Lower Monumental Lock and Dam
Washington — Franklin County — SNAKE RIVER
Location
| State | Washington |
| County | Franklin |
| River | SNAKE RIVER |
| Coordinates | 46.56219, -118.53769 |
Physical Characteristics
| NID Height | 226 ft |
| Dam Height | — |
| Dam Length | 3,800 ft |
| NID Storage | 432,000 acre-ft |
| Max Storage | 432,000 acre-ft |
| Surface Area | 6,590 acres |
Safety Classification
| Hazard Potential | High |
| Condition Assessment | Not Available |
| EAP Status | Yes |
| Last Inspection | October 29, 2025 |
| Inspection Frequency | 5 |
Dam Information
| Year Completed | 1969 |
| Primary Purpose | Navigation |
| Dam Type | Concrete |
| Owner Type | Federal |
| Owner | USACE - Walla Walla District |
| Other Name | Lake Herbert G. West |
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.