Drain L

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Glossary

Introduction

Drain L is one of many drain systems in the South East of the state. It is a fresh to brackish stream that flows in a westerly direction from Lucindale, and discharges into the Southern Ocean at Robe. The catchment is predominantly grazing land. Groundwater is very shallow in this region and the drain is designed to prevent flooding in the area and therefore provide more land for agriculture. Elevated nitrogen (mainly oxidised nitrogen) levels are often high because water soluble fertilisers leach through the soil and get transported to the drain through groundwater flows.

There is very little riparian vegetation at the monitoring site, which is near the Princes Highway, with weeds and exotic grasses predominating. Stream flow for this site is available from the Department of Water, Land and Biodiversity Conservation. Monitoring at this site began in early 2005.

>> Map (3MB 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. 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 June 2006

Habitat	Ecological health
Edge	Moderate
Riffle	Moderate

Drain L usually has a high diversity and generally rates in a good condition. In autumn 2006 both edge and riffle habitats were present but both sites rated as moderate (slightly impaired) due to the absence of any mayflies and caddisflies; the riffle also lacked any simuliids that are normally found in most flowing water habitats throughout South Australia. This could be caused by the unusually low flows that occurred during the first half of 2006.

The edge habitat had a high diversity of 41 different types of macroinvertebrates in June 2006. The most common species were introduced and native hydrobiid snails (Potamopyrgus antipodarum and Angrobia species) and oligochaete worms. The riffle habitat had 29 different macroinvertebrates. Hydrobiid snails, turbellarian flatworms, oligochaetes and nematode roundworms were the most common.

The site had a rich community of molluscs that included bivalves from the family Corbiculidae and two introduced snails (Potamopyrgus and Physa acuta). Several odonates were also present including Diplacodes haematodus, Orthetrum caledonicum, Aeshna brevistyla and Ischnura aurora. The most interesting records were the presence of mites from the family Hydrodromidae and waterbugs normally found in wetlands (Diaprecoris barycephala and Naucoris congrex), which were also found in Drain M.

Download ecological health data

• All the macroinvertebrate data for Drain L (6KB CSV)

Water chemistry

The indicators that are measured in Drain L 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

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

Drain L is similar to Drain M, in being generally fed by groundwater flows that often have elevated nitrogen concentrations. The total nitrogen is probably derived from animal wastes being washed off farms during storms and percolating to groundwater that flows to the drain.

The EPA Mt Gambier Office is collaborating with the South East NRM Board, Primary Industries and Resources SA and The Department of Water, Land and Biodiversity Conservation on a project to enhance our understanding of the relationship between land use and nutrient transport.

>> Archived results

Download water chemistry graphs

• Oxidised nitrogen in Drain L
  
• Total nitrogen in Drain L
  
• Total phosphorus in Drain L
  
• Soluble phosphorus in Drain L
  
• Turbidity in Drain L
  
• Salinity in Drain L

Download raw chemistry data

• All chemistry data for Drain L

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