FORSTER OUTFALL

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Monitoring Results

Indicator Bacteria

PREDISINFECTION (<1997)

Monitoring of faecal coliform bacteria in the receiving waters indicated that primary contact recreation criteria were considered to be met within 200m of the outlet and the protection of human consumers of seafood guidelines were considered to be satisfied within 600 m of the outlet (MHL769 1997).

POST DISINFECTION (>1997)

Not available

Biological Communities

 

TEL (1993)

 

Found that sewage effluent:

  •  had resulted in localized changes in the intertidal community in an area extending about 20 m either side of the discharge point

  • there had been minor changes in the subtidal habitat macrobenthos and fish community.

But found no effect on:

  •  the abundance of most plants and animals near the effluent discharge

  •  the number of grazers at the outfall.

  •  the patterns of zonation at the discharge point was due mainly to the extension of Ulva into the mid-shore zone and a greater abundance of barnacles in the low-shore zone, rather than to a reduced abundance of grazers or sessile invertebrates

  • no correlation between subtidal habitats and the abundance of macroinvertebrates, or between subtidal habitats and the abundance or species richness of fish.

  • Organochlorine pesticides were not detected in any of the fish from Shark Rock.  

General findings (not necessarily related to outfall):

  • Kelp (Ecklonia radiata) and sea urchins (Centrostephanus rodgersii) were not recorded at Shark Rock (differences in habitat type and structure may have been responsible).

  • Shark Rock had a smaller fish community relative to the reference locations (may be due to differences in habitat type/complexity).

  • All three species of fish tested from all 3 locations had levels of trace metals below NHMRC (equivalent to the NFA standards (Anon 1992) maximum recommended levels (TEL 1993), however there were no trends for greater concentrations of trace metals in fish from Shark Rock.

  •  Rock cale from Latitude Rock (a reference location) had the highest concentrations of copper.

Methods:

Field surveys were undertaken on the rocky shore at Shark Point and two reference locations (a small headland near Latitude Rock and the north-western side of a small island offshore from Sugarloaf Bay at Seal Rocks). Intertidal assemblages of plants and animals were sampled in three zones (upper slope, mid-shore and low-shore); a stationary visual technique was used to estimate the abundance of rocky reef fish; and three individuals of luderick (Girella tricuspidata), rock cale (Crinodus lophodon) and blue groper (Achoerodus viridis) were caught and levels of organochlorine pesticides and trace metals in edible flesh were determined.

 

Outfall Site

Outfall Site

Outfall Site

Ulva

Faecal Coliform

Kelp

Forster

  

(Fost_7) Last updated May 2000