Rosalia Sewage Lagoon Reservoir Report
Last Updated: December 16, 2025
Located in Whitman County, Washington, the Rosalia Sewage Lagoon is a vital water resource managed by the local government.
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Summary
This sewage lagoon, completed in 1989, serves a critical role in wastewater treatment and is regulated by the Washington Department of Ecology. With a maximum storage capacity of 37 acre-feet and a surface area of 4.79 acres, the lagoon plays a crucial role in managing the area's drainage and wastewater disposal needs.
Despite its high hazard potential, the Rosalia Sewage Lagoon is assessed to be in fair condition as of its last inspection in September 2018. Regular inspections are conducted every five years to ensure the lagoon's structural integrity and safety measures are up to standard. Additionally, emergency action plans and risk management measures are in place to address any potential threats or incidents that may arise. The lagoon's proximity to Congressional District 05, represented by Cathy McMorris Rodgers, highlights its importance in water resource management and environmental stewardship.
Overall, the Rosalia Sewage Lagoon stands as a crucial infrastructure asset in the region, providing essential wastewater treatment services while adhering to state regulations and enforcement. Water resource and climate enthusiasts can appreciate the lagoon's role in safeguarding water quality and protecting the environment, making it a key player in sustainable water management efforts in Whitman County, Washington.
Year Completed |
1989 |
Primary Dam Type |
Earth |
Surface Area |
4.79 |
Hydraulic Height |
10 |
Drainage Area |
0.01 |
Nid Storage |
37 |
Structural Height |
10 |
Hazard Potential |
High |
Nid Height |
10 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Hangman Creek At State Line Road Near Tekoa
|
25cfs |
Hangman Creek At Spokane
|
126cfs |
Spokane River At Spokane
|
18800cfs |
Palouse River Nr Potlatch Id
|
225cfs |
St Joe River Nr Chatcolet Id
|
802cfs |
St Joe River At Ramsdell Nr St Maries Id
|
8190cfs |
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.
Rosalia Sewage Lagoon