Upper Silvis Reservoir Report
Nearby: Lower Silvis Whitman Lake
Last Updated: December 19, 2025
Upper Silvis is a hydroelectric dam located in Alaska along the Beaver Falls Creek and George Inlet.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1968, this rockfill dam stands at a height of 60 feet and has a storage capacity of 38,000 acre-feet, with a normal storage of 22,000 acre-feet. The dam has a low hazard potential and is primarily owned by a public utility, with oversight from the Federal Energy Regulatory Commission.
With a drainage area of 3.4 square miles and a maximum discharge of 6,000 cubic feet per second, Upper Silvis plays a crucial role in water resource management in the region. The dam's purpose is to generate hydroelectric power, contributing to renewable energy production while also providing water storage for various uses. Its location in the Ketchikan Gateway County of Alaska adds to its significance in the local water infrastructure.
Despite its age, Upper Silvis is maintained with regular inspections and a moderate risk assessment. The dam does not have a controlled spillway, but its uncontrolled spillway ensures safety in case of high water levels. With its strategic location and operational efficiency, Upper Silvis remains a key asset in the sustainable management of water resources and climate adaptation efforts in Alaska.
Year Completed |
1968 |
Dam Length |
135 |
Dam Height |
60 |
River Or Stream |
Beaver Falls Creek, George Inl |
Primary Dam Type |
Rockfill |
Surface Area |
300 |
Drainage Area |
3.4 |
Nid Storage |
38000 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
60 |
Seasonal Comparison
Weather Forecast
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Upper Silvis