Vonsen
High HazardSatisfactory ConditionEmergency Action Plan: Yes
Location
| County | Marin |
| Nearest City | San Antonio |
| River/Stream | Tr San Antonio Cr |
| Coordinates | 38.18210, -122.67860 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 402 ft |
| Year Completed | 1951 (75 years old) |
Storage & Hydraulics
| NID Storage | 70 acre-ft |
| Max Storage | 70 acre-ft |
| Surface Area | 9 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Mary Volpi |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 12/11/2025 |
| Emergency Action Plan | Yes |