Cow Lake Dam Reservoir Report
Last Updated: December 13, 2025
Cow Lake Dam, also known as Harder Dam, is a private-owned structure located in Adams County, Washington.
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Summary
Completed in 1935, this earth and gravity dam serves primarily for recreation purposes, with irrigation as a secondary function. Situated on Cow Creek, the dam has a hydraulic height of 7 feet and a structural height of 4 feet, with a length of 600 feet and a storage capacity of 900 acre-feet.
The dam has a low hazard potential and is not currently rated for its condition. Despite not being federally owned or funded, the Washington Department of Ecology regulates, inspects, and enforces state jurisdiction over the dam. With a maximum discharge capacity of 95 cubic feet per second and a surface area of 240 acres, Cow Lake Dam plays a crucial role in water resource management in the region.
Even though the dam's emergency action plan status and risk assessment information are not provided, its importance in supporting local irrigation and recreational activities cannot be understated. Its location within the Seattle District and Congressional District 04, under Representative Dan Newhouse, highlights the significance of Cow Lake Dam in the overall water resource and climate management efforts in Washington State.
Year Completed |
1935 |
Dam Length |
600 |
River Or Stream |
Cow Creek |
Primary Dam Type |
Earth |
Surface Area |
240 |
Hydraulic Height |
7 |
Drainage Area |
315 |
Nid Storage |
900 |
Structural Height |
4 |
Hazard Potential |
Low |
Foundations |
Rock, Soil |
Nid Height |
7 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Coal Creek At Mohler
|
1cfs |
Palouse River At Hooper
|
574cfs |
Crab Creek At Irby
|
2cfs |
Tucannon River Near Starbuck
|
192cfs |
Hangman Creek At Spokane
|
102cfs |
Spokane River At Spokane
|
14500cfs |
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.
Cow Lake Dam