Henne
High HazardSatisfactory ConditionEmergency Action Plan: Yes
Location
| County | Napa |
| Nearest City | Angwin |
| River/Stream | Angwin Stream |
| Coordinates | 38.58650, -122.46280 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 49 ft |
| Dam Height | 49 ft |
| Dam Length | 470 ft |
| Year Completed | 1959 (67 years old) |
Storage & Hydraulics
| NID Storage | 109 acre-ft |
| Max Storage | 109 acre-ft |
| Surface Area | 9 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Howell Mountain Mutual Water Company |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/11/2025 |
| Emergency Action Plan | Yes |