Hiram M. Chittenden Locks And Dam Reservoir Report

Last Updated: December 15, 2025

The Hiram M.


°F

°F

mph

Wind

%

Humidity

Summary

Chittenden Locks and Dam, located in Seattle, Washington, serves as a vital water resource infrastructure for navigation, fish and wildlife management, and recreation. Built in 1916 by the US Army Corps of Engineers, this gravity dam stands at a height of 63 feet and has a spillway width of 192 feet. With a storage capacity of 458,000 acre-feet, the dam plays a crucial role in managing water levels and preventing downstream flooding in the region.

Despite being over a century old, the Hiram M. Chittenden Locks and Dam is well-maintained and continues to meet its operational safety goals. The risk assessment conducted in 2018 categorized the project's risk as moderate, primarily driven by the potential for large magnitude earthquakes in the region. To mitigate risks, USACE has implemented various measures, including regular inspections, dam repairs, and upgrades to modernize the infrastructure. Additionally, the project utilizes an earthquake shaking early warning system and collaborates closely with local emergency managers to ensure preparedness for any potential emergencies.

In conclusion, the Hiram M. Chittenden Locks and Dam serves as a critical piece of infrastructure in the Pacific Northwest, providing essential services for navigation, wildlife conservation, and flood control. With ongoing risk management measures in place, the dam continues to play a vital role in safeguarding the surrounding communities and ecosystem, ensuring the sustainable management of water resources in the region.

Year Completed

1916

Dam Length

240

River Or Stream

CEDAR RIVER, SAMMAMISH RIVER

Primary Dam Type

Gravity

Surface Area

25000

Length Of Locks

825

Hydraulic Height

25

Drainage Area

607

Nid Storage

458000

Structural Height

63

Hazard Potential

High

Nid Height

63
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

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.