Centralia Coal Mine Dam No 3b Reservoir Report
Last Updated: December 15, 2025
Centralia Coal Mine Dam No 3b, also known as Widco Dam No.
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Summary
3b, is a significant earth dam located in Centralia, Washington, along Tr-Hanaford Creek. Built in 1980 for the primary purpose of tailings storage, this dam stands at a hydraulic height of 140 feet with a structural height of 140 feet, stretching 1700 feet in length. The dam has a storage capacity of 860 acre-feet, with a normal storage level of 230 acre-feet, covering a surface area of 115 acres and draining a 0.5 square mile watershed.
Managed by a public utility owner type and regulated by the Washington Dept of Ecology, Centralia Coal Mine Dam No 3b is considered to have a fair condition assessment with a significant hazard potential. The dam has a history of regular inspections, with the most recent one conducted in August 2020. Despite its fair condition, the dam has not undergone any modifications over the years, and its emergency action plan (EAP) was last revised in July 2013.
Located in Congressional District 03 of Washington, Centralia Coal Mine Dam No 3b plays a crucial role in managing tailings and protecting the surrounding environment. With its strategic position and significant storage capacity, the dam serves as a key infrastructure for water resource management in the region. Enthusiasts of water resources and climate will find Centralia Coal Mine Dam No 3b to be a fascinating case study in dam engineering, regulation, and maintenance in the Pacific Northwest.
Year Completed |
1980 |
Dam Length |
1700 |
River Or Stream |
Tr-Hanaford Creek |
Primary Dam Type |
Earth |
Surface Area |
115 |
Hydraulic Height |
140 |
Drainage Area |
0.5 |
Nid Storage |
860 |
Structural Height |
140 |
Hazard Potential |
Significant |
Foundations |
Rock |
Nid Height |
140 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Tenino City Park
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Stan Hedwall Park
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Millersylvania State Park
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Millersylvania State Park Campground
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Centralia Coal Mine Dam No 3b