Adelaide Coastal Waters

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About the catchment

The Adelaide Coastal Waters catchment comprises the Torrens River and Onkaparinga River drainage basins plus the southern part of the Gawler River drainage basin, all of which flow into Gulf St Vincent between Port Gawler in the north to Sellicks Beach in the south.

The Port Waterways are wholly contained within the catchment, which is dominated by the Adelaide metropolitan area and outlying peri-urban areas.

Values to be protected

Adelaide's coastal waterways are areas of major ecological, commercial, cultural and recreational importance. The continued residential and industrial development of the Adelaide region and catchments has placed significant pressure on the quality of water entering the coastal waters.

Water quality issues

Historically, a range of pollutants has been discharged to the waterways, although nutrients (nitrogen and phosphorus) are of most concern, being associated with the loss of seagrass and mangroves. Elevated nutrient levels are causing seasonal growths of macroalgae (sea lettuce) and toxic algal blooms such as 'red tides' (dinoflaggelate blooms).

The Adelaide Coastal Waters Study (ACWS) was initiated in 2001 by the South Australian Environment Protection Authority, in response to concerns about declines in coastal water quality and the loss of over 5000 ha of seagrass along the Adelaide metropolitan coastline. The aim of the study was to develop an understanding of the coastal ecosystem of the Adelaide near-shore coastal environment in order to better manage this area. The findings from the ACWS indicate that nutrient rich inputs from stormwater, sewage treatment plants and industrial discharges are the main causes for loss of seagrass along the Adelaide coastline. However, high levels of suspended solids in the near-shore waters, mainly due to the stormwater flows, are a contributing factor for seagrass loss and are a major cause of concern around poor recreational water quality for some of Adelaide's beaches.

Key water quality improvement projects

Key stakeholders / agencies

  • South Australian Environment Protection Authority
  • SA Water
  • Penrice Soda Products
  • Adelaide and Mount Lofty Ranges Natural Resources Management Board
  • Department for Environment and Heritage South Australia
  • Local Government Association of SA - representing Adelaide metro local governments

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