As cities spread they turn bare earth into hard, impervious surfaces. Where rains once fell and soaked into the landscape, it now sheets off those hard surfaces, pouring across roads, down drains and into waterways. With this run-off comes contaminants of all types which can create environmental issues.

SA Water recently completed a major upgrade to a storm water project at Noarlunga Downs, south of Adelaide.

The previous old drying lagoons on this site have been decommissioned, much to the joy of the local community. Renewed enthusiasm for the site by the community has seen the Onkaparinga estuary being given a new lease of life

The existing 16 ha site has been converted into a stormwater treatment wetland that doubles as an environmental asset and sanctuary for the birdlife.

The site comprises a series of 9 inter-connected ponds that meande and significantly increase the detention time of stormwater flows (over 30 days) providing greatly enhance filtration of the water and ample opportunity for sediments to settle out before being released into the sensitive estuary environment.

Deep and shallow water depths and islands that provide safe roosting and nesting opportunities for birdlife, dry batters planted with terrestrial shrub land species moving out to some fairly extensive terrestrial buffer zones that have been revegetated to an open woodland habitat.

Planting design emphasis on groundcovers for weed exclusion – Karkala, Ruby Salt Bush, Native Wallaby. The plant density was an important aspect to this project.

With many more species than most wetland projects, this landscape was restored using over 75 local native species and over 205,000 seedlings – replicating the function of natural ecosystems which comprise highly diverse plant assemblages.

Plants grouped into their habitat zones to match the terrain – open water pools, deep and shallow marsh zone, ephemeral edge zones, moving out into dry batters with low shrublands and elevated open woodlands of Sheoak and Mallee Box.

The areas complex design shows the ‘right plant in the right place’ can lead to a thriving and diverse landscape even in demanding environments thanks to the dedicated work of – native plant specialists, wild plant seed collectors and nursery personnel.

SA Water freshwater biologists have sampled the aquatic life in the wetland and have been thrilled to see a thriving community of native fish, tadpoles and glass shrimp thriving in the young wetlands.

There is interpretive trail that joins to up the existing trail along the northern bank of the Onkaparinga River leading up to Perry’s Bend Picnic Area. The trail traverses the high ground to the east and provides some great views across the wetland and bird sanctuary.

Community was keen to recognise the importance of this place and Onkaparinga estuary for the Traditional Owners.

So SA Water has worked closely with contemporary Aboriginal Artist Paul Herzich to commission as number of seats in the form of traditional bark canoes which are imbued with cultural icons that contain important stories of the past the present and future.

A beneficiary of the Noarlunga Downs Wetlands has been the birds. Over 70 different species have been identified, further impressing the sustainable credentials of this region.

If you want the opportunity to see a harmonious eco-system at work, then I’d definitely suggest you visit the Noarlunga Downs Wetlands – River Road, Noarlunga Downs.


About The Author

In the Garden is an exciting new local South Australian TV program on Channel 9 this Summer & next Autumn showcasing the best ‘green’ stories this state has to tell. Check out the latest in garden trends, new plants and top tips to keep those gardens blooming.