Black Hills Power & Light First Enlargement

Black Hills Power & Light First Enlargement is an earth dam located in Weston County, Wyoming, built in 1940. It carries a Low hazard potential classification and has a fair condition assessment.

About Black Hills Power & Light First Enlargement

Black Hills Power & Light First Enlargement is a dam in Weston, Wyoming. The dam is owned by Black Hills Power And Light (public utility). It impounds the East Branch Poison Creek near Osage.

The dam stands 27 feet tall and stretches 700 feet across, creates a reservoir covering 30 acres, and has a storage capacity of 195 acre-feet. Completed in 1940, 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 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 04/29/2021.

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Low HazardFair ConditionEmergency Action Plan: Not Required

Location

StateWyoming
CountyWeston
Nearest CityOsage
River/StreamEast Branch Poison Creek
Coordinates43.97280, -104.40780

Physical Characteristics

Dam TypeEarth
NID Height27 ft
Dam Height27 ft
Dam Length700 ft
Year Completed1940 (86 years old)

Storage & Hydraulics

NID Storage195 acre-ft
Normal Storage195 acre-ft
Surface Area30 acres
Spillway TypeUncontrolled

Ownership & Safety

PurposeOther
OwnerBLACK HILLS POWER AND LIGHT
Owner TypePublic Utility
Hazard ClassificationLow
Condition AssessmentFair
Last Inspection04/29/2021
Emergency Action PlanNot Required

Identifiers

NID IDWY01520
Federal IDWY01520
More InfoState Dam Safety Program

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