Summary
Built in 1910, this Earth-type dam stands at 31.3 feet high and has a storage capacity of 9,583 acre-feet, serving various purposes beyond flood control and water supply. Despite its age, the dam has faced concerns over its high hazard potential and poor condition assessment, prompting regular inspections and enforcement measures by the Idaho Department of Water Resources.
The dam's hydraulic height of 23.1 feet and controlled spillway with a width of 21 feet indicate its capacity to manage maximum discharges of up to 505 cubic feet per second. However, its poor condition assessment and high hazard potential suggest a need for improved risk management measures to ensure the safety of surrounding communities. The dam's location within the Walla Walla District and its association with the Weiser River make it a critical water resource and climate focal point for enthusiasts and stakeholders in the region.
Lost Valley's historical significance, coupled with its current risk assessment as very high, highlights the importance of ongoing monitoring and maintenance efforts to prevent potential disasters. As climate change continues to affect water resources and infrastructure resilience, this dam serves as a reminder of the critical role that proactive management plays in safeguarding communities and ecosystems against the impacts of extreme weather events and changing hydrological conditions.
Year Completed |
1910 |
Dam Length |
262 |
Dam Height |
31.3 |
River Or Stream |
LOST CREEK WEISER RIVER |
Surface Area |
633 |
Hydraulic Height |
23.1 |
Drainage Area |
29.3 |
Nid Storage |
9583 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
High |
Foundations |
Rock, Soil |
Nid Height |
31 |
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 |
|---|---|---|
Lost Valley Reservoir Dispersed Camping Area
|
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Slaughter Gulch
|
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Cold Springs Group Campground
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Evergreen Campground
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Evergreen
|
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Lafferty
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Lost Valley