Mossyrock
High HazardUnsatisfactory ConditionEmergency Action Plan: Yes
Location
| State | Washington |
| County | Lewis |
| Nearest City | Toledo, WA |
| River/Stream | Cowlitz River |
| Coordinates | 46.53460, -122.42500 |
Physical Characteristics
| Dam Type | Arch |
| NID Height | 606 ft |
| Dam Height | 366 ft |
| Dam Length | 1,750 ft |
| Year Completed | 1968 (58 years old) |
Storage & Hydraulics
| NID Storage | 1,900,000 acre-ft |
| Max Storage | 1,900,000 acre-ft |
| Normal Storage | 1,700,000 acre-ft |
| Drainage Area | 1,042 sq mi |
| Max Discharge | 280,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | City of Tacoma |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 08/20/2025 |
| Emergency Action Plan | Yes |