Holter Dam

Holter Dam Quick Facts

Location: Lewis and Clark, Montana
Coordinates: 46.9913, -112.0047
River: Missouri River
Primary Purpose: Hydroelectric
Type: Gravity
Commissioned: 1918
Dam Height: 124 ft (38 m)
Dam Length: 1,364 ft (416 m)
Dam Capacity: 306,000 acre-ft (377,445 Ml)
Condition Assessment: Satisfactory
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Holter Dam Map

Holter Dam Information

Holter Dam is a gravity dam located about 8 miles from Craig, Mt, Lewis and Clark, Montana.

The dam, which is on the Missouri River, was primarily built for Hydroelectric purposes, but also serves for Flood Risk Reduction benefits.

The dam was designed by and commissioned in 1918 and is currently owned by NorthWestern Energy.

Holter Dam Structure

The Holter Dam is approximately 1,364 feet (416 m) long, 124 feet (38 m) high and has a structural volume of cubic yards (0 cubic metres).

Holter Dam Storage Capacity & Surface Area

The reservoir has a normal storage capacity of 245,000 acre-ft (302,203 Ml) and maximum capacity of 306,000 acre-ft (377,445 Ml).

The surface area of the reservoir is 4,550 acres (1,841 ha) and the total catchment area is 17,150 square miles (44,418 square kilometres).

Holter Dam Spillway

The dam has a 558 feet (170 m) wide controlled spillway with a maximum discharge capacity of 110000 cubic feet per second (3115 cubic metres per second).

Holter Dam Compared to Five Famous American Dams

Height (ft)
Length (Ft)
Storage Volume (acre-ft)
Drainage Area (sq miles)
 
Holter Dam
Lewis and Clark, Montana
Height (ft)
124
Length (Ft)
1,364
Storage Volume (acre-ft)
306,000
Drainage Area (sq miles)
17,150
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

Holter Dam Weather

Current Conditions at Holter Dam

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7-Day Forecast for Holter Dam

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Holter Dam Frequently Asked Questions

In which state is the Holter Dam?

Holter Dam is in Montana.

In which county is the Holter Dam?

Holter Dam is in Lewis and Clark County.

How high is the Holter Dam?

Holter Dam is 124 feet high.

How long is the Holter Dam?

Holter Dam is 1,364 feet long.

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More Dams in Lewis and Clark County:

Canyon Ferry Dam
Hauser Dam
Helena Valley Dam
Holter Dam
Nilan East Dam
Nilan North Dam
Willow Creek Bor Mt 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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