Big Lagoon
Big Lagoon is an earth dam located in Humboldt County, California, built in 1947. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Big Lagoon
The primary purpose of Big Lagoon is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by California Redwood Acquisition Company (private). It impounds the Big Lagoon.
The dam stands 16 feet tall and stretches 3,700 feet across, creates a reservoir covering 78 acres, has a maximum storage capacity of 780 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1947, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 05/07/2025.
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Location
| State | California |
| County | Humboldt |
| River/Stream | Big Lagoon |
| Coordinates | 41.15590, -124.10227 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 3,700 ft |
| Year Completed | 1947 (79 years old) |
Storage & Hydraulics
| NID Storage | 780 acre-ft |
| Max Storage | 780 acre-ft |
| Surface Area | 78 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | California Redwood Acquisition Company |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/07/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CA00503 |
| Federal ID | CA00503 |
| More Info | State Dam Safety Program |