No. 5a

About No. 5a

The primary purpose of No. 5a is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is owned by Tata Chemicals North America (private). It impounds the Allied Draw near Flaming Gorge Reservoir.

The dam stands 70 feet tall and stretches 3,500 feet across, creates a reservoir covering 200 acres, has a maximum storage capacity of 5,556 acre-feet, and collects water from a drainage area of 200 square miles. Completed in 1975, the structure is well into its service life at over 50 years old.

This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 04/16/2024.

At 70 feet, this dam is taller than 96% of all dams in the United States.

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