Davenport Sewage Lagoon No 4 Reservoir Report
Last Updated: December 15, 2025
Davenport Sewage Lagoon No 4 is a critical water resource management facility located in Davenport, Washington.
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Summary
Owned by the local government, this sewage lagoon is regulated by the Washington Department of Ecology and is permitted, inspected, and enforced to ensure compliance with state regulations. The lagoon, completed in 1987, serves as an offstream storage facility for Cottonwood Creek and has a capacity of 121 acre-feet with a normal storage level of 93 acre-feet.
With a structural height of 15 feet and a length of 2380 feet, Davenport Sewage Lagoon No 4 is classified as an earth dam with a rockfill core and soil foundation. This lagoon has a high hazard potential but is currently assessed as satisfactory in condition. Despite its high hazard potential, the facility has not been modified in recent years and is monitored through regular inspections to ensure its safety. In case of emergencies, the lagoon is expected to meet guidelines with an emergency action plan in place.
Overall, Davenport Sewage Lagoon No 4 plays a crucial role in managing wastewater in the area and is a key component of the local water infrastructure. With its strategic location and capacity, this facility helps protect the environment and public health by safely storing and treating sewage. As a well-maintained and regulated facility, it exemplifies the importance of proper water resource management in combating climate change and ensuring sustainable water use for future generations.
Year Completed |
1987 |
Dam Length |
2380 |
River Or Stream |
Cottonwood Creek-Offstream |
Primary Dam Type |
Earth |
Surface Area |
14 |
Hydraulic Height |
15 |
Drainage Area |
0.02 |
Nid Storage |
121 |
Structural Height |
15 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Chamokane Creek Below Falls Near Long Lake
|
32cfs |
Coal Creek At Mohler
|
1cfs |
Spokane River Below Nine Mile Dam At Spokane
|
17300cfs |
Little Spokane River Near Dartford
|
527cfs |
Hangman Creek At Spokane
|
98cfs |
Spokane River At Spokane
|
17500cfs |
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.
Davenport Sewage Lagoon No 4