Energy, Mines and Resources

Effects of Placer Mining

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Effects of Placer Mining

For more info on how placer mining works, see our Placer Mining section.  Placer mining can affect fish and fish habitat when:

  • Water is withdrawn from a stream for sluicing.
  • Sediment from sluicing is discharged into streams.
  • Streams are diverted to get at gold underneath.
  • Other in-stream activities are used, such as construction of dams, dikes, settling ponds, etc.


When stream channels are changed or sediment concentrations are increased, it can affect benthic invertebrates in the stream. Their populations can decline, or the species types may change. These activities can place stress on fish populations too. The effects may include:

  • Fish reproduction may be irregular, less successful or absent.
  • Fish growth may be reduced.
  • Fish body condition may be reduced.
  • Fish survival may be reduced (in extreme cases).

Placer mining is not the only factor that can affect fish habitat. Other factors include:

  • Natural variations in rainfall and climate
  • Forest fires
  • Landslides
  • Other human activity related to communities, other industries, recreation, etc.