Groundwater quality
Groundwater is vulnerable to contamination from a range of activities, including industry, agriculture and land use changes.
Poor management of groundwater can cause a range of water quality problems.
Cleaning up groundwater can be very difficult and take decades to accomplish. It is also very expensive. For this reason it is better to minimise or avoid activities and practices that may impair groundwater quality.
Groundwater quality can be compromised in a number of ways.
Pollution
Groundwater close to the surface is generally the most at risk of pollution. Groundwater can be contaminated by point sources such as landfills or localised chemical spills, or diffuse sources such as widespread fertiliser use or urban runoff.
Pollutants can include:
- microbiological contaminants from sewage and effluent
- heavy metals
- petroleum fuels
- industrial solvents
- excessive nutrients (e.g. phosphates and nitrogen)
- detergents
- pesticides.
Salinity
Irrigation, inappropriate disposal of wastewaters and land clearing can all increase groundwater salinity. Saline groundwater can be a problem in areas where excessive freshwater is being extracted.
When this occurs in coastal areas, where freshwater coastal sand aquifers are surrounded by saline groundwater linked to the sea, the depleted the freshwater resource is replaced by inflowing sea water.
Impacts of poor groundwater quality
Poor groundwater quality can have significant economic impacts by reducing agricultural and horticultural productivity. Polluted groundwater can cause environmental damage where it discharges into waterways and wetlands, and may have adverse impacts on groundwater-dependent ecosystems. Poor quality groundwater may also pose risks to human health.
Addressing groundwater quality issues
The National Groundwater Assessment Initiative under the Groundwater Action Plan provides for investment in managing risks to groundwater quality.