Waste Management Outlook for Mountain Regions

CASE STUDY

Acid mine drainage in mountain areas – a slow motion environmental problem

The Gold King mine, located in the San Juan Mountains of Colorado, last operated in 1922 but has been in the news in recent years due to an unwanted legacy that had been slowly building up in the abandoned gold and silver mine. The legacy was acid mine drainage. In 2015 officers from the United States Environmental Protection Agency (EPA) investigating a slow leak at the mine entrance, accidently released 3million gallons of this toxic material (Chief et al 2016). Much of the contaminated water and sludge flowed into the Animas River, the upper reaches of which were already adversely affected by decades of slow seepage of acidic water from the mine. The Animas River flows into the San Juan River and ultimately into the Colorado River (traversing 5 states - Colorado, Utah, NewMexico, Arizona, Nevada, and California).

The sudden release of large volumes of toxic material, that included lead and arsenic, had a widespread impact that extended far downstream, disrupting the drinking water supply of towns and halting recreational activities and irrigation of crops leading to heavy crop failure. The impact of the acid mine drainage on water quality and river bed sediments appears to have been fairly short lived (the Animas River had poor water quality pre-spill) as snow melt helped to dilute the river water and wash away contaminated sediment (Cohen 2015). However, the spill had serious financial consequences for many people, due to tourism and agricultural losses. As a consequence, many states and individuals are suing the EPA for damages (Roberts 2016).

Retention ponds set up by the US EPA following the accidental release of acid mine water from the Gold King mine in Colorado in 2015. The water in the ponds is treated with lime which raises the pH and sodium hydroxide solution which facilitates sedimentation of the metals prior to release of the water. The process is time consuming and expensive. As of August 2016, the US EPA had dedicated $29 million to the clean-up and remediation effort (US EPA 2016). Photo © Wikimedia/EPA

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