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Chapter 7: Human Alterations to Riparian Areas
Mining Activities
- Despite the fact that only a small percentage of the United States land has been mined, their impacts can be very severe to riparian areas.
- When mining dredges valley bottoms not only is all the vegetation removed but also several feet of soils.
- Mining operation can use substantial amounts of surface and/or ground water.
- Mining and smelting operations can pollute the adjacent surface water. Drainage and runoff from unprotected spoil piles can carry arsenic, lead, sediments, and can be highly acidic.
- Open pit mines and the spoil piles associated with processing facilities can significantly disrupt surface runoff patterns.
- Mining gravel from stream terraces can lead to channel incision, impact riparian vegetation, and influence groundwater. The gravel that is extracted is typically used by the building industry that continues to grow with Arizona’s population.
- Mining operations can leave large areas bare of vegetation that can increase overland flow, sediment production, and stream incision.
Figure 7.22. Open pit copper mining (left) and gravel mining (right) in Arizona.
- Mining impacts can be significantly reduced with proper rehabilitation efforts although in some cases it is very difficult and/or expensive.
- When large areas of bare ground are exposed, well-designed detention ponds can significantly reduce overland flow and sediment to adjacent rivers and streams.
- Reclamation of mined areas can be much more successful by removing, stockpiling, and reusing the topsoils of these areas.
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