Mason Reservoir Report
Last Updated: December 13, 2025
Mason, also known as M-107, is a federal-owned dam located in Baker, Oregon, along the Powder River.
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Summary
Built in 1967 by the Bureau of Reclamation, Mason primarily serves the purpose of flood risk reduction and irrigation. The dam stands at an impressive height of 173 feet and has a storage capacity of 111,500 acre-feet, with a normal storage level at 78,500 acre-feet. The dam's high hazard potential underscores the importance of careful monitoring and maintenance.
Managed by the Bureau of Reclamation, Mason's design includes rockfill construction with an arch core type and a rock foundation. The dam spans 895 feet in length and covers a surface area of 2,235 acres, impacting a drainage area of 165 square miles. With a maximum discharge capacity of 1,210 cubic feet per second, Mason plays a crucial role in managing water resources and mitigating flood risks in the region. While the dam's condition assessment is currently not available, its last inspection in September 2020 and high hazard potential highlight the need for continued vigilance and emergency preparedness.
In the event of an emergency, it is essential for stakeholders to ensure that the Emergency Action Plan (EAP) is up to date and meets guidelines for effective response. With its strategic location and significant impact on the surrounding area, Mason's role in flood risk reduction and water management underscores the importance of ongoing monitoring and risk assessment. As a key asset in the region's water resource infrastructure, Mason serves as a testament to the critical role that dams play in safeguarding communities and ecosystems from the impacts of climate change and extreme weather events.
Year Completed |
1967 |
Dam Length |
895 |
Dam Height |
167 |
River Or Stream |
POWDER RIVER |
Primary Dam Type |
Rockfill |
Surface Area |
2235 |
Hydraulic Height |
159 |
Drainage Area |
165 |
Nid Storage |
111500 |
Structural Height |
173 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
173 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Union Creek
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Millers Lane
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Millers Lane Campground
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Southwest Shore
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Southwest Shore Campground
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Mason