Ima Mill and Mine

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The Ima Mill and Mine Site is located near Patterson Creek in the Pahsimeroi Valley approximately 50 miles south of Salmon and 15 miles east of Challis, Idaho.

This mill processed tungsten ore from area mines. The waste materials from the refining process at the mill foundation included heavy concentrations of lead and zinc. However, the bulk of the tungsten tailings below the millsite consist mainly of fine- to medium-sand textured material and were deposited on both the north and south sides of Patterson Creek. The material covered an area approximately 250 feet in width by 2500 feet in length.

Based on the relatively benign contaminant levels measured in the tailings along patterson Creek, the remote nature of this site, and infrequent use by recreationists, the BLM determined that capping or complete removal of the tailings would likely not be warranted. However, proximity of the tailings to Patterson Creek and their potential as a significant source of sediment did inspire BLM to minimize negative impacts to the creek and address outstanding environmental, health, and safety risks.

Remediation emphasis was placed on those areas where tailings, waste rock, and slag had the potential to impact the creek with sediment or create health and safety risks to the public. Local resources such as talus, root wads, woody debris, etc., were used as bank armor for channel stabilization and to enhance fishery habitat in the area. Sand fences wre installed to reduce Aeolian movement of streamside tailings to allow revegetation efforts.

For additional information regarding this project, contact the area specialist or call the BLM Challis Field Office at (208) 879-6200.

Facts

Location

• 50 miles south of Salmon and 15 miles east of Challis, Idaho
• Near Patterson Creek in the Pahsimeroi Valley

History

• Mill produced tungsten ore from area mines

Impacts

• Millsite: Waste materials (tailings) from the refining process included heavy concentrations of lead and zinc
• Tailings along Patterson Creek: Cover the southern floodplain and terrace, comprising an area approximately 250 feet in width by 2500 feet in length

Risks

• Water quality
• Slag, waste materials at millsite, and physical safety hazards in close proximity to the road, creating health and safety risk to the public

Actions

• Stabilize stream channels with local materials
• Added sand fences to reduce movement of streamside tailings to allow revegetation
• Mitigate areas which threatened public health and safety

Challis Field Office  |  1151 Blue Mountain Road |  Challis, ID 83226
208-879-6200  |  Fax: 208-879-6219 |  Office hours: 7:45am - 4:30pm, M-F