Cygnet River at Bark Hut Road

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Introduction

The Cygnet River is a brackish stream on Kangaroo Island. It flows east into Nepean Bay, south of Kingscote. Land use in the catchment is a mix of broad-acre cropping and grazing. Elevated turbidity and nutrient levels are the most likely water quality problems. This site at Bark Hut Road is one of two monitoring sites on the Cygnet River (see also Cygnet River at Stokes Bay Road). This is the downstream site and is approximately 25 km from the river mouth. Stream flow and electrical conductivity data for the Cygnet catchment are available from the Department of Water, Land and Biodiversity Conservation at Huxtable Forest and Koala Lodge. >> Map (481KB PDF)

Water quality assessment

Water quality is assessed as being in good, moderate or poor condition by interpreting water chemistry data in the context of protecting environmental values. >> More

Ecological health is assessed in spring and autumn. We use macroinvertebrates for this purpose because they provide a relatively simple way to assess the health of an aquatic ecosystem. >> More

Water chemistry is measured each month (or every 3 months in remote locations). We measure chemical indicators because when they reach a certain level they can cause stress or toxicity to animals and plants in an ecosystem. Some indicators can also indicate if the water is suitable for drinking water or for activities such as swimming. >> More

Ecological health

We collect two samples of macroinvertebrates, one from riffle (or flowing water) habitat and one from edge (still water) habitat. The diversity of the macroinvertebrate community is used to describe ecological health as being in good, moderate or poor condition.

Go here to find out how we classify ecological health in streams.

Ecological health assessment for May 2006

Habitat	Ecological health
Edge	Moderate
Riffle	Poor

The biological assessments of both habitats sampled in autumn 2006 rated below reference condition. This compares to previous years when the site has generally been rated in a good condition.

The edge habitat had 22 different macroinvertebrate species collected. However, only 48 individuals were present in the whole sample. Usually between 200-500 specimens are present in most samples, highlighting the very low number of macroinvertebrates in the edge habitat. The edge habitat was notable by the absence of molluscs, shrimps, dytiscids and hydrophilid beetles, mayflies, stoneflies and leptocerid caddisflies.

In comparison, the riffle had 8 different types of about 8,890 individual macroinvertebrates collected from the whole sample. But the majority of these were small, unidentified hydrobiid snails, an introduced hydrobiid snail called Potamopyrgus antipodarum and oligochaete worms. The riffle included two flow dependent macroinvertebrates (blackfly larvae Simulium ornatipes and predatory caddisfly Cheumatopsyche sp. 2) but lacked crustaceans, chironomids, mayflies, stoneflies and leptocerids.

The salinity of the water was about 3,500 mg/L when sampled, so salt effects may be partly responsible for the poor ecological health classification for the site.

The only unusual finding at the site was the presence of polychaete worms from the family Spionidae, indicating that this lowland stream site may be influenced by estuarine tidal effects on occasion.

Download ecological health data

• All the macroinvertebrate data for the Cygnet River at Bark Hut Road (11KB CSV)

Water chemistry

The indicators that are measured in the Cygnet River at Bark Hut Road are nutrients (nitrogen and phosphorus), turbidity and salinity. The concentrations of these indicators are used to classify the water chemistry as being in good, moderate or poor condition, according to the needs of aquatic ecosystem protection.

Go here to find out how we organise and classify the chemistry data.

Water chemistry classification for April to September 2006

Indicator	Classification
Oxidised Nitrogen	Good
Total Nitrogen	Good
Soluble Phosphorus	Good
Total Phosphorus	Good
Turbidity	Good

The nutrients and turbidity were all classified as good in this sampling period. The grazing and cropping landuses in the Cygnet River catchment can result in nutrients being washed into the river, mainly during winter months; however the unusually dry conditions during this period have probably kept the nutrient concentrations low. The Kangaroo Island NRNM Board has identified important issues that affect water quality in this catchment and the Board is working with landholders to address them.

>> Archived results

Download water chemistry graphs

• Oxidised nitrogen in the Cygnet River at Bark Hut Road
  
• Total nitrogen in the Cygnet River at Bark Hut Road
  
• Total phosphorus in the Cygnet River at Bark Hut Road
  
• Soluble phosphorus in the Cygnet River at Bark Hut Road
  
• Turbidity in the Cygnet River at Bark Hut Road
  
• Salinity in the Cygnet River at Bark Hut Road

Download raw chemistry data

• All chemistry data for the Cygnet River at Bark Hut Road

What is being done to improve the condition of South Australian rivers and streams

Efforts to improve the condition of South Australia's rivers and streams are being driven by various government agencies, primarily

The Environment Protection Authority
The Department of Water, Land and Biodiversity Conservation
Natural Resource Management Boards
Department for Environment and Heritage (SA)

Collaborative projects and programs being run by these agencies are based on the protection of environmental values, as explained in the National Water Quality Management Strategy. >> More

This page was last modified 25-09-2007