Sixth Creek

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Archived water quality assessments

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.

Ecological health assessment for December 2005

Habitat	Ecological health
Edge	Good
Riffle	Moderate

Both the edge and riffle habitats are usually rated in good condition. The heavy rainfall in November altered the stream channel at this site, modifying available habitat. This pulse of heavy flow may have led to the reduction in diversity seen in the riffle on this occasion.

Ecological health assessment for May 2005

Habitat	Ecological health
Edge	Good
Riffle	Good

Water chemistry

The indicators that are measured in Sixth Creek 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.

Water chemistry classification for October 2005 to March 2006

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

The oxidised nitrogen classification is poor. The elevated oxidised nitrogen is probably due to fertilisers or animal wastes being washed into the creek during storms. It is possible that elevated oxidised nitrogen could lead to excessive algal growth, particularly during warmer months. The classifications for this sampling period are consistent with previous results (see graphs below). There are several projects and programs being run which are designed to improve water quality in Sixth Creek. These are being coordinated through the EPA's Watershed Protection Office and the Adelaide and Mt Lofty Ranges Natural Resources Management Board.

Water chemistry classification for April to September 2005

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

The amount of nitrogen can be increased by fertilisers or animal wastes being washed off farms during storms or due to effluent outfalls. The poor nitrogen results for the recent samples are consistent with previous results.

This page was last modified 13-09-2007