Estuaries & coastal waters

The state's estuaries and coastal waters support important ecosystems, including seagrass, macroalgal reef habitats, fish, invertebrates and many species of marine mammals such as dolphins and seals. These waters provide habitat, nursery and harvest areas for commercially significant fish and crustaceans. Marine aquaculture continues to increase around the Eyre Peninsula and in the South East. Coastal beaches provide swimming, recreational fishing and surfing opportunities across much of the state and are very important for tourism.

What are the problems confronting estuaries and coastal waters?

Water quality in coastal and estuarine areas is greatly affected by how the surrounding area is used. Major land uses in coastal catchments that affect estuaries and coastal waters include pastoralism, cropping, horticulture, aquaculture, forestry and urban areas. Additionally, wastewater treatment plants, and sewage treatment and effluent disposal systems discharge significant quantities of nutrients and organic matter into estuaries and coastal waters.

Stormwater and wastewater from coastal towns have increased the amount of nutrients, heavy metals, organic matter and microbiological loads discharged into estuaries and coastal waters.

These pressures have significantly influenced several of the state's estuaries and coastal waters. The breakdown of organic matter in the Inman River Estuary sediments and nutrient processing cause high levels of ammonia in the estuary (over 40 mg/L), which is toxic to numerous species, particularly fish and can cause algal blooms. The Onkaparinga and Cygnet estuaries also receive excessive amounts of nutrients and organic matter.

Seagrass losses in Nepean Bay and Boston Bay are probably due to elevated nutrient levels. Seagrass and mangrove losses in the Spencer Gulf coastal waters have been attributed to a combination of nutrient enrichment, industrial pollution and climatic conditions. It is also likely that at least some of the seagrass loss in Rivoli Bay (in the South East) is attributable to discharges of agricultural drainage water from Lake George.

What is being done to reduce the impacts in estuaries and coastal waters?

Efforts to reduce the effects of land-based activities on estuarine and coastal waters have been through management of coastal catchments and industries. Coastal water quality management is a multi-agency approach that involves the EPA, NRM Boards, Primary Industries and Resources SA, local government and Department of Environment, Water and Natural Resources.

The EPA's strategies include:

• development of codes of practice and guidelines linked to the Environment Protection (Water Quality) Policy 2015
• audits of industries including dairy and landfills
• input into changes of development policy
• management of licensed industries
• risk assessment of endocrine disrupting chemicals

Initiatives by other government agencies including partnerships with the EPA:

• joint state government and community reef health assessment project
• a marine planning strategy
• the State Estuaries Policy
• Coastal Protection Board
• the Living Coast Strategy
• implementation of catchment water management plans, incorporating policies, strategies, education programs and onground actions to reduce pollutants.

Water quality monitoring

The EPA monitors the following coastal and estuarine waters:

• Nepean Bay
• Boston Bay
• Inman River Estuary
• Onkaparinga River Estuary
• Cygnet River Estuary
• Coffin Bay
• Venus Bay
• Port waterways

>> Aquatic ecosystem monitoring, evaluation and reporting

Further information

• Ambient water quality of Boston and Proper Bays, Port Lincoln 1997–2008
• Ambient water quality monitoring of the Gulf St Vincent metropolitan bathing waters February 1995 - December 1996, Report 1
• Ambient water quality monitoring of the Gulf St Vincent metropolitan coastal waters 1995 – 2002, Report 2
• Ambient water quality monitoring of Lake Alexandrina and Lake Albert
• Ambient water quality of Nepean Bay, Kangaroo Island: Report No. 1: 1999-2004
• Ambient water quality monitoring of the Port River estuary 1995–96
• Ambient water quality monitoring of the Port River estuary 1995–2000
• Ambient water quality monitoring of the River Murray 1990–99 Report No. 1
• Ambient water quality monitoring of the South Australia's rivers and streams (chemical and physical quality) Report No. 1
• Natural Resource Management Boards