BOAMBEE HEAD OUTFALL

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Monitoring Results

# Indicator Bacteria

Monitoring of faecal coliform bacteria indicated that the primary contact recreation criteria are in most cases met prior to discharge.

# Biological Communities

Smith and Simpson 1996

Found that sewage effluent:

- increased the abundance of tubeworms (Galeolaria caespitosa) with a decreasing abundance away from the outlet.

- increased the Ulva abundance at all three Boambee Head sites compared to reference sites

- decreased species richness at Boambee Head 20 m site which was dominated by the pink alga Corallina berteri.

- decreased the density of the bivalve Lasaea australis compared to reference sites.

- increased the suspension feeders within the kelp holdfast community.

- increased the concentration of lead in liver tissues compared to other locations.

Other findings not related to outfall:

- low concentrations of dieldrin were found in two fish.

Methods:

Smith and Simpson undertook photographic quadrats of the intertidal zone; algal species richness; density of the bivalve Lasaea; kelp holdfast fauna and contaminants in fish. Intertidal sites were at distances of 20, 30 and 60 m from the outlet, with subtidal sites located at 70, 120 and 170 m from the outlet. Intertidal sites were also sampled in similar habitats at Green Bluff and Red Rock (north of Arrawarra Point).

Smith and Simpson also collected six red morwong (Cheilodactylus fuscus) from within 250 m of the outlet and analysed them for heavy metals and organochlorines.

CEE Northern Australia (1999a)

Found:

- significant spatial changes in community structure at all sites, with some of these changes consistent with an impact from the effluent.

- magnitude of impacts were greatest near the outlets at Boambee Head and Corambirra Point with a predominance of coralline algal turf and the green alga Ulva.

- detectable impact extent at each outfall was suggested to be 185 m (Boambee Head), 550 m (Corambirra Point) and 140 m (Flat Top Rock).

Methods:

Intertidal fauna were sampled at close spatial intervals along the shore at each of the discharge sites Corambirra Point, Boambee Head and Flat Top Rock (the latter site being the outlet point of Willis Creek, which receives secondary and some tertiary treated sewage discharge from Woolgoolga STP).

Outfall Site

Faecal Coliform

Red Morwong

Banacles

Ulva

Mollusc

Boambee

(Boam_7) Last updated May 2000