Upper Silvis Dam, Alaska, USA

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Quick Facts About Upper Silvis Dam

Location: Ketchikan Gateway, Alaska
Coordinates: 55.37996, -131.518934
River: Beaver Falls Creek, George Inl River
Primary Purpose: Hydroelectric
Type: Rockfill Other
Commissioned: 1968
Dam Height: 60 ft (18 m)
Dam Length: 135 ft (41 m)
Dam Capacity: 38,000 acre-ft (46,872 Ml)
Condition Assessment: Satisfactory

Upper Silvis Dam Map

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Upper Silvis Dam Information

Upper Silvis Dam is a rockfill other dam located in None, Ketchikan Gateway, Alaska.

The dam, which is on the Beaver Falls Creek, George Inl River, was primarily built for Hydroelectric purposes, but also serves for benefits.

The dam was designed by and commissioned in 1968 and is currently owned by City of Ketchikan.

Upper Silvis Dam Structure

The Upper Silvis Dam is approximately 135 feet (41 m) long, 60 feet (18 m) high and has a structural volume of 0 cubic yards (0 cubic metres).

Upper Silvis Dam Storage Capacity & Surface Area

The reservoir has a normal storage capacity of 22,000 acre-ft (27,137 Ml) and maximum capacity of 38,000 acre-ft (46,872 Ml).

The surface area of the reservoir is 300 acres (121 ha) and the total catchment area is 3 square miles (9 square kilometres).

Upper Silvis Dam Spillway

The dam has a 54 feet (16 m) wide uncontrolled spillway with a maximum discharge capacity of 6000 cubic feet per second (170 cubic metres per second).

Upper Silvis Dam Compared to Four Famous American Dams

Upper Silvis Dam
Ketchikan Gateway, Alaska
Hoover Dam
Clark County, Nevada
Grand Coulee Dam
Okanogan County, Washington
Theodore Roosevelt Dam
Maricopa County, Arizona
Glen Canyon Dam
Coconino County, Arizona
Height (ft) 60 730 550 357 216
Length (Ft) 135 1,244 5,673 6,920 1,565
Storage Volume (acre-ft) 38,000 30,237,000 9,562,000 3,540,000 29,875,000
Drainage Area (sq miles) 3 167,800 74,100 3,611 108,355

Upper Silvis Dam Weather

Current Conditions at Upper Silvis Dam

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7-Day Forecast for Upper Silvis Dam

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Upper Silvis Dam Frequently Asked Questions

In which state is the Upper Silvis Dam?

Upper Silvis Dam is in Alaska.

In which county is the Upper Silvis Dam?

Upper Silvis Dam is in Ketchikan Gateway County.

How high is the Upper Silvis Dam?

Upper Silvis Dam is 60 feet high.

How long is the Upper Silvis Dam?

Upper Silvis Dam is 135 feet long.

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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