Gold and silver mining in the Telluride and Ouray districts of Colorado has a rich history dating back to the 1800s. In 1939, Newmont consolidated a number of the area’s mining claims to form the Idarado Mining Company.

When mining operations ceased at Idarado in 1978, the reclamation phase began, as did a legal battle between Newmont and the State of Colorado related to the extent of the impacts associated with past mining activities and the entities responsible for them. After more than a decade of environmental studies, legal proceedings and negotiations, in 1992 Idarado and the State of Colorado settled the lawsuit and agreed to a Remedial Action Plan (RAP), which detailed the activities Idarado would undertake to apply current day environmental standards to more than a century of mining impacts.

By 1997, Idarado had completed nearly all the requirements of the RAP. During this time, the relationship between Newmont and the State of Colorado evolved from one characterized by conflict to one of trust and working toward a shared goal to protect the environment.

Many of the RAP elements were considered innovative for the time but are now standard practice. Examples include:

• Remediating tailings piles by revegetating and creating an environment favorable to plant growth and not subject to wind or water erosion; and
• Improving water quality via the “keeping water clean” strategy through source control techniques that divert clean rainfall and snow melt around sources such as waste rock piles, tailings and underground mine workings where the water could pick up metals resulting in acidification of the water.

Since 2004, Idarado has met its zinc concentration commitment for the San Miguel River, and the tailings piles support a robust plant community that provides erosion stability. The primary challenge that remains is the acidity and high metal content – caused by both natural and historic mining sources – in Red Mountain Creek. The RAP requires Idarado to reduce zinc levels in Red Mountain Creek by 50 percent from pre-remediation levels. Since completion of the RAP activities in 1997, zinc levels are down approximately 25 percent. New passive water treatment systems are being tested in combination with other methods and systems to find a sustainable means of achieving the remaining 25 percent reduction. Other actions being taken to adapt to changing site conditions and to mitigate potential risks include:

• Installing weather stations to better assess rainfall and snowpack conditions and their impact on draining flows;
• Designing a concrete bulkhead to more efficiently and effectively manage the variations in peak portal discharge flows;
• Installing continuous water monitoring stations that measure discharge flows and water quality parameters; and
• Using video and drone technologies to understand shifting meteorological, glaciological and hydrogeological conditions that may be influencing historic flow patterns.

These efforts and the supporting data are critical to mitigating risks, maintaining trust and positive relationships with stakeholders, and ensuring compliance with our commitments well into the future.

The rich history of the Idarado mine was featured in 2018 in the local Telluride and Ouray newspapers in a 10-part series, “The Mine Next Door” that marked 40 years since mining activities ceased.

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