Johnson Reservoir

Johnson Reservoir is an earth dam located in Dawson County, Montana, built in 1937. It carries a Low hazard potential classification.

About Johnson Reservoir

The primary purpose of Johnson Reservoir is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by State Of Montana, D.f.w.p. (state). It impounds the Deer Creek near Intake.

The dam stands 21 feet tall and stretches 1,500 feet across, creates a reservoir covering 35 acres, has a maximum storage capacity of 351 acre-feet, and collects water from a drainage area of 17 square miles. Completed in 1937, 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. The most recent inspection on record was 07/17/2024.

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Low Hazard ConditionEmergency Action Plan: Not Required

Location

StateMontana
CountyDawson
Nearest CityIntake
River/StreamDeer Creek
Coordinates47.31420, -105.09740

Physical Characteristics

Dam TypeEarth
NID Height21 ft
Dam Height21 ft
Dam Length1,500 ft
Year Completed1937 (89 years old)

Storage & Hydraulics

NID Storage351 acre-ft
Max Storage351 acre-ft
Normal Storage208 acre-ft
Surface Area35 acres
Drainage Area17 sq mi
Spillway TypeUncontrolled

Ownership & Safety

PurposeRecreation
OwnerSTATE OF MONTANA, D.F.W.P.
Owner TypeState
Hazard ClassificationLow
Last Inspection07/17/2024
Emergency Action PlanNot Required

Identifiers

NID IDMT00110
Federal IDMT00110
More InfoState Dam Safety Program

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