Lagunitas is an earth dam located in Marin County, California, built in 1872. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 48 ft48 ft tall and 433 ft long, taller than 92% 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 Lagunitas
The primary purpose of Lagunitas 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 Marin Municipal Water District (public utility). It impounds the Lagunitas Creek.
The dam stands 48 feet tall and stretches 433 feet across, creates a reservoir covering 22 acres, has a maximum storage capacity of 341 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1872, the structure is one of the older dams in the region, with over a century and a half of service.
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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 09/18/2025.
At 48 feet, this dam is taller than 92% of dams nationwide.
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Location
| State | California |
| County | Marin |
| River/Stream | Lagunitas Creek |
| Coordinates | 37.94760, -122.59630 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 48 ft |
| Dam Height | 48 ft |
| Dam Length | 433 ft |
| Year Completed | 1872 (154 years old) |
Storage & Hydraulics
| NID Storage | 341 acre-ft |
| Max Storage | 341 acre-ft |
| Surface Area | 22 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Marin Municipal Water District |
| Owner Type | Public Utility |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/18/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00205 |
| Federal ID | CA00205 |
| More Info | State Dam Safety Program |