Groundwater quality is protected in Queensland under the Environmental Protection Act 1994. The intent of the legislation is to maintain the groundwater quality within the range of natural quality variations established through baseline characterisation to ensure that there is no adverse effect on groundwater quality from the operation of any activity.
In Queensland, groundwater conditions are required as part of Environmental Approvals for major activities that potentially affect the groundwater environment. Triggers and limits are often imposed within these conditions to help monitor and protect the groundwater quality. However, there are a range of challenges with the derivation and application of these trigger and limits.
Frequently there is limited baseline water quality data and guidelines or water quality objectives may not be available for the specific location. In the past, guidelines such as for aquatic ecosystems or stock watering have been generically set as limits in Environmental Approvals. However, natural groundwater quality can exceed these water quality guidelines, or conversely, the guideline values may be way above baseline levels. This can result in either false non-compliance or a significant allowance for worsening water quality and potentially environmental harm.
Up-gradient bores have also been adopted in many approvals to provide a comparison with down gradient bores. However, finding appropriate up-gradient bores is frequently not possible as groundwater flow direction is not easily identified. Other complexities include: the choice of monitoring locations; the indicators being measured and the timing and frequency of sampling.
This presentation will look at typical groundwater conditions used in Queensland and some of the potential limitations. Examples of new approaches being implemented to improve the management and protection the groundwater quality in Queensland will be discussed. This will include the use of site-specific values where no default values are available or when groundwater contains naturally occurring concentrations that exceed guideline values.