Lower Monumental Lock And Dam
High HazardNot Available ConditionEmergency Action Plan: Yes
Location
| State | Washington |
| County | Franklin |
| Nearest City | PASCO |
| River/Stream | SNAKE RIVER |
| Coordinates | 46.56219, -118.53769 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 226 ft |
| Dam Length | 3,800 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 432,000 acre-ft |
| Max Storage | 432,000 acre-ft |
| Normal Storage | 377,000 acre-ft |
| Surface Area | 6,590 acres |
| Drainage Area | 108,500 sq mi |
| Max Discharge | 850,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - Walla Walla District |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 10/29/2025 |
| Emergency Action Plan | Yes |