Potosi Lake Dam

Potosi Lake Dam is a rockfill dam located in Washington County, Missouri, built in 1947. It carries a High hazard potential classification.

About Potosi Lake Dam

The primary purpose of Potosi Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Potosi Lake Village (private). It impounds the Trib-big River near Leadwood.

The dam stands 33 feet tall, creates a reservoir covering 20 acres, has a maximum storage capacity of 438 acre-feet, and collects water from a drainage area of 555 square miles. Completed in 1947, the structure is well-established, with more than 75 years of service.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. The most recent inspection on record was 06/25/1980. That was 45 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.

At 33 feet, this dam is taller than 78% of dams nationwide.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Missouri dam safety program can provide more specific information about emergency planning for this structure.

Search for dams near your address to see all dams in your area with hazard classifications and safety data.

High HazardNot Rated ConditionEmergency Action Plan: Not Required

Location

StateMissouri
CountyWashington
Nearest CityLeadwood
River/StreamTrib-big River
Coordinates37.88179, -90.68024

Physical Characteristics

Dam TypeRockfill
NID Height33 ft
Dam Height33 ft
Year Completed1947 (79 years old)

Storage & Hydraulics

NID Storage438 acre-ft
Max Storage438 acre-ft
Normal Storage438 acre-ft
Surface Area20 acres
Drainage Area555 sq mi

Ownership & Safety

PurposeRecreation
OwnerPOTOSI LAKE VILLAGE
Owner TypePrivate
Hazard ClassificationHigh
Condition AssessmentNot Rated
Last Inspection06/25/1980
Emergency Action PlanNot Required

Identifiers

NID IDMO30477
Federal IDMO30477
More InfoState Dam Safety Program

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