Olson Reservoir Report
Last Updated: December 13, 2025
Olson, Phillip 2-B is a privately owned earth dam located in Yamhill, Oregon, specifically in the city of Amity.
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Summary
Completed in 1977, this dam serves primarily for irrigation purposes, with a maximum storage capacity of 50 acre-feet and a normal storage of 50 acre-feet. The dam stands at a height of 18 feet with a hydraulic height of 14 feet and a length of 500 feet, encompassing a surface area of 8.05 acres and draining a 0.35 square mile watershed.
This low-hazard dam on Ash Swale, a tributary to an unnamed river, is regulated by the Oregon Water Resources Department and undergoes regular inspections every six years. The structure features a slide (sluice gate) outlet gate and has not been rated in terms of condition assessment. While no emergency action plan (EAP) is currently in place, the dam poses low risk according to hazard potential assessments. With its location in a picturesque rural setting, Olson, Phillip 2-B presents an intriguing case study for water resource and climate enthusiasts interested in the management and regulation of small-scale irrigation dams in Oregon.
Overall, Olson, Phillip 2-B provides a fascinating glimpse into the world of privately owned dams and the crucial role they play in supporting agricultural activities in the region. As climate change continues to impact water resources and infrastructure, understanding the maintenance and regulation of structures like Olson, Phillip 2-B is vital for ensuring the sustainability and resilience of our water systems. This dam serves as a valuable example of the intersection between human development and environmental stewardship, highlighting the ongoing challenges and opportunities in managing water resources in a changing climate.
Year Completed |
1977 |
Dam Length |
500 |
Dam Height |
18 |
River Or Stream |
ASH SWALE, TRIB TO |
Primary Dam Type |
Earth |
Surface Area |
8.05 |
Hydraulic Height |
14 |
Drainage Area |
0.35 |
Nid Storage |
50 |
Structural Height |
18 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
Low |
Nid Height |
18 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
South Yamhill River At Mcminnville
|
8310cfs |
Willamette River At Salem
|
35800cfs |
Willamette River At Newberg
|
52600cfs |
Zollner Creek Near Mt Angel
|
320cfs |
Pudding River Near Woodburn
|
4380cfs |
Abiqua Creek At Silverton
|
74cfs |
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.
Olson, Phillip 2-B
Mission Lake