The Issues

Last updated: 08/04/2009

Water quality in the Adelaide and Mount Lofty Ranges region varies markedly from one area to another – from natural and remote areas at the headwaters of some streams to the highly urbanised areas of metropolitan Adelaide. These variations are due to a variety of factors, both natural and human induced.

Natural influences

In more natural areas, water quality varies with vegetation type and underlying geology. Some of the region’s aquifers, for instance, are highly saline and flow into creeks, such as the upper reaches of the Torrens, Inman and North Para rivers. Water quality also varies with climate, seasons and natural processes such as drought, flooding and bushfire. These natural processes can cause water quality to decline, with their impacts becoming more severe and less predictable as a result of climate change.

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Urban pressures

In urban and rural environments, water quality is closely linked to the surrounding environment, land use and management practices. Key pressures on water quality in the region’s urban areas include stormwater discharges, ‘point source’ pollution from industry and waste water treatment plants, and structures that alter natural water dynamics and introduce new sources of pollution. As a result water quality has diminished in many areas, including our fragile coastal environments.

At the same time, water resources are being managed in a more integrated way to ensure their overall sustainability, with innovative approaches to recycling of treated wastewater and stormwater which involve underground storage. While stormwater is generally treated to acceptable levels prior to injection, this storage has the potential to be an additional point source pollution, potentially placing pressure on the ecological and water supply functions of existing native groundwater.

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Rural pressures

Key pressures on water quality in the region’s rural areas include diffuse source pollution, pollution from septic tanks, and agricultural practices that elevate nutrient and pathogen levels and introduce pesticides and other chemicals. These pressures threaten the values we place on our water resources. In the Mount Lofty Ranges Watershed, the catchment area for Adelaide’s drinking water supplies, sediments, nutrients, and at times, pathogens and pesticides have been introduced into water supply reservoirs, requiring expensive water treatment in order to secure water quality for drinking. Similarly, rural pressures on groundwater in the Willunga Plains have risked the quality of water for drinking and for irrigation of vines and orchards.

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