Essential Filters for the Quality of our Waterways
What is a wetland?
Wetlands are areas that are covered or saturated with water temporarily or permanently. The water is usually slow moving or still and can be fresh, brackish (slightly salty) or saline (salt water). There are many different types of wetlands, small or large, artificial or natural, inland or by the sea, permanent or seasonal. They are referred to as swamps, bogs, billabongs, ponds, lakes, saltmarshes, mudflats or lagoons. Ecologically, wetlands are transitional zones between the land and deeper aquatic environments.
Wetlands support unique plant and animal communities. Wetland plants such as rushes and mangroves grow in shallow water, while others such as paperbarks, swamp mahogany and she-oaks can tolerate “wet feet” and grow around the fringes of wetlands. Frogs, waterbirds, prawns, fish, crabs and many insects rely on wetlands and saltmarshes.
Why are wetlands important?
Clean, cool, clear water with an abundance of healthy organisms is a foundation of our whole eco-system. Wetlands are important because they:
- Are a natural filter system and “conditioner” for our water
- Trap sediment and decrease nutrients and pollutants from entering major waterways and the Lake
- Supply and store freshwater, and control flooding and erosion
- Have an intrinsic natural beauty
- Protect foreshores from erosion, reducing the action of waves
- Provide refuge for fauna during times of drought
- Support diverse ecosystems, including many plants and animals that only exist in wetlands
- Provide breeding grounds, food and shelter for many species such as fish, crustaceans and birds. Saltmarsh and mangroves are nursery areas for juvenile fish and prawns, which is particularly important as Lake Macquarie is one of the major recreational fisheries in NSW
- Provide habitat for the protection and survival of many threatened and protected species and communities, including protected migratory shorebirds and waders who visit Australian wetlands in the summer months
- Offer educational opportunities to students from primary school to university, and are important for scientific research, as there is still a lot we do not know about wetlands.
Types of wetlands in the Lake Macquarie region
There are more than 50 major natural wetlands in the Lake Macquarie region. Natural
wetlands vary depending on the saltiness of the water.
Saline wetlands adjoin the lake or ocean and contain only saltwater. The main vegetation communities are mangrove and saltmarsh. Examples of these wetlands are Swansea Bridge, Black Neds Bay, Five Islands, Stingaree Point and Galgabba Point.
Freshwater wetlands are filled by creek and groundwater systems and support reed swamp and rushes. They are often surrounded by paperbarks, swamp mahogany and tea-tree. Examples of these wetlands are Jewells Swamp and parts of Belmont Lagoon.
Brackish wetlands can change between salt and fresh water depending on the water flowing into the wetlands. They are usually surrounded by Swamp She-oaks and paperbarks. Examples of this type of wetland are Muddy Lake, Toronto Wetlands and wetlands around Cockle Creek.
Constructed wetlands are designed primarily for improving the quality of stormwater runoff. By filtering stormwater, wetlands can help reduce pollutants entering Lake Macquarie and other waterways. Constructed wetlands mimic natural systems and work by slowing the water flow using plants and other structures. The plants trap pollutants, and microorganisms assist to process them as sediment settles to the bottom. Council has constructed a number of wetlands throughout the City including Croudace Bay, Warners Bay, Toronto, Booragul and Glendale.
What are the threats to wetlands?
Wetlands are among the most threatened ecosystems. Since European settlement over 90% of wetland vegetation in the Lake Macquarie LGA has been cleared. Between 1983 and 2004 there was an estimated 34% loss of wetland areas.
Development reduces and degrades wetland habitats, through draining, clearing, grazing, filling, and polluting. Current threats to wetlands in the Lake Macquarie region are;
- Clearing and development of catchment lands which results in greater volumes and more rapid runoff into wetlands.
- Wetland ecosystems and vegetation communities find it difficult to adjust to such rapid fluctuation in water levels.
- Catchment development resulting in accelerated soil erosion with increased sediment loads deposited into wetlands,
- making them shallower and smothering wetland vegetation. Such decreases in the depth of wetlands can change their natural ecosystem due to increases in water temperature and light penetration.
- Pollutants such as oils, greases, and sediments from roads and driveways; excess nutrients from septic tanks; pesticides, fertilisers, and herbicides applied to the land; and toxic chemicals from industry may be transported to wetlands. This can alter the natural water chemistry stimulating growth of unwanted plants or poisoning sensitive wetland plants or animals. Many species need clean water to live. Frogs, for example, are particularly sensitive to pollutants.
- Disturbance in urban areas may disrupt or force wildlife out of wetlands. Factors include increased noise and light levels, habitat degradation and isolation, changes in water quality, increased pedestrian or vehicular traffic, and feral or domestic animals.
- Loss of native vegetation due to competition from weeds such as Alligator weed, Arum lily, Pampas grass and Salvinia.
- Encroachment from adjacent urban and rural land-uses into wetlands through mowing and clearing, dumping of garden refuse and lawn clippings, and use of chemicals on gardens and crops. These all decrease the extent and health of wetlands.
How are wetlands protected?
Wetlands are an important part of the environment and the economy. A number of different laws and policies ensure that they are protected now and in the future.
- State Environmental Planning Policy No.14 (SEPP14 – Coastal Wetlands) requires that development consent be obtained from council before undertaking any filling, draining, or clearing in mapped wetlands. Thirty-six wetlands in the Lake Macquarie region are protected under SEPP14.
- State Environmental Planning Policy No. 71 (SEPP 71- Coastal Protection ) requires approval from the Minister or Council for development within 100 metres of sensitive coastal wetlands.
- Under the Threatened Species Conservation Act 1995 the ecological communities “Sydney Freshwater Wetlands”, “Swamp Oak Floodplain Forest”, “Freshwater Wetlands on Coastal Floodplains”, “Swamp Sclerophyll Forest on Coastal Floodplain” and “Coastal Saltmarsh” are listed as endangered. All of these ecological communities are present in Lake Macquarie wetland areas.
- Local Council policies and planning instruments strictly regulate development in valued wetland areas.
- The Native Vegetation Act prevents clearing of any native vegetation outside residential areas except under particular conditions.
- The Fisheries Act protects mangroves and other marine vegetation, and prohibits their removal or damage without approval.
- The Coastal Protection Act imposes strict development requirements in all development within 1km of the coast or a tidal waterway, which includes Lake Macquarie and the tidal areas of tributaries such as Dora Creek and Cockle Creek.
How can you help?
There are many different ways you can help to improve wetland areas in Lake Macquarie;
- Join a Landcare group that is rehabilitating wetlands in the Lake Macquarie area
- Prevent domestic and farm animals from entering wetland areas
- Learn about wetlands in your area, become informed and have a say about development applications near wetlands or within wetland catchments
- Refrain from walking or driving through wetland areas other than on designated walkways and roads
- Sweep up leaves and grass clippings and compost them, instead of hosing driveways and gutters – green or organic waste in waterways adds nutrients reduces oxygen and spreads weeds
- Wash your car on the lawn or at a car wash that re-cycles its water
- Use fertilisers and herbicides sparingly and carefully so that nutrients and chemicals do not enter waterways
- Put rubbish and pet droppings in the bin so that they, and the nutrients they produce, do not end up in our wetlands
- Install a rainwater tank to reduce stormwater runoff into our wetlands
- Ensure that land-uses on urban and rural properties adjacent to wetlands are not extended through the mowing of native grasses and rushes and other wetland vegetation.