Cooper

Cooper is an earth dam located in Natrona County, Wyoming, built in 1933. It carries a Low hazard potential classification and has a poor condition assessment.

About Cooper

The primary purpose of Cooper is fire protection, stock, or small fish pond. The dam maintains a small impoundment used for fire suppression, livestock watering, or as a fish pond. The dam is owned by Dona Marie Vold-larsen (private). It impounds the Branch Of South Powder River near Arvada.

The dam stands 16 feet tall and stretches 1,450 feet across, creates a reservoir covering 21 acres, and has a maximum storage capacity of 232 acre-feet. Completed in 1933, the structure is well-established, with more than 75 years of service.

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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 05/24/2023.

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Low HazardPoor ConditionEmergency Action Plan: Not Required

Location

StateWyoming
CountyNatrona
Nearest CityArvada
River/StreamBranch Of South Powder River
Coordinates43.00333, -107.21333

Physical Characteristics

Dam TypeEarth
NID Height16 ft
Dam Height16 ft
Dam Length1,450 ft
Year Completed1933 (93 years old)

Storage & Hydraulics

NID Storage232 acre-ft
Max Storage232 acre-ft
Normal Storage95 acre-ft
Surface Area21 acres
Spillway TypeUncontrolled

Ownership & Safety

PurposeFire Protection, Stock, Or Small Fish Pond
OwnerDONA MARIE VOLD-LARSEN
Owner TypePrivate
Hazard ClassificationLow
Condition AssessmentPoor
Last Inspection05/24/2023
Emergency Action PlanNot Required

Identifiers

NID IDWY01009
Federal IDWY01009
More InfoState Dam Safety Program

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