Boddington Bauxite Mine

By Alex Gardner, Emeritus Professor at UWA Law School

Project: Boddington Bauxite (Worsley) Mine, South32,Worsley Alumina Pty Ltd

Location: Boddington, WA

Impact: Water resources and groundwater dependent ecosystem

In 2024, South32 was approved to expand the Boddington Bauxite Mine (the Worsley mine) and increase groundwater abstraction from 500 ML per year to 900 ML per year. Within this expansion area is Newmont’s Boddington gold mine (the Newmont mine); in April 2025 the Minister renewed Newmont’s surface water licence for 15 gigalitres per annum from Hotham River.

The area has been impacted by historical clearing, mining activities, and a drying climate, with low rainfall and low recharge rates. The Worsley mine activities include clearing and groundwater abstraction which presents risks to groundwater dependent ecosystems from increasing salinity, the rise of water tables (groundwater mounding) and drawdown.

The key water body at risk from these mines is the Hotham River, which is critical habitat for the endemic south-western snake necked turtle, a species that is listed as Near Threatened on the IUCN Red List of Threatened Species. Cumulative clearing and removal of deep-rooted native vegetation has led to groundwater mounding and elevated salinity levels at the Hotham River. The salinity levels are now well above Australia and New Zealand Guidelines 2018, leading to death of riparian zone trees and decreased stream biodiversity.

Figure 1: Hotham River and bridge. Image supplied by WA Forest Alliance.

In the company’s environmental assessment of its proposed Worsley mine expansion, there was only limited analysis of risks to groundwater dependent ecosystems and minimal hydrogeological data. There was however an indication that the groundwater may support EPBC-listed species; this should have prompted the EPA to require further investigation from South32.

The EPA’s 2024 assessment was that groundwater drawdown from the Worsley production bores would be localised, and regional cumulative impacts not significant. In December 2024, the WA Minister for the Environment issued Ministerial Statement 1237 approving the Worsley mine expansion under the EP Act.

The Worsley mine is established under a 1973 State Agreement with Worsley/South32, by which the State promises to provide water sufficient for the needs of the mining operations at points chosen by the company within the mineral lease (Alumina Refinery Act, 1973). These State Agreement water rights are implemented under State law and are subject to compliance with any environmental protection requirements imposed by a State agency.

The main legal authority for South32 and Newmont to take water for their mining operations comes under the Mining Act mining leases administered by the Department of Mines, Petroleum and Exploration (Alumina Refinery Act, 1973). Mining lease water rights are subject to the operation of the Rights in Water and Irrigation Act 1914 WA (the RIWI Act). The western part of the Worsley and Newmont mining areas are proclaimed for RIWI Act surface water licensing of extraction from the Hotham River. Newmont Boddington Gold’s Surface Water Licence was renewed for ten years on 9 April 2025. It authorises the taking of 15 gigalitres/year from the Hotham River. South32 was issued a new Surface Water Licence to take 3 ML/year from the Hotham River for the Worsley mine until March 2027, so it is relying mainly on groundwater.

The area of these mines is not proclaimed for groundwater licensing. Outside of their mining leases, South32 and Newmont can also buy groundwater from landholders who have unregulated common law rights to capture and use groundwater. However, the use of groundwater from areas not proclaimed for RIWI Act licensing is subject to regulation under the EP Act. The Minister for Environment, under Ministerial Statement 971 (2014), authorises the Newmont mine to use 47 ML/day (approx. 17,000 ML/year) and requires Newmont to ensure that mine dewatering drawdown does not cause long term adverse impacts to groundwater dependent vegetation, including riparian vegetation of the Hotham River.

Figure 1: Hotham River. Image by Jess Boyce

For the Worsley mine, Ministerial Statement 1237 includes condition B16-1 for the protection of “inland waters” and groundwater dependent ecosystems. It requires proposal outcomes of “no adverse impacts ... attributable to the proposal” to hydrological regimes and water quality of relevant rivers (including Hotham River), “groundwater ecosystems” within the mine area, and “to neighbouring groundwater users”.

The means for achieving these objectives is a Water Management Plan (WMP) which, under Condition C4-1, is required to show that the outcomes are met through monitoring against “threshold criteria” (limits) and “trigger criteria” (warnings) and fulfilling contingency measures if these criteria are not met.

However, the EIA of the South32 expansion proposal did not adequately assess the cumulative impacts on water resources of the two mines operating so closely. In contrast, the scoping of Newmont’s 2025 expansion proposal does clearly require a CIA of Newmont’s mine interacting with other mining operations in the region, including those by South32 and Alcoa (Newmont, 2025). It could be even better if the Minister for Water were to proclaim all the surface and ground water resources of the area for water licensing and make an integrated water allocation plan to guide the water licensing in the area.

Recommendations

Ensure stronger Ministerial Statement conditions by including the threshold and trigger criteria, and the contingency measures.
Better implement the Environmental Impact Assessment of cumulative impacts on water resources.
The Minister for Water should proclaim for licensing all the surface and ground water resources of the area and make an integrated water allocation plan for management of surface and groundwater

(See Recommendations 19 - 22 under Water Reforms: 'Water Planning', 'Implement Office of the Auditor General's Recommendations', 'Ensure Safe Drinking Water').

Citations

Alumina Refinery (Worsley) Agreement Act (WA) (1973). ‘First Schedule, cl.13(1)-(5) meet the water requirements of the refinery and 13(6) for mining operations.’

Newmont (2025). ‘Boddington Mine, Life of Mine Extension Amendment, proposal. Assessment Number 2507, approved scoping document. pp.7 and section 2.3, p.9. EPA WA