Lower Blackwelder Dam is a rockfill dam located in Yuba County, California, built in 1955. It carries a Significant hazard potential classification.
Dam profile
NID height · 15 ft15 ft tall and 700 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic rockfill embankment section and the water level is illustrative.
About Lower Blackwelder Dam
The primary purpose of Lower Blackwelder Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Usaf Acc (federal). It impounds the Hutchinson Creek near Beale Afb.
The dam stands 15 feet tall and stretches 700 feet across, creates a reservoir covering 20 acres, has a maximum storage capacity of 160 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1955, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. The most recent inspection on record was 07/18/2022.
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Location
| State | California |
| County | Yuba |
| Nearest City | Beale Afb |
| River/Stream | Hutchinson Creek |
| Coordinates | 39.13500, -121.38333 |
Physical Characteristics
| Dam Type | Rockfill |
| NID Height | 15 ft |
| Dam Height | 10 ft |
| Dam Length | 700 ft |
| Year Completed | 1955 (71 years old) |
Storage & Hydraulics
| NID Storage | 160 acre-ft |
| Max Storage | 160 acre-ft |
| Normal Storage | 20 acre-ft |
| Surface Area | 20 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 482 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Usaf Acc |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 07/18/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | CA10118 |
| Federal ID | CA10118 |
| More Info | State Dam Safety Program |