January Detention Dam

January Detention Dam is a gravity dam located in Valley County, Montana, built in 1960. It carries a Low hazard potential classification and has a unsatisfactory condition assessment.

About January Detention Dam

The primary purpose of January Detention Dam 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 Doi Blm (federal). It impounds the Willow Ck./milk River near Nashua.

The dam stands 31 feet tall and stretches 946 feet across, creates a reservoir covering 38 acres, has a maximum storage capacity of 387 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1960, the structure is well into its service life at over 50 years old.

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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. The most recent inspection on record was 11/02/2019.

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Low HazardUnsatisfactory ConditionEmergency Action Plan: Not Required

Location

StateMontana
CountyValley
Nearest CityNashua
River/StreamWillow Ck./milk River
Coordinates48.08066, -106.75672

Physical Characteristics

Dam TypeGravity
NID Height31 ft
Dam Length946 ft
Year Completed1960 (66 years old)

Storage & Hydraulics

NID Storage520 acre-ft
Max Storage387 acre-ft
Normal Storage520 acre-ft
Surface Area38 acres
Drainage Area6 sq mi
Spillway TypeUncontrolled

Ownership & Safety

PurposeFire Protection, Stock, Or Small Fish Pond
OwnerDOI BLM
Owner TypeFederal
Hazard ClassificationLow
Condition AssessmentUnsatisfactory
Last Inspection11/02/2019
Emergency Action PlanNot Required

Identifiers

NID IDMT00672
Federal IDMT00672
More InfoState Dam Safety Program

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