Chapman Lake Dam Reservoir Report
Last Updated: December 13, 2025
Chapman Lake Dam, located in Spokane, Washington, was completed in 1940 and serves primarily for recreational purposes.
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Summary
The dam, a gravity type structure with a hydraulic height of 18 feet and a structural height of 17 feet, impounds Rock Creek to create a reservoir with a maximum storage capacity of 8,000 acre-feet. The dam has a normal storage capacity of 7,500 acre-feet and covers a surface area of 150 acres, with a drainage area of 48.5 square miles.
Although Chapman Lake Dam is privately owned, it is regulated by the Washington Department of Ecology and undergoes regular inspections. The dam has a low hazard potential and has not been rated for its condition assessment. The last inspection took place in October 1993, with an inspection frequency of 0, indicating a need for more regular assessments. Despite the lack of recent condition assessments, the dam continues to provide recreational opportunities for visitors to enjoy the scenic beauty of Chapman Lake.
Water resource and climate enthusiasts interested in Chapman Lake Dam can appreciate its historical significance as a gravity dam that has been part of the Spokane landscape for over 80 years. The dam's association with Rock Creek and its role in creating a reservoir for recreational activities highlight the importance of sustainable water management practices in maintaining the ecological balance of the area. As efforts continue to ensure the safety and integrity of Chapman Lake Dam, it remains a vital part of the local ecosystem and a source of enjoyment for outdoor enthusiasts in Washington state.
Year Completed |
1940 |
Dam Length |
75 |
River Or Stream |
Rock Creek |
Primary Dam Type |
Gravity |
Surface Area |
150 |
Hydraulic Height |
18 |
Drainage Area |
48.5 |
Nid Storage |
8000 |
Structural Height |
17 |
Hazard Potential |
Low |
Foundations |
Rock, Soil |
Nid Height |
18 |
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.
Chapman Lake Dam