Tree water use and sensitivity to contaminated mine water

Ranger uranium mine is surrounded by Kakadu National Park. The mine has ceased operations and rehabilitation works are due to be completed by 2026. Spring-fed monsoon vine forests and riparian (riverbank) vegetation depend on soil and groundwater and provide essential habitat for the highly diverse aquatic ecosystems of the freshwater Magela Creek, which flows through the mine lease. Contamination of shallow groundwater with mine wastewater after rehabilitation of the site could have significant impact on this riparian vegetation and stream health.

This study has improved the knowledge of how common woody riparian plants use and depend on groundwater, which will help predict impacts from contaminants and inform mine closure and monitoring.

The project:

  • used different isotope tracers to quantify the groundwater dependence of riparian vegetation in the Magela Creek catchment, which flows through Kakadu National Park and the Ranger uranium mine lease
  • tested the sensitivity of common woody riparian species to the contaminant magnesium sulfate (MgSO4; a salt) to provide a risk assessment of impact from potentially contaminated surface and/or groundwater
  • quantified risks to riparian vegetation associated with the discharge of mine-related contaminants into surface and groundwater through analysis and modelling of and surface and groundwater.

Ranger uranium mine locator satellite image

Location of Ranger uranium mine adjacent to Kakadu National Park.

  • Samantha Setterfield and Adam Bourke in the CDU shadehouse.
  • Measuring plant physiology after treating plants with various concentrations of MgSO4.
  • Measuring plant height regularly helped to identify any positive or negative effects on plant growth. Photo Fi Freestone.
  • Project team assessing Magela Creek riparian vegetation. Photo NESP Northern Hub.
  • UWA, CDU and SSB teams improving understanding of how trees use groundwater in the Magela Creek catchment.
  • Magela Creek in the wet season. As these flood flows recede, the water table suggests that sub-surface flow occurs from shallow parts of the weathered bedrock aquifer to the sand-bed area.