Monitoring water programs: Cadia Valley Operations

The review included a detailed examination of a range of documents and resources, including:

• annual environmental management reports
• groundwater, surface water, and aquatic ecosystem monitoring reports and associated data
• groundwater model updates
• dam management plans
• tailings storage facility seepage mitigation and management studies
• site water management plans.

As part of this review, Hydrobiology visited Cadia Valley Operations to inspect key monitoring locations and gain direct insight into the operational and environmental context. Findings from this site visit were incorporated into the final report.

The quality, scope, and methodology of the monitoring programs were critically reviewed to determine if they are robust and align with best practices and regulatory requirements. Specific attention was given to identifying gaps or areas for improvement in the identification and reporting of potential impacts. This included statistical analysis of the 10 plus years of data from the monitoring programs to assess potential environmental impacts.

The review found that the monitoring programs have generated large, valuable, long-term datasets. It also identified opportunities to enhance and improve the effectiveness of the programs. Among a range of observations Hydrobiology found that:

• there is no conclusive evidence linking Cadia Valley Operations to significant degradation of waterways, but localised trends, particularly elevated metals in groundwater and sediments, highlight the continued need for assessment of potential cumulative or lagging impacts
• the roles and context of monitoring sites are not clearly defined and there are gaps in the monitoring networks regarding representation of key zones and appropriate control and reference sites
• limited integration of flow data in the surface water monitoring program restricts the ability to quantify contaminant loads and potential fluxes
• the lack of formal trend or statistical analysis reduces the ability to detect gradual changes or patterns over time
• limited integration between water quality and ecological monitoring outcomes restricts the ability to evaluate cause–effect relationships.

The review also examined whether Acid Mine Drainage processes are evident, effectively managed, or require further monitoring consideration. The Report found no evidence of net Acid Mine Drainage across both surface water and groundwater environments within the Cadia Hill Pit area.

Hydrobiology made a range of recommendations to enhance the robustness and effectiveness of the monitoring programs including, for example:

• strengthening the monitoring network design with a focus on formalising the site selection framework, clearly defining the rationale and site roles, and establishing a paired control–impact site design
• improving documentation, reporting, analysis and interpretation of results to better detect impacts, incorporating formal long-term time series analyses to detect trends and aligning the groundwater, surface water and aquatic ecology assessments to understand potential interactions and cumulative effects
• targeted sampling of surface waters during rainfall run-off events to better capture potential episodic impacts during worst-case conditions
• optimising the development and use of site-specific guideline values and management triggers.

These recommendations aim to strengthen the scientific rigour of the monitoring programs and increase their ability to detect and inform management of potential mine-related impacts.

Newmont response

• The EPA provided Newmont with a copy of the final Hydrobiology report on Monday 20 October. Newmont has provided the EPA with their response (PDF641KB).
• We will consider the report recommendations and Newmont's submission as we implement the recommendations where appropriate through licence variations.

Hydrobiology response 

• Hydrobiology was provided with Newmont’s submission. Hydrobiology has provided the EPA with their response (PDF104KB).

If you require documents in a different format, please email [email protected] 

The report and recommendations will be considered by the EPA’s water technical specialists to ensure that any future licence changes are evidence based and reflect environmental monitoring best practice.