Unfortunately, as the river flows through the metropolitan area, it is fed by stormwater runoff from the surrounding suburbs, as well as contaminants from urban areas, affecting the water quality. These impacts on the water quality caused a decline in native aquatic animals, and exotic trees were affecting the stability of river banks and obstructing flow.
In response to these issues, the River Torrens Recovery Project (now Urban River Torrens Recovery Project) commenced in 2014, targeting priority sites to improve water quality and ecosystem function in the river and the coastal waters where it enters the sea.
Through the ongoing commitment of the eight councils along the linear park, and the former Adelaide and Mount Lofty Ranges NRM Board (now Green Adelaide), the Urban River Torrens Recovery Project has pioneered a successful project of collaborative management that involved the broader community.
Before urbanisation, rainfall largely soaked into the ground, only running into creeks and rivers during heavy falls or when the ground was saturated. Today, rainfall runoff flows quickly across pavements, roads and carparks, taking with it pollutants such as oil, cigarette butts, plastic litter, dust, leaves and dog poo. Polluted stormwater flows directly to the nearest creek without being treated, carrying high levels of nutrients which can cause algal blooms and smother seagrass and reef systems, presenting the most significant threat to water quality in the River Torrens.
Gross pollutant traps and water sensitive urban design structures – such as roadside raingardens – help to improve water quality by capturing leaf-litter, rubbish and sediment before they enter watercourses. Raingardens also help to filter pollutants from water.
Exotic trees impact on the quality of our waterways and the animals that live there. The autumn leaf drop from exotic trees increases nutrients in the water and lowers dissolved oxygen needed by aquatic animals, resulting in poor health and even death of fish and invertebrates. The roots of some exotic tree species can also contribute to a loss of river bed and bank stability, leading to expensive erosion problems.
Removing invasive exotic trees and replacing them with locally indigenous plants improves water quality, bank stability, and the native habitat of Linear Park.
The success of the Urban River Torrens Recovery Project and local community support has seen it extended beyond its initial two years.
