Onion Dam is an earth dam located in Humboldt County, Nevada. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 54 ft54 ft tall and 320 ft long, taller than 94% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic embankment section and the water level is illustrative.
About Onion Dam
The primary purpose of Onion Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Alder Creek Ranch LLC (private). It impounds the East Fork Alder Creek.
The dam stands 54 feet tall and stretches 320 feet across, creates a reservoir covering 101 acres, has a maximum storage capacity of 1,500 acre-feet, and collects water from a drainage area of 0 square miles.
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. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 07/18/2022.
At 54 feet, this dam is taller than 94% of dams nationwide.
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Location
| State | Nevada |
| County | Humboldt |
| Nearest City | None |
| River/Stream | East Fork Alder Creek |
| Coordinates | 41.69810, -118.74040 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 54 ft |
| Dam Height | 48 ft |
| Dam Length | 320 ft |
Storage & Hydraulics
| NID Storage | 1,500 acre-ft |
| Max Storage | 1,500 acre-ft |
| Normal Storage | 1,500 acre-ft |
| Surface Area | 101 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 3,700 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Alder Creek Ranch LLC |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 07/18/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NV00005 |
| Federal ID | NV00005 |
| More Info | State Dam Safety Program |