Estuaries are semi-enclosed coastal bodies of water where freshwater from streams and rivers mixes with saltwater from the sea. They may be open or only sometimes open to the sea. Because estuaries are places of transition between river environments and marine environments, they are affected by both river currents and tidal flows.
Types of estuaries include bays, lakes, lagoons, harbours, inlets and river mouths.
There are 184 estuaries in New South Wales, including Sydney Harbour, Botany Bay, Port Stephens and Lake Macquarie, and the tidal sections of coastal rivers such as the Clarence, Richmond, Hawkesbury and Tweed.
Why we protect estuaries
Estuaries are unique, biologically diverse ecosystems supporting many different species of plants, animals, birds and fish. They also provide valuable resources for commercial fishing, shipping, tourism and recreation. They are important for environmental and economic reasons and must be managed sustainably.
How we manage estuaries
The health of estuaries can be threatened by coastal development, human activity and natural weather 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 sulphate soils, changes to freshwater and tidal flows, invasive species and climate change.
We work with local councils and other bodies to protect and manage estuaries through:
- monitoring, evaluating and reporting programs
- planning and providing funding to assist local councils through our coastal and estuary grants program
- technical assistance in managing water quality and estuarine conditions.
Key features of estuaries
Estuaries offer critical habitat for many species of animals. They provide vital services for the ecosystems and organisms such as water filtration and habitat protection from the elements.