Blackwelder Reservoir Report

Last Updated: December 5, 2025

Blackwelder, also known as Upper Blackwelder Lake, is a federally owned dam located in Yuba County, California.


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Summary

Built in 1955 by the USAF, this rockfill dam stands at a height of 19 feet and serves primarily for flood risk reduction. With a storage capacity of 330 acre-feet and a surface area of 35 acres, Blackwelder plays a crucial role in managing water resources in the area.

Situated on Hutchinson Creek, Blackwelder has a significant hazard potential and is classified as having a moderate risk level. Despite its age, the dam has not undergone a recent condition assessment and lacks an emergency action plan. With no outlet gates and an uncontrolled spillway, the dam poses challenges for emergency response and water release during high flow events. However, the dam's inspection frequency of every 5 years helps to ensure its structural integrity and safety.

While primarily designed for flood risk reduction, Blackwelder also offers recreational opportunities for visitors. As part of the US Air Force infrastructure, the dam is a key component of the region's water management system. Its location at Beale AFB makes it a notable landmark in the area, attracting both water resource and climate enthusiasts interested in its engineering and environmental impact.

Year Completed

1955

Dam Length

1000

Dam Height

14

River Or Stream

HUTCHINSON CREEK

Primary Dam Type

Rockfill

Surface Area

35

Hydraulic Height

14

Drainage Area

6.35

Nid Storage

330

Structural Height

19

Outlet Gates

None

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

19
       
Seasonal Comparison

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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.