Common Wetland and Waterways Issues
The Blacktown Local Government Area covers approximately 250 square kilometres only 35 kilometres from Sydney CBD. Within this area, there are 45 suburbs with sections of industrial activity and vacant land. Today, urban growth is a major pressure on land in the Blacktown area. The main land uses in the area are residential (38 per cent), rural non-urban (34 per cent), special areas (13 per cent), open space (7 per cent), industrial (7 per cent) and business (1 per cent).
Growing residential areas and numbers of industries in the Blacktown area can impact on the health of wetlands and waterways. This can occur due to possible increases in the level of erosion (from new building sites), nutrients (from animals and gardening) and rubbish that can be transported by stormwater flows. Growing numbers of industries can also impact on the health of wetlands and waterways if their wastes are not treated to a high standard before being released into wetlands and waterways.
Some common wetland and waterway issues in the Blacktown LGA include:
1.Water pollution
2.Urban salinity
3.Waterweeds and algae
4.Introduced fish
5.Native and feral ducks
1. Water pollution
Water pollution can impact on the number of different species found in a wetland or waterway because it fouls the water. Pollution can come from industrial and urban areas, construction sites or leaks in sewage pipes. Some of this pollution can enter a wetland or waterway by stormwater runoff during rain.
There are three main types of pollution:
i) Litter (eg cigarette butts, cans, paper and plastic bags)
ii) Chemical pollutants (eg detergents, oil, grease and fertilisers).
iii) 'Natural' pollution (eg excess leaves, garden clippings, animal droppings and sediment)
Excess leaves and nutrients (from animal droppings or fertilisers) can enter wetlands and waterways in Blacktown causing pollution. This pollution can lead to deterioration of the wetland or waterway.
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Litter in South Creek |
Oil Spill in Car Park near Woodcroft Lake |
Natural Pollution-dog droppings |
Natural Pollution-leaf litter |
Nutrients in small amounts are needed by plants and animals to grow but in excessive amounts nutrients in a wetland or waterway can 'feed' algae resulting in large algal blooms. Algal blooms can harm animals in a wetland or waterway and also affect the quality of our drinking water, recreational activities and the water supply for farm animals and crops.
Soil erosion from building sites is a major cause of sediment pollution in Blacktown wetlands and waterways. Development sites can loosen soil that can wash into a wetland or waterway. One building block in Blacktown can lose up to four truckloads of sediment after a single storm. This sediment can also contribute to flooding by blocking the flow of water in drains that lead to waterways.
Sediment traps at a building sites stop sediment
before it can enter Wetlands or Waterways
Natural and constructed wetlands are important because of their water cleansing ability. Constructed wetlands are especially designed to treat stormwater and wastewater (eg industrial liquids). Wetlands act like sponges, storing water and slowly releasing it, which slows the water speed, reduces erosion and lowers flood heights.
William Lawson Wetlands Lancelot Street, Prospect.
The trash rack collects stormwater pollution
What can you do?
Bin your rubbish, carry your shopping in reusable bags, pick up your dog's droppings and sweep paved areas instead of hosing them.
2. Urban salinity
Salinity is a problem caused by salt build-up in the soil, groundwater and surface water. Salinity is a problem because it affects farmland and urban areas (eg buildings, roads and bridges). On farmland, salinity will destroy the productivity of the land for many years because it cannot be reversed easily. Salinity can also affect areas kilometres away from where it is first noticed because of how the water flows deep under ground. There are two types of salinity:
Dryland salinity is caused by the removal of deep-rooted plants and trees that would otherwise help to keep the watertable deep underground. When these plants are removed, the watertable rises to the surface of the ground carrying with it natural salts that are found in the soil. These salts are concentrated and can lead to the death of animals and plants and also degrade the land.
Irrigation salinity is the other form of salinity that is caused by the over-watering of crops and gardens. When too much water has been applied to the soil it soaks deep into the ground and starts to fill up the watertable. The watertable then rises to the surface of the ground bringing with it the natural salts that are found in the soils. These salts are concentrated and can lead to the death of animals and plants and also degrade the land.
Urban salinity is salinity (either dryland or irrigation) that affects urban areas such as buildings, roads, pavements, pipes and plants. The cause of salinity in an urban area can be kilometres away in another suburb.
The South Creek and Blacktown Creek Catchments are affected by salinity, which appears to be increasing. Salinity can be identified by:
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*Salty water in the local area *Growth of salt tolerant plants (eg Sea Barley Grass, Swamp Oak, Cumbungi) *Trees with thin canopies *Brown/yellow colours in plants and pastures (known as scalding) *Wet or waterlogged soils *Salt crystals forming on the soil surface *Soil feels 'puffy' to walk on *White salty crust on bricks (usually close to the ground) *Cracked and collapsed pavements, roads and driveways *Sinking and shifting house foundations *Corrosion of pipes and fence posts |
Plant Scalding from Salinity at William Lawson Wetlands, Prospect |
What can you do?
Water your garden only when needed, mulch garden beds to reduce moisture loss and water use, grow plants with low water needs and group plants of similar water usage together
3. Waterweeds and algae
Wetlands and waterways in the Blacktown area are at risk from invasion by unwanted water plants. Waterweeds and algae can affect the number of different native water plant species found in a wetland or waterway by taking over and killing off native species. Waterweeds can cause some problems such as:
o Swimming hazards
o Loss of fishing, boating and sailing areas
o Destruction of native plants and animals
o Destruction of visual landscapes
Common waterweeds that can cause major problems include:
Alligator Weed is a native to South America but was introduced to Australia. It can grow in many environments including dry land, but it is usually found in the water. Alligator weed has long, hollow stems and flowers in the warmer months. This weed is one of Australia's worst weeds and if identified must be removed immediately.
Salvinia is a native of southern Brazil. It is a floating rootless water fern with stems that float below the water. This weed likes to grow in the slow flowing water of lakes, ponds, swamps, marshes and slow moving streams and rivers. It can change natural wetlands and waterways by growing quickly and taking over native species. It is one of the world's most harmful waterweeds and is a major problem in Australia.
Hawkesbury River covered in Salvinia
Water Hyacinth is considered a harmful plant in all states of Australia and is on the top 20 list of Australia's worst weeds. It is a free-floating plant with lilac-blue flowers and can grow between 10 centimetres to 1 metre tall in nutrient rich water. This plant should not be grown in garden ponds. It is a major pest in waterways worldwide and can reduce fish numbers and food for water birds; this plant also provides shelter for mosquitos and other disease spreading organisms.
Weeping Willows in the Blacktown area affect Toongabbie Creek, Lower Darling Mills Creek and locations along Upper Parramatta River. Willows are responsible for bank erosion, loss of native vegetation and channel blockages. Willows also add to the flood risk within a catchment. Weeping willows are declared a harmful weed and must not be sold, grown or distributed.
Blue Green Algae (or Pond Scum) can range in colour from red to olive green and are natural in a water system. Blue Green Algae likes shallow, warm, slow moving or still water. Excess nutrients, dry periods and the destruction of water environments can lead to the fast growth of this algae over large areas (known as algal blooms). Algal blooms can discolour water and can be responsible for foul odour and an unpleasant taste.
Blue Green Algae is harmful because some cells contain poisons that can harm the liver and irritate the skin of animals or humans that drink it or touch it. Pets and farm animals have been known to die by drinking too much water contaminated with Blue Green Algae. Blue Green Algae are also responsible for the poisoning of wild animals such as rodents, fish, pelicans, bats and waterfowl.
Humans who drink the algae contaminated water can experience headache, nausea and muscle weakness. People who have touched this algae (poisonous or not) through water activities can experience skin rashes, swollen lips, irritation of the eyes, ear ache, sore throat, asthma and hayfever symptoms.
Harmful algal blooms also affect the health of wetlands and waterways by using up all the oxygen in the water, which leads to the death of other organisms in the system.
Not all algae are harmful to the environment; in fact some provide benefits to the water environment.
What can you do?
Don't empty fish tank water into wetlands and waterways, report sightings of waterweeds to Council and don't use waterweeds in backyard ponds.
4. Introduced fish
Gambusia (Mosquito Fish) and Carp are two introduced fish species that cause problems in Blacktown wetlands and waterways.
Gambusia are native to eastern and southern USA, but are now found around the world. Gambusia were introduced to Australia to control mosquitos but are not very effective because they eat the insects that feed on mosquito larvae. Gambusia are very aggressive and are known to attack fish twice their size giving them the nickname 'killer guppies'. Gambusia nip at the fins and eyes of native fish and eat their eggs. Whitebait and mudfish species are particularly vulnerable to Gambusia because they live in similar environments.
Carp is a large freshwater fish native to central Asia. Carp is farmed in Europe, Asia and the Middle East but in North America, Canada and Australia they are considered a pest. Carp compete strongly with native and introduced fish species and also water bugs affecting the variety of these organisms in the water. Carp rarely eat fish but can eat fish eggs and larvae and also disturb the breeding sites of other fish species. Carp are found in most of the Murray-Darling Basin including the Hawkesbury River, Shoalhaven River, Richmond River and also in Prospect Reservoir.
What can you do?
Build or maintain ponds or pools in backyard areas as a habitat for frogs and keep native fish in backyard ponds.
5. Native and feral ducks
Humans are responsible for the spread of feral animals in Australia. Feral animals in Australia are domestic animals that have turned wild such as ducks, cats, dogs, pigs, horses and goats. Some feral animals have few predators so populations can grow quickly. Some feral animals kill native species, spread disease, compete for food and shelter and destroy habitats.
Feral Ducks at Woodcroft Lakes
The native and feral duck populations found at many of the wetlands and waterways within the Blacktown area are causing problems with water health and habitat destruction. The large duck populations in the Blacktown area trample water plants in and around the wetlands and waterways (such as William Lawson Wetlands and Woodcroft Lakes), and foul the water with their wastes. Feeding the birds encourages them to return (usually in greater numbers) leading to further habitat destrucution and water pollution.
What can you do?
Don't feed ducks and don't dump unwanted ducks in wetlands.
