Lower Silvis Reservoir Report
Nearby: Upper Silvis Whitman Lake
Last Updated: December 19, 2025
Lower Silvis is a hydroelectric dam located in Alaska, specifically in the Ketchikan Gateway area.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1954, this rockfill dam stands at a height of 32 feet and has a storage capacity of 1600 acre-feet, with a normal storage level of 1400 acre-feet. The dam is situated on Beaver Falls Creek and George Inlet, contributing to the local water resources and power generation.
Managed by the Federal Energy Regulatory Commission, Lower Silvis serves a primary purpose of hydroelectric power generation. With a spillway type classified as "Uncontrolled" and a low hazard potential, the dam has a moderate risk assessment rating of 3. Although the condition assessment is currently listed as "Not Available," the dam undergoes inspections every 3 years to ensure operational safety and compliance with regulatory standards.
Overall, Lower Silvis plays a crucial role in the water resource management and energy production in the region. Its strategic location and design make it a significant asset for both the local government and environmental enthusiasts interested in sustainable energy solutions and climate resilience.
Year Completed |
1954 |
Dam Length |
140 |
Dam Height |
32 |
River Or Stream |
Beaver Falls Creek, George Inl |
Primary Dam Type |
Rockfill |
Surface Area |
68 |
Drainage Area |
1 |
Nid Storage |
1600 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
32 |
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.
Lower Silvis