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Estuaries of NSW

What is an estuary?

Estuaries are places of transition. They are where freshwater draining from our coastal catchments mixes with ocean waters. Broadly speaking, estuaries are semi-enclosed waterbodies with open or intermittently open connections with the ocean.

Estuaries in NSW vary in their shape and size, ranging from large coastal embayments and drowned river valleys, such as Port Stephens and the Hawkesbury River, to coastal lakes, such as Lake Macquarie and Wallis Lake, and smaller intermittently open coastal lakes and lagoons, such as Manly Lagoon and Tabourie Lake. Estuaries also support many different habitat types and species.

Estuaries are one of the most important of the state's natural resources and are some of the most intensively used areas of NSW. Just over 80% of the state's population live in catchments surrounding estuaries.

NSW estuaries are valuable community assets, providing many ecosystem services and are relied on for commercial and cultural activities, tourism and recreation.

The way we use estuaries can affect how they function and their overall condition or health.

Estuaries are subject to pressures from human activities as well as natural events such as storms and floods. Common threats to estuary health include increased nutrients and algal blooms, loss of habitat and biodiversity, contaminants and pollutants, accelerated rates of sedimentation, disturbance of acid sulfate soils, changes to freshwater and tidal flows, invasive species and climate change.

The overall target for managing NSW estuaries is that by 2015 there is an improvement in the condition of estuaries and coastal lake ecosystems (NSW State Plan, 2010). 

Through the Estuary Management Program, the Office of Environment and Heritage (OEH) collects data and provides technical assistance and funding to help improve the health of estuaries.

Information on estuaries in NSW

• The estuaries of NSW and some of their physical characteristics, including tidal surveys that measure tidal characteristics, including tidal flow and velocity, water levels and physical water quality characteristics and hydrographic surveys that measure the depth and bottom configuration of waterbodies.
• On behalf of OEH, Manly Hydraulics Laboratory maintains a network of water level recorders. The location of recorders and water level data for these sites can be obtained through Manly Hydraulics Laboratory.
• OEH scientists have developed a risk assessment tool to help identify and prioritise land use planning decisions to protect and preserve the health of estuaries in NSW. The tool is called the Coastal Eutrophication Risk Assessment Tool or CERAT.
• OEH has mapped the boundaries of estuaries in NSW and their catchments. The spatial data is available from http://mapdata.environment.nsw.gov.au/.
• OEH has mapped tidal and mangrove limits in estuaries, which defines the upstream tidal limits in estuaries (the point that tides do not pass) and the upstream limit of mangroves for the main arm and tributaries of estuaries. See Survey of tidal limits and mangrove limits in NSW estuaries 1996 to 2005 (20060118DNRSurveyTidalMangroveLimits.pdf; 3.5MB).
• OEH monitors and reports on the health of NSW estuaries through the NSW Monitoring, Evaluation and Reporting Program.
• Habitat information and maps showing the distribution of seagrass, mangroves and saltmarsh within NSW estuaries is available from Department of Primary Industries.

Assistance to improve estuary health

• OEH's Estuary Management Program assists local councils and communities to prepare and implement coastal zone management plans. Completed plans (completedplansoct2010.pdf; 45KB) are available from the relevant local council.
• State of the Environment 2012, prepared by the EPA, reports on the status of the main environmental issues facing NSW including the state of NSW estuaries.
• The Saltwater Wetlands Rehabilitation Manual provides guidance on the rehabilitation and management of swamp forests, saltmarsh, mangroves and seagrass.
• Environmentally Friendly Seawalls: A guide to improving the environmental value of seawalls and seawall-lined foreshores in estuaries provides options for improving the environmental value of existing seawalls and creating new seawalls.
• Rowland Reserve foreshore stabilisation case study (120799RRCaseStudy.pdf, 958KB) - find out how Pittwater Council constructed an environmentally friendly seawall to control erosion with help from the Estuary Management Program.
• OzCoasts provides information about Australia's coast, including estuaries. Information includes conceptual models, fact sheets on indicators and management tools.

More Information

Further information may be obtained by contacting the relevant office listed below:

North Coast	(02) 6627 0206
Hunter/Lower North Coast	(02) 4904 2594
Sydney	(02) 9895 6267
South Coast	(02) 4224 4164