Bosma Dam No. 1 Reservoir Report
Last Updated: December 13, 2025
Bosma Dam No.
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Summary
1, located in Yakima, Washington, is a privately owned offstream earth dam with a hydraulic height of 9 feet. Completed in 2000, this dam serves a primary purpose that falls under the category of "Other," with a storage capacity of 20 acre-feet. Although it is not associated with any federal agencies, it is regulated by the Washington Department of Ecology and undergoes regular inspections to ensure its structural integrity.
With a surface area of 2.9 acres and a normal storage capacity of 16 acre-feet, Bosma Dam No. 1 poses a significant hazard potential and has been assessed to be in fair condition as of the last inspection in October 2015. The dam has a history of compliance with state regulations, including permitting, inspection, and enforcement measures. While no specific spillway type is mentioned, the dam's design includes a stone core and soil foundation, contributing to its overall stability.
In the event of an emergency, the dam's emergency action plan (EAP) status is unclear, as details regarding its preparation, last revision date, and adherence to guidelines are not provided. Despite this, the dam's risk management measures and inundation maps are not explicitly addressed in the available data. As water resource and climate enthusiasts, monitoring the condition and safety of dams like Bosma Dam No. 1 is crucial to ensuring the protection of local communities and the environment from potential hazards.
Year Completed |
2000 |
River Or Stream |
Offstream |
Primary Dam Type |
Earth |
Surface Area |
2.9 |
Hydraulic Height |
9 |
Nid Storage |
20 |
Structural Height |
9 |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
9 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Granger Drain At Granger
|
13cfs |
Yakima River At Mabton
|
26200cfs |
Yakima River Above Ahtanum Creek At Union Gap
|
29600cfs |
Ahtanum Creek At Union Gap
|
542cfs |
Columbia River Below Priest Rapids Dam
|
103000cfs |
Toppenish Creek Near Fort Simcoe
|
73cfs |
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.
Bosma Dam No. 1