Rock Island Reservoir Report
Last Updated: December 15, 2025
Rock Island is a gravity-type dam located on the Columbia River in Washington, with a height of 71 feet and a hydraulic height of 55.1 feet.
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Summary
Completed in 1932, the dam serves the primary purpose of hydroelectric power generation and flood risk reduction. It has a storage capacity of 131,000 acre-feet and a drainage area of 89,400 square miles, making it a crucial water resource infrastructure in the region.
Managed by the Federal Energy Regulatory Commission, Rock Island has a controlled spillway width of 961 feet and 31 slide gates for water control. With a hazard potential rated as high and a risk assessment indicating very high risk, the dam's emergency action plan is crucial for public safety. Despite its age, the dam's condition assessment is not available, emphasizing the need for ongoing monitoring and maintenance to ensure its structural integrity and long-term functionality for water resource management in the area.
Rock Island's association with Stone & Webster Engineering Corporation underscores its historical significance in water resource development. As a key player in the region's hydroelectric landscape, the dam's operations and maintenance are vital for ensuring water security and climate resilience in the face of changing environmental conditions. For water resource and climate enthusiasts, Rock Island represents a blend of engineering excellence, environmental stewardship, and critical infrastructure for sustainable water management in the Pacific Northwest.
Year Completed |
1932 |
Dam Length |
3108 |
Dam Height |
71 |
River Or Stream |
Columbia River |
Primary Dam Type |
Gravity |
Surface Area |
3120 |
Hydraulic Height |
55.1 |
Drainage Area |
89400 |
Nid Storage |
131000 |
Structural Height |
61 |
Outlet Gates |
Slide (sluice gate) - 31 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
71 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Wenatchee River At Monitor
|
12000cfs |
Entiat River Near Entiat
|
1050cfs |
Wenatchee River At Peshastin
|
11200cfs |
Mad River At Ardenvoir
|
197cfs |
Chelan River At Chelan
|
756cfs |
Icicle Creek Above Snow Creek Near Leavenworth
|
1750cfs |
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.
Rock Island
Russ Road Chelan County