Intersection of Wildfire and Legacy Mining Poses Risks to Water Quality

Area of Science:

• Environmental Science
• Geochemistry
• Water Resource Management

Background:

• Mining and wildfires are significant landscape disturbances.
• Both activities increase erosion and transport of sediment and metals to water bodies.
• The combined impact of mining and wildfire in a watershed amplifies risks to water supplies and ecosystems.

Purpose of the Study:

• To describe the mechanisms by which the intersection of mining and wildfire activities leads to elevated metal concentrations in downstream waters.
• To highlight the amplified risks to water supplies when these disturbances co-occur.
• To underscore the need for improved management strategies.

Main Methods:

• This study is a review and synthesis of known geochemical and hydrological processes.
• It identifies and describes five key mechanisms of metal transport.
• The work integrates understanding of disturbance ecology and contaminant transport.

Main Results:

• Five primary mechanisms were identified: (1) metal-rich ash and soil conveyance, (2) increased metal dissolution from mine waste, (3) enhanced erosion of mine waste sediment, (4) remobilization of contaminated floodplain sediments, and (5) increased metal transport from underground mines.
• These mechanisms collectively elevate metal concentrations in surface waters.
• The synergistic effect of mining and wildfire poses a substantial geochemical hazard.

Conclusions:

• The intersection of mining and wildfire presents a complex geochemical hazard to water resources.
• Predicted increases in wildfire activity exacerbate these risks.
• Improved mapping, monitoring, modeling, and mitigation are crucial for managing water availability and quality.