Lower Granite Lock And Dam - North Levee Reservoir Report
Last Updated: December 15, 2025
The Lower Granite Lock and Dam - North Levee, also known as the Lewiston Levees, is a federal structure owned and managed by the US Army Corps of Engineers in Washington state.
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Summary
Completed in 1974, the primary purpose of the dam is navigation, with additional functions including fish and wildlife ponds, hydroelectric power generation, and recreational activities. Situated on the Snake River within the Walla Walla District, the dam is an important part of the region's water resource infrastructure.
Despite its high hazard potential, the dam is regularly inspected and monitored to assess and manage flood risks associated with its operations. The US Army Corps of Engineers prioritizes activities that mitigate risks, engages with local emergency managers, and updates emergency action plans to ensure readiness in case of a dam-related emergency. By working closely with relevant stakeholders and implementing maintenance and repair measures as needed, the USACE aims to ensure the structural integrity and safety of the dam for both navigation and flood control purposes. More detailed information on risk management measures specific to this dam will be added in the future.
Year Completed |
1974 |
River Or Stream |
Snake |
Primary Dam Type |
Concrete |
Hazard Potential |
High |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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 Granite Lock And Dam - North Levee
Steelhead Park