What are wetlands?

Wetlands include swamps, marshes, billabongs, lakes, salt marshes, mudflats, mangroves, fens, peat lands or bodies of water whether natural or artificial, permanent or temporary. Water within these areas can be static or flowing, fresh, brackish or saline.

Why are wetlands important?

Wetlands are a vital part of our ecosystem. They absorb pollutants and provide breeding, foraging and protective habitat for animals and plants and reduce the impacts of floods, and coastal or estuarine wetlands can even protect our shores from wave action.

Wetlands are nature’s water purifier. Urban development and horticulture has resulted in the generation of many pollutants. Pesticides and herbicides, fertilisers, ’cleaning‘ chemicals, lubricants, minute dust and smoke particles and many other man-made products are washed into stormwater drains, creeks or rivers and the sea, where they can accumulate to levels which can cause serious biological problems.

Wetlands can help clean pollution from stormwater. That’s why their design and form is very important. Many pollutants naturally attach to particles of sediment or small particles of soil. In wetlands, deep ponds of slow moving water allow heavy particles to fall to the bottom, taking with them some of the pollutants. Wetland plants such as reeds, sedges and floating plants have a sticky biofilm on their roots and stems. Smaller particles and dissolved contaminants are caught in this biofilm and the plants absorb many of the contaminants and utilise nutrients for growth. That’s why wetlands have large areas of closely planted reeds and sedges. Open water areas ensure bacteria in the wetland are killed by the sun's ultraviolet rays.

Wetlands are important in other ways as well. For recreational activities, they form nurseries for fish and other freshwater and marine life and, because of this, they are critical to Australia's commercial and recreational fishing industries. It is also one of the reasons why mosquitoes are not a problem with wetlands, as the large numbers of mosquito predators (ranging from little water beetles through to frogs and fish) help keep mosquito numbers from getting out of control.

In urban areas, constructed wetlands are being provided to help clean stormwater to protect our rivers and oceans. They can also be used to help protect against flooding.

As we have realised just how important water is as a resource in our dry climate, wetlands can also play an important role in capturing stormwater so that it can be used at a later time.

Other important advantages of wetlands are their educational, amenity and passive recreational benefits. Most constructed wetlands are completed with a network of trails, community facilities and interpretive signage. Because they are often located close to urban areas, they are a convenient, local destination to observe and learn about local native plants and animals or to spend some quiet, relaxing time close to nature.

While wetlands are ideal water purifiers, they do not make great reservoirs. Water accumulates in the wetland during periods of rain but will evaporate during the hotter drier months. Therefore, in the summer, when the water is most needed, there is little water available. To overcome this, Managed Aquifer Recharge (MAR) schemes (previously known as Aquifer Storage and Recovery Schemes (ASR)) such as the Acacia Terrace wetland in Aldinga may be used to maximise water storage efficiency. As the wetland becomes inundated with water, the clean water is pumped underground into a natural underground aquifer where it is stored. This stored water can then be pumped back up to the surface where it can then be used for purposes such as irrigation or industry. Other possible sites for managed aquifer recharge are being investigated, but unfortunately not all aquifers are suitable for this purpose.

Wetlands also bear historical significance, with some having high cultural value. In particular, many wetland areas throughout Australia are important to Aboriginal people. Consideration of these historical and cultural relationships is a fundamental part of wetland management.

Wetlands within our region

Whilst there were once many natural wetlands within the area, the only remaining significant natural wetland is the Washpool Lagoon at Sellicks Beach. The council has prepared a management plan for the Washpool Lagoon, in partnership with other state agencies with various levels of responsibility over the site. The Onkaparinga Estuary is also major coastal estuary and wetland area, although it has been significantly affected by the construction of the Mount Bold Reservoir and encroachment of urban settlement. Other small coastal estuaries exist near the coastal outlets of Port Willunga Creek, Inglewood Creek and Pedler Creek. 

Within our region, there are a number of man-made wetland areas, managed by the council, including:

• Frank Smith Park wetland, off Magarey Road, Coromandel Valley
• Acacia Terrace, Aldinga Beach
• Hart Road, Aldinga Beach – to be improved through Water Proofing the South stage 2
• Sellicks Creek, Sellicks Beach 
• River Road, Noarlunga Downs
• East of Commercial Road, adjacent Pedler Creek, Moana
• Pedler Creek Reserve Wetland, Seaford Rise – to be improved through Water Proofing the South stage 2
• West of South Road, Old Noarlunga
• Blewitt Springs Road, McLaren Flat 
• Ernest Crescent, Happy Valley
• Commercial Road, Port Noarlunga South
• Grand Boulevard, Seaford Rise– to be modified through Water Proofing the South stage 2
• Brodie Road wetland, Morphett Vale
• Madeira Drive wetland, Morphett Vale

Through our Water Proofing the South program, in addition to the improvements listed above, wetlands are proposed to be constructed at:

• Saubier Creek, Aberfoyle Park
• Byards Road, Reynella East

There are a number of flood detention basins which also have many features of wetlands. These are located at:

• How Road, Aldinga Beach
• the old railway corridor, Seaford 
• near Perry Road, Noarlunga Downs
• Pridham Boulevard, Aldinga Beach
• Blue Point Way, Aldinga Beach
• Dundee Street, Sellicks Beach
• Morrow Road Sedimentation Ponds

Wetlands play a major part in our water management strategy, Water Futures. The strategy also outlines achievements such as the Water Proofing the South initiative, which seeks to maximise wastewater and stormwater re-use through a number of major projects.

For further information about wetlands, contact Andrew Thomas, Coordinator Water Resources, on (08) 8384 0167.