Onkaparinga Estuary

Water quality links:

Home

What is water quality?

Direct to data

Monitoring program & assessments

Major threats & issues

Legislation & programs

Other resources & initiatives

Publications

Glossary

Introduction

The Onkaparinga Estuary is the interface between the inland fresh water of the Onkaparinga River and the salt water of the ocean. The surrounding land is heavily urbanised and there are numerous stormwater drains entering the estuary. There are also the SA Water sewage sludge lagoons on the shores of the estuary. >> More on estuaries

The Onkaparinga River upstream of estuary is monitored at Noarlunga as well as at Lenswood Creek and Scott Creek.

Water quality assessment

Water quality within the Onkaparinga Estuary is assessed as being in good, moderate or poor condition by interpreting water chemistry and algal (chlorophyll) data, according to the needs of aquatic ecosystem protection. >> More

Water quality classification for April to September 2006

Indicator	Ecosystem
Ammonia	Poor
Oxidised Nitrogen	Good
Total Nitrogen	Good
Soluble Phosphorus	Moderate
Total Phosphorus	Good
Turbidity	Poor
Chlorophyll (a)	Poor
Heavy Metals	Poor

NA = not applicable

The water quality monitoring results for this period were generally consistent with previous seasonal results for this site.

Ammonia and chlorophyll (a) were classified as poor in the Onkaparinga Estuary. This is most likely due to nutrient-rich discharges from the local urban stormwater and flows from the Onkaparinga catchment. There is also evidence that the SA Water sewage sludge lagoons leak ammonia through groundwater into the estuary. Increased nutrients promote algal growth and increase turbidity, particularly excess nutrients can cause algal blooms.

Heavy metals were classified as poor (nickel and cadmium). The source of the elevated heavy metals is most likely general urban runoff (stormwater) washing off roads and galvanised iron roofs into the marine environments during rain events.

>> Archived results

Download water quality graphs

• Ammonia in the Onkaparinga Estuary
  
• Oxidised Nitrogen in the Onkaparinga Estuary
  
• Total Nitrogen in the Onkaparinga Estuary
  
• Total Phosphorus in the Onkaparinga Estuary
  
• Soluble Phosphorus in the Onkaparinga Estuary
  
• Turbidity in the Onkaparinga Estuary
  
• Chlorophyll (a) in the Onkaparinga Estuary
  
• Cadmium in the Onkaparinga Estuary
  
• Copper in the Onkaparinga Estuary
  
• Mercury in the Onkaparinga Estuary
  
• Lead in the Onkaparinga Estuary
  
• Zinc in the Onkaparinga Estuary
• Nickel in the Onkaparinga Estuary

Download water quality data

• Water Quality in the Onkaparinga Estuary Site 1
• Water Quality in the Onkaparinga Estuary Site 2
• Water Quality in the Onkaparinga Estuary Site 3

What is being done to improve the condition of within the Onkaparinga Estuary?

SA Water has made a commitment to decommission the sludge lagoons within the next four years.

The EPA is also working closely with the Adelaide and Mount Lofty Ranges NRM board to help reduce diffuse pollution from entering the estuary and the higher reaches of the Onkaparinga River.

Links

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

This page was last modified 18-12-2007