Redwood Landfill Leachate Impoundment

About Redwood Landfill Leachate Impoundment

The primary purpose of Redwood Landfill Leachate Impoundment 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 Waste Management, Inc. (private). It impounds the Offstream.

The dam stands 10 feet tall and stretches 1,800 feet across, creates a reservoir covering 9 acres, and has a maximum storage capacity of 84 acre-feet. Completed in 1991, the structure is 35 years old.

This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in 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. An emergency action plan is in place for this dam. The most recent inspection on record was 11/18/2025.

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