Greaser Lake Reservoir Reservoir Report
Nearby: Calderwood Reservoir Mud Lake
Last Updated: December 13, 2025
Greaser Lake Reservoir, located in Lake County, Oregon, is a privately owned Earth dam structure built in 1963 primarily for irrigation purposes.
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Summary
The reservoir has a storage capacity of 20,000 acre-feet and a surface area of 4,000 acres, serving the local agricultural community in the region. With a low hazard potential and a not rated condition assessment, Greaser Lake Reservoir plays a vital role in water resource management and climate adaptation efforts in the area.
The dam, standing at a height of 10 feet with a hydraulic height of 8 feet, is situated on Twenty Mile Creek and has a maximum discharge capacity of 1,440 cubic feet per second. The reservoir has no downstream settlement and is regulated by the Oregon Water Resources Department, ensuring proper inspection, enforcement, and permitting processes are in place. With a slide (sluice gate) outlet gate and a last inspection date in 2015, Greaser Lake Reservoir continues to be a crucial water storage and distribution system in the region.
Overall, Greaser Lake Reservoir serves as a key infrastructure for irrigation and water management in Lake County, Oregon. Its strategic location, ample storage capacity, and low hazard potential make it an essential component in the region's water supply network. As water resource and climate enthusiasts, it is important to monitor and support the maintenance and regulation of Greaser Lake Reservoir to ensure sustainable water use and management practices for the future.
Year Completed |
1963 |
Dam Length |
505 |
Dam Height |
10 |
River Or Stream |
TWENTY MILE CREEK |
Primary Dam Type |
Earth |
Surface Area |
4000 |
Hydraulic Height |
8 |
Drainage Area |
270 |
Nid Storage |
20000 |
Structural Height |
10 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
Low |
Nid Height |
10 |
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.
Greaser Lake Reservoir