Cottonwood (Drewsey) Reservoir Report
Nearby: Altnow Reservoir Stallard Dam
Last Updated: December 13, 2025
Cottonwood (Drewsey) is a vital water resource infrastructure located in Harney County, Oregon, specifically designed for irrigation purposes along Cottonwood Creek.
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Summary
Built in 1967, this dam has a structural height of 83 feet and a storage capacity of 4500 acre-feet, serving a drainage area of 34.3 square miles. With a significant hazard potential, the dam's primary purpose is to provide water for agricultural activities in the region, making it a crucial asset for local government operations.
Managed by the Natural Resources Conservation Service, Cottonwood (Drewsey) features an uncontrolled spillway type with a maximum discharge capacity of 1450 cubic feet per second. Despite being rated as "Not Rated" in terms of condition assessment, the dam undergoes regular inspections every three years to ensure its structural integrity and safety. In the event of emergencies, the dam's emergency action plan readiness and risk management measures play a pivotal role in mitigating potential risks and safeguarding the surrounding areas from inundation.
The dam's location in Drewsey, Oregon, underlines its importance in water resource management within the region, with oversight provided by the Oregon Water Resources Department. With its moderate risk assessment rating of 3, Cottonwood (Drewsey) signifies the delicate balance between water supply for irrigation and the potential hazards associated with dam infrastructure. As a key component of the local water supply system, this dam serves as a critical link in ensuring sustainable water access for agricultural activities in the area.
Year Completed |
1967 |
Dam Length |
335 |
Dam Height |
73 |
River Or Stream |
COTTONWOOD CREEK |
Primary Dam Type |
Other |
Surface Area |
112 |
Hydraulic Height |
70 |
Drainage Area |
34.3 |
Nid Storage |
4500 |
Structural Height |
83 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
Significant |
Nid Height |
83 |
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.
Cottonwood (Drewsey)
North Fork Malheur River
Malheur Nf
Middle Fork Malheur (Including Bluebucket Creek)