Edwardstown and surrounding areas Groundwater Prohibition Area

Stage 1 of the EPA’s review of the Edwardstown GPA started in May 2025 to investigate the extent of groundwater contamination. New groundwater monitoring wells were installed, and new and existing wells were sampled to better understand levels of CHC contamination in groundwater.

This assessment was completed in September 2025 and found that groundwater deeper than the depths prohibited by the GPA is contaminated by TCE, and that contamination extends further to the west than the current GPA boundary.

The Stage 1 assessment report – September 2025 is now available.

Next steps

The EPA will start further assessment in mid-2026 to continue investigating the extent of contamination. This will include a new environmental assessment in Park Holme, to the west of the existing GPA, as well as more drilling and testing in the existing GPA to find how deep the contamination is within the groundwater system.

Information collected in September 2023 from the Melrose Park EPA assessment area, adjacent to the Edwardstown GPA, identified the need for further assessment of deeper groundwater to the west of South Road.

In May 2024, the EPA further investigated groundwater in the South-Eastern Edwardstown assessment area, which is a part of the Edwardstown GPA, to understand whether previously identified CHC contamination is also present in groundwater deeper than the existing GPA.

This assessment found that the deeper groundwater is impacted by CHC contamination, with TCE detected at concentrations above the drinking water guideline at several monitoring wells.

These findings prompted the EPA to begin a review of the boundaries of the GPA, to ensure that it sufficiently protects people from accessing contaminated groundwater.

A map of the existing GPA is available here.

The EPA established a groundwater prohibition area in portions of Edwardstown, South Plympton, Plympton Park, Ascot Park, Park Holme, and Melrose Park. This prohibition on the extraction of groundwater was published in the South Australian Government Gazette on 9 January 2018.

The EPA consulted with the local community to provide information and seek feedback on the proposal before proceeding to establish the GPA.

The EPA implemented a comprehensive community engagement plan from 7 August 2017 to engage with residents, landowners and key stakeholders regarding a proposed groundwater prohibition area in Edwardstown and surrounding areas.

A range of methods were employed to seek feedback about the proposed groundwater prohibition area from individuals and organisations, including Government agencies, environment and community organisations, industry, and local residents and landowners.

The community engagement report summarises the community engagement process, feedback received, queries, and suggestions.

Groundwater (bore water) in this area should not be used for any purpose. Contaminants have been identified within the area, and include perchloroethene (PCE), trichloroethene (TCE) and its degradation products, dichloroethene (DCE) and vinyl chloride (VC). Additional chemicals of concern are heavy metals, cyanide and petroleum hydrocarbons.

Chlorinated hydrocarbons are extremely persistent in the environment and natural degradation is expected to take centuries worldwide. They are denser than water and leach through soil and groundwater. They are volatile, carcinogenic and present a potential risk to human health if groundwater is utilised for drinking, showering, washing, filling swimming pools, watering lawns or irrigation of edible produce. Operating a pump to extract groundwater can also draw contamination towards the extraction point, spreading contamination.

Historical chemical use has resulted in site contamination that affects soils on the source sites, groundwater on the source sites, and groundwater offsite in a west to north-westerly direction.

Poor quality and polluted groundwater can seriously threaten the health and viability of communities, agricultural operations and the environment. The EPA advises that the groundwater in this area is contaminated and should not be used for any purpose. Coming into contact with it can pose a risk to human health.

This is especially the case if you ingest it by drinking it, use it to water your fruit and vegetables, wash your food or cook with it (even if it’s boiled). If it’s used to water the garden or lawns, fill a pool or top up a rainwater tank, it creates the opportunity for dermal exposure to the chemicals of concern with absorption through the skin.

Contaminated groundwater should also never be used to wash down paths or the driveway or even as grey water such as toilet flushing. Preventing the extraction of contaminated groundwater is necessary to protect human health and also to prevent the spread of contamination. Spreading is caused by drawing water towards a property if the groundwater is being extracted from a bore.