Water Impacts

Americans regard pure, clean water as a birthright.  The hardrock mining industry, past and present, endangers that right.  Consider -

• Mining has contaminated more than 40 percent of the stream reaches of the headwaters of watersheds in the western U.S. (EPA, 2000)[1]   
• At least six major mine facilities have violated the Clean Water Act in the past two years.   (EPA, 2004)

Among the most prominent threats to western waters are -

• Acid Mine Drainage
• Perpetual Pollution
• Toxic Releases 
• Cyanide Use

Acid Mine Drainage

Acid mine drainage develops when mining operations (e.g. digging an open pit) expose sulfur-laden rock to air and water, leading to the formation of sulfuric acid.  Sulfuric acid in mine drainage harms rivers, streams and groundwater in two ways:

1. It kills aquatic life by lowering pH below that in which native organisms can reproduce and survive.  For example, acid mine drainage at the abandoned Iron Mountain Mine in California produces the most acidic water in the world, -3.6 pH -- 10,000 times more acidic than battery acid.
   
2. It dissolves toxic metals contained in the surrounding rock -- allowing them to pollute rivers, streams and groundwater too.  These toxic metals and metalloids, including arsenic, cadmium, lead and mercury are harmful to human and wildlife even in trace amounts.  Carried in water, the metals can travel long distances.  For example, toxic spills at the Summitville Mine in Colorado biologically killed an 18 mile stretch of the Alamosa River, requiring the nation's most costly mine cleanup.

Perpetual Pollution

Whether treated or not, acid mine drainage is a persistent problem. Acid will leach from a mine as long as the sulfur-bearing rock is exposed to air and water.  This can take thousands of years.  Roman mine sites in Great Britain continue to generate acid drainage 2,000 years after mining has ceased. In the United States, mines abandoned hundreds of years ago still release acid drainage into western waters. 

In order to protect western waters and aquatic life, this acid must then be treated in perpetuity, a task that can cost taxpayers billions of dollars. While evaluating the environmental impacts of the Newmont Mining's Phoenix Project in Nevada, scientists have predicted the mine will generate acid drainage for over 20,000 years.  EPA predicts that a $33.5 million trust fund would be required to pay for water treatment in perpetuity.

Toxic Releases

The EPA's Toxics Release Inventory shows that the hardrock mining industry is the nation's top toxic polluter.  In 2003 alone, the hardrock mining operations reported releases of 2.8 billion pounds of waste overall -- nearly half (46%) of all toxics released by all industries combined.   This amount included more than 335 million pounds of lead, 4 million pounds of mercury and 365 million pounds of arsenic.  The top ten largest polluters in the U.S. are mine sites, according to the TRI.

Cyanide Use

Cyanide is extremely toxic.  One teaspoon of a 2% solution can kill a person. In general, fish and other aquatic life are killed by cyanide concentrations in the microgram per liter range (part per billion), whereas bird and mammal deaths result from cyanide concentrations in the milligram per liter range (part per million). [2]

The mining industry uses large quantities of cyanide:  over 180,000 metric tons each year.  And the mining industry often uses this cyanide irresponsibly.  Open pit cyanide heap leach mining involves spraying a cyanide solution over heaps of ore -- then collecting the now mineral rich cyanide solution from the bottom of the heaps.  This process happens in the open environment.  The result:  spills.  For example:

• Grouse Creek, Idaho.  A 40-minute cyanide spill at the Grouse Creek gold mine in Idaho resulted in the contamination of a nearby creek at 1.31 parts per million, 60 times higher than levels toxic to fish.
• Zortman-Landusky Mine, Montana.  52,000 gallons of cyanide solution poisoned the drainage that supplies fresh drinking water for the town of Zortman.  A mine employee discovered the accident when he noticed the smell of cyanide in his tap water at home.
• Homestake, South Dakota.  Six to seven tons of cyanide-laced tailings spilled from the Homestake Mine into Whitewood Creek in the Black Hills of South Dakota, resulting in a substantial fish kill.

Furthermore, cyanide reacts with many other elements and is known to breakdown into several hundred different cyanide-related compounds. Despite the risks posed by these breakdown compounds, mines are not required to monitor or report these chemicals. Evidence does show that cyanide compounds can linger in plant and fish tissues and can persist in the environment for long periods of time.

For More Information

References

1) The U.S. Environmental Protection Agency, Liquid Assets 2000: Americans Pay for Dirty Water (March, 2006).

2) Mineral Policy Center, MPC Fact Sheet: Cyanide.