Gamache Dam Reservoir Report
Last Updated: December 12, 2025
Gamache Dam, located in Moxee, Washington, stands as a vital structure for irrigation purposes, completed in 1987 by PLSA Engineers.
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Summary
The dam's primary goal is to facilitate irrigation needs in the area, with a storage capacity of 26 acre-feet and a hydraulic height of 11 feet. Situated on an unnamed stream, the dam plays a crucial role in managing water resources for the surrounding region, with a drainage area of 2.8 square miles.
Despite its importance, Gamache Dam poses a high hazard potential, with a fair condition assessment as of March 2015. Regular inspections are conducted every five years to ensure its structural integrity and safety. Managed by a private entity, the dam falls under the regulatory oversight of the Washington Department of Ecology, showcasing the collaboration between private owners and state agencies in maintaining water infrastructure in the region.
With its earth core and stone foundation, Gamache Dam spans 650 feet in length and serves as a key component of the local water management system. As a notable feature in Yakima, Washington, the dam exemplifies the intersection of human ingenuity and environmental stewardship in safeguarding water resources for irrigation and agricultural purposes.
Year Completed |
1987 |
Dam Length |
650 |
River Or Stream |
Unnamed Stream |
Primary Dam Type |
Earth |
Hydraulic Height |
11 |
Drainage Area |
2.8 |
Nid Storage |
26 |
Structural Height |
11 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
11 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Yakima River Above Ahtanum Creek At Union Gap
|
29600cfs |
Ahtanum Creek At Union Gap
|
542cfs |
Granger Drain At Granger
|
13cfs |
Columbia River Below Priest Rapids Dam
|
103000cfs |
Yakima River At Umtanum
|
16400cfs |
Yakima River At Mabton
|
26200cfs |
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.
Gamache Dam