As well as providing a significant component of the total water supply needs of Adelaide, the catchments across the Mount Lofty Ranges contain important aquatic environments that support a number of key communities as well as numerous threatened species. These catchments are also important agricultural areas and increasing urbanisation and rural living has facilitated a number of challenges associated with water quality issues. This includes contamination of through blooms of toxic algae, pesticides, water-borne parasites, sediment from erosion of degraded river banks, animal and human faecal contamination and localised heavy metal contamination.
Some of the direct causes of ongoing contamination of waterways include:
- Faulty or leaking septic tank systems;
- Direct access to waterways by livestock, which exacerbates erosion of banks, stirs up sediment and contaminates water with faecal matter;
- Runoff from overgrazed and cropping areas delivers excessive sediment and nutrients in to the waterways1;
- Stormwater runoff can carry pesticides, fertilizers, rubbish, oil, heavy metals from human activities (eg. Cultivation, livestock management (dairies, piggeries), industry (wineries, abattoirs), landfills, waste and recycling depots and rubbish dumping, wastewater treatment plants).
- Deciduous trees leaf drop in autumn containing high nitrogen content;
- Rubbish dumping.
Once certain contaminants reach waterways, the pollutants can impact directly on the health of native fish, animals, insects and plants that rely on those riparian ecosystems. Other contaminants such as nutrients can cause the excessive influx of unwanted plants and algae that impact natural waterways.
1EPA (2000) The State of Health of the Mount Lofty Ranges Catchments from a water quality perspective. Environmental Protection Agency, Adelaide, SA.