Sea Ranch is an earth dam located in Sonoma County, California, built in 1996. It carries a Low hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 61 ft61 ft tall and 2,500 ft long, taller than 95% 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 Sea Ranch
The primary purpose of Sea Ranch 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 The Sea Ranch Water Company (private). It impounds the Offstream.
The dam stands 61 feet tall and stretches 2,500 feet across, creates a reservoir covering 14 acres, has a maximum storage capacity of 300 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1996, the structure is 30 years old.
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 04/22/2025.
At 61 feet, this dam is taller than 95% of all dams in the United States.
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Location
| State | California |
| County | Sonoma |
| River/Stream | Offstream |
| Coordinates | 38.76020, -123.50060 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 61 ft |
| Dam Height | 61 ft |
| Dam Length | 2,500 ft |
| Year Completed | 1996 (30 years old) |
Storage & Hydraulics
| NID Storage | 300 acre-ft |
| Max Storage | 300 acre-ft |
| Surface Area | 14 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | The Sea Ranch Water Company |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/22/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CA01411 |
| Federal ID | CA01411 |
| More Info | State Dam Safety Program |