentrations found in Sydney with the exception of zinc, lead and manganese at an offshore dump site (Spoil Ground) and the entrance to Newcastle Harbour.

• All mean trace level concentrations were below the concentrations considered to have the potential for adverse biological effects (with the exception of manganese levels in three sediment samples – 2 samples from Burwood Beach and 1 sample from the Spoil Ground).

Methods:

Ajani and Wansborough 1996 undertook contaminant bioaccumulation studies (using deployed oysters and sediments) over the period 1992 to 1996.  During the first two years of the Hunter EMP, oysters (Crassostrea commercialis) were deployed at potential contaminant sites (including the outfall sites of Boulder Bay, Burwood Beach and Belmont Beach) and at a number of control sites. Retrieval of oysters occurred twice a year at which time sediment samples were also collected by divers using corers. These samples were analysed for organochlorine and trace metal levels.

Found that sewage effluent:

• had a dilution effect of about 450:1

• caused light transmission reductions although the reduction was within an acceptable range based on ANZECC Guidelines for water-based recreational activities.

• caused significant differences in benthos between Diffuser 9 & 10 and control sites (could not be attributed to the sludge discharge through diffuser no. 10).

• caused sludge deposits on the sand and in reef crevices near the sludge diffuser (No. 10) and occasionally near the closest effluent diffusers (No 8 & 9). Sludge was also detected in two small caves located near the sludge diffuser pipewort. These sludge deposits on the seabed varied with sea conditions.

General findings (not necessarily related to outfall):

• Concentrations of organochlorine compounds in red morwong were found to be low and well below the National Food Authority’s Maximum Residue Limits (EPA unpublished data, HWC 1994).

Methods:

EPA carried out photoquadrats of rocky bottom macrobenthos, contaminants in fish and further studies of local oceanography.  Photoquadrats of rocky bottom macrobenthos were taken at control sites and outfall sites before the discharge of sludge (November 1993) and after the discharge of sludge (April 1994 – EPA unpublished data, HWC 1994).

Ten red morwong (Cheilodactylus fuscus) were collected from near Diffuser 10 (Burwood Beach outfall site) and analysed for organochlorine contaminants.

General Findings (not necessarily related to outfall):

• there may be an effect due to sludge disposal on benthic organisms, but that the response was ambiguous. Natural spatial and temporal variability at the assemblage and individual taxonomic level may be masking the effects due to sludge disposal.

Methods:

TEL continued sampling of benthic flora and fauna on rocky reefs using the same techniques as the previous EPA studies.

Red Morwong

Outfall Site

STP Location

Faecal Coliform

Burwood Beach

(Burw_7) Last updated May 2000