Derby Diversion Reservoir Report
Last Updated: December 13, 2025
The Derby Diversion, located in Washoe County, Nevada, along the Truckee River, is a concrete arch dam completed in 1904 primarily used for irrigation purposes.
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Summary
Managed by the Bureau of Reclamation, this Federal-owned structure stands at 31 feet high and has a storage capacity of 2,500 acre-feet. With a low hazard potential and a very high risk assessment rating, the dam has not been assessed for its condition, emergency action plan, or risk management measures.
Despite its age, the Derby Diversion continues to play a crucial role in water resource management in the region. As a key feature along the Truckee River, it provides irrigation water to support agricultural activities in the area. The dam's controlled spillway type and lack of outlet gates indicate a basic design intended for water diversion and storage purposes. Although the structure's condition assessment is not available, its historical significance and continued operation underscore its importance in the local water infrastructure.
Water resource and climate enthusiasts can appreciate the Derby Diversion as a historic and functional piece of infrastructure that contributes to the agricultural landscape of Washoe County, Nevada. As a Federal-owned dam managed by the Bureau of Reclamation, its presence along the Truckee River highlights the ongoing efforts to manage and allocate water resources in the region. While the dam's risk assessment is noted as very high, further evaluation and updates to its emergency action plan and risk management measures may be necessary to ensure its continued safe operation in the face of potential hazards.
Year Completed |
1904 |
Dam Length |
1331 |
Dam Height |
31 |
River Or Stream |
TRUCKEE RIVER |
Primary Dam Type |
Concrete |
Hydraulic Height |
15 |
Nid Storage |
2500 |
Structural Height |
31 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
31 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Truckee R Bl Derby Dam Nr Wadsworth
|
289cfs |
Truckee River Nr Tracy
|
441cfs |
Truckee Ca Nr Wadsworth
|
201cfs |
Truckee R At Wadsworth
|
302cfs |
Truckee R At Vista
|
427cfs |
Truckee R Nr Nixon
|
289cfs |
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.
Derby Diversion