Lower Blackwelder Reservoir Report

Last Updated: December 5, 2025

Lower Blackwelder, also known as Lower Blackwelder Lake, is a federal-owned dam situated in Yuba County, California, near the city of Beale AFB.


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Summary

Managed by the US Air Force, this dam primarily serves the purpose of flood risk reduction while also providing recreational opportunities. The dam is a rockfill type with a height of 10 feet and a length of 700 feet, offering a storage capacity of 160 acre-feet and covering a surface area of 20 acres.

Located on Hutchinson Creek, Lower Blackwelder has a low hazard potential and a moderate risk assessment rating. Despite its age and limited data on condition assessment, the dam is inspected every 5 years to ensure its structural integrity and overall safety. While the dam does not have an Emergency Action Plan (EAP) in place, it meets regulatory guidelines and is equipped with an uncontrolled spillway with a width of 35 feet to manage potential overflow. Overall, Lower Blackwelder plays a crucial role in flood risk management in the area, showcasing the importance of water resource infrastructure in mitigating climate-related risks.

Dam Length

700

Dam Height

10

River Or Stream

HUTCHINSON CREEK

Primary Dam Type

Rockfill

Surface Area

20

Hydraulic Height

10

Drainage Area

0.22

Nid Storage

160

Structural Height

15

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

15
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.