After European settlement and widespread land use changes, the river corridor was highly altered – changes were made to drainage channels, wetlands, rivers and streams that fed into the River Torrens / Karrawirra Pari, native vegetation was removed, riverbanks eroded, and the water became polluted.
In response, the River Torrens Recovery Project commenced in 2014, targeting priority sites to improve water quality for both the river and the coast, where it enters the sea.
Through the ongoing commitment of the 8 councils along the linear park, National Parks and Wildlife Service South Australia, the Botanic Gardens State Herbarium, Green Adelaide and the local community, the River Torrens Recovery Project has transformed – and continues to transform – the river for the better.
For years we have worked alongside our partners on a range of activities to revitalise the River Torrens / Karrawirra Pari.
In 2014, we formally launched the Urban River Torrens Recovery Project.
Now, a decade on, the success of this program has seen a transformation of the River Torrens / Karrawirra Pari, the soul of our city. Improvements of the system have seen the re-introduction of southern purple-spotted gudgeon after being absent for decades and mean we are even investigating a bold rewilding project to re-introduce platypus to the River Torrens / Karrawirra Pari.
An effort like this has to be tackled as a team. We work closely with a number of partners to look after the river, including:
Together with these partners, we deliver and support a range of activities to transform the system.
You can help look after the River Torrens / Karrawirra Pari, both when you’re at the river and even from your own home.
In addition to exotic trees, the River Torrens / Karrawirra Pari had been invaded by introduced species, such as soursob (Oxalis pes-capre), castor oil plant (Ricinus communrs), giant reed arundo (Donax) and silver leaf nightshade (Solanum elaeagnifolium). These weed species can reduce available homes and food for the many animals that call the river home, as well as compete with and smother native plants reducing the diversity of plants.
Combatting weeds along the river requires a collaborative approach. Controlling weeds upstream is the key to stopping them from flowing down to sites where work has already been done to control these plants. Success requires regular long-term maintenance, to eradicate where possible.
Through this project a long-term pest management plan was developed and is being implemented with a review and update underway to set future directions. Thanks to the success of the program to date, this review can focus even more on rehabilitation with native species.
Some local native plants that can now be seen along the river thanks to this project include chocolate lily (Arthropodium strictum), sweet apple berry (Billardiera cymosa), blue flax-lily (Dianella revoluta) and ruby salt bush (Enchylaena tomentosa).
Introduced tree species can impact water quality by dropping their leaves into the river during autumn – this is uncommon in Australian native trees. Leaves increase nutrients in the water, decreasing the availability of dissolved oxygen that is needed by aquatic animals. This can result in poor health or even the death of fish and other water creatures. The roots of some exotic tree species also contribute to erosion or instability of riverbanks, trap debris and divert flows.
Removing invasive exotic trees and replacing them with locally indigenous species improves water quality, bank stability and habitat for local wildlife, while also reducing riverbank erosion.
Exotic trees targeted through this project include willow, olive, pepper tree and desert ash. These have been replaced with locally native species such as gold dust wattle (Acacia acinacea).
European carp are an introduced, feral species. They are a bottom feeder, which means they stir up mud on the bottom of the river in search of food, making the river turbid and murky. This is problematic for native fish, irrigation and fishers.
To control European carp, a technique called ‘electrofishing’ has been used in the River Torrens / Karrawirra Pari to remove large volumes of this species. This technique involves temporarily stunning fish and removing carp manually from the river. Native fish are not harmed by this process.