Mystic Lake Dam

Mystic Lake Dam Quick Facts

Location: Stillwater, Montana
Coordinates: 45.2254, -109.7601
River: West Rosebud Creek River
Primary Purpose: Hydroelectric
Type: Arch
Commissioned: 1927
Dam Height: 45 ft (14 m)
Dam Length: 368 ft (112 m)
Dam Capacity: 21,000 acre-ft (25,903 Ml)
Condition Assessment: Satisfactory
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Mystic Lake Dam Map

Mystic Lake Dam Information

Mystic Lake Dam is an arch dam located about 25 miles from Fishtail, Mt, Stillwater, Montana.

The dam, which is on the West Rosebud Creek River, was primarily built for Hydroelectric purposes, but also serves for Recreation benefits.

The dam was designed by and commissioned in 1927 and is currently owned by NorthWestern Energy.

Mystic Lake Dam Structure

The Mystic Lake Dam is approximately 368 feet (112 m) long, 45 feet (14 m) high and has a structural volume of cubic yards (0 cubic metres).

Mystic Lake Dam Storage Capacity & Surface Area

The reservoir has a normal storage capacity of 20,800 acre-ft (25,656 Ml) and maximum capacity of 21,000 acre-ft (25,903 Ml).

The surface area of the reservoir is 446 acres (180 ha) and the total catchment area is 45 square miles (118 square kilometres).

Mystic Lake Dam Spillway

The dam has a 300 feet (91 m) wide uncontrolled spillway with a maximum discharge capacity of 30000 cubic feet per second (850 cubic metres per second).

Mystic Lake Dam Compared to Five Famous American Dams

Height (ft)
Length (Ft)
Storage Volume (acre-ft)
Drainage Area (sq miles)
 
Mystic Lake Dam
Stillwater, Montana
Height (ft)
45
Length (Ft)
368
Storage Volume (acre-ft)
21,000
Drainage Area (sq miles)
45
Hoover Dam
Clark County, Nevada
Height (ft)
730
Length (Ft)
1,244
Storage Volume (acre-ft)
30,237,000
Drainage Area (sq miles)
167,800
Grand Coulee Dam
Okanogan County, Washington
Height (ft)
550
Length (Ft)
5,673
Storage Volume (acre-ft)
9,562,0000
Drainage Area (sq miles)
74,100
Theodore Roosevelt Dam
Maricopa County, Arizona
Height (ft)
357
Length (Ft)
1,208
Storage Volume (acre-ft)
3,411,500
Drainage Area (sq miles)
5,736
Oroville Dam
Butte County, California
Height (ft)
235
Length (Ft)
6,920
Storage Volume (acre-ft)
3,540,000
Drainage Area (sq miles)
3,611
Glen Canyon Dam
Coconino County, Arizona
Height (ft)
216
Length (Ft)
1,565
Storage Volume (acre-ft)
29,875,000
Drainage Area (sq miles)
108,355

Mystic Lake Dam Weather

Current Conditions at Mystic Lake Dam

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7-Day Forecast for Mystic Lake Dam

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Mystic Lake Dam Frequently Asked Questions

In which state is the Mystic Lake Dam?

Mystic Lake Dam is in Montana.

In which county is the Mystic Lake Dam?

Mystic Lake Dam is in Stillwater County.

How high is the Mystic Lake Dam?

Mystic Lake Dam is 45 feet high.

How long is the Mystic Lake Dam?

Mystic Lake Dam is 368 feet long.

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Mystic Lake Dam

Condition Assessment Classification

Satisfactory

No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.

Fair

No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum

Poor

A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.

Unsatisfactory

A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.

Not Rated

The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.

Not Available

Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High

Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.

Significant

Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.

Low

Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner’s property.

Undetermined

Dams for which a downstream hazard potential has not been designated or is not provided.

Not Available

Dams for which the downstream hazard potential is restricted to approved government users.

Source: National Inventory of Dams

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