Big Rock Ranch
California — Marin County — Nicasio Creek Trib To Lagunitas Creek
Location
| State | California |
| County | Marin |
| River | Nicasio Creek Trib To Lagunitas Creek |
| Coordinates | 38.05060, -122.62770 |
Physical Characteristics
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 490 ft |
| NID Storage | 91 acre-ft |
| Max Storage | 91 acre-ft |
| Surface Area | 7 acres |
Safety Classification
| Hazard Potential | High |
| Condition Assessment | Satisfactory |
| EAP Status | Yes |
| Last Inspection | December 17, 2025 |
| Inspection Frequency | 1 |
Dam Information
| Year Completed | 2002 |
| Primary Purpose | Water Supply |
| Dam Type | Earth |
| Owner Type | Private |
| Owner | Lucasfilm, LTD |
Location Map
About This Dam Record
Dam safety data is maintained by the Army Corps of Engineers National Inventory of Dams (NID). High-hazard dams are those where failure could cause loss of life or major property damage downstream.