Map of All 835 Washington Dams
Washington has 835 dams in the National Inventory of Dams — and 416 are classified as high hazard (50% of the state’s total), meaning failure would likely cause loss of life. 52 Washington dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive Washington dams map below to explore every dam in the state, color-coded by hazard level. Click any dam for its condition assessment, last inspection date, and Emergency Action Plan status. Or view the full US Dams interactive map to compare Washington to every other state.
Hazard
Condition
Purpose
Washington Dams by the Numbers
- 835 total dams in Washington
- 416 high hazard — failure would likely cause loss of life
- 99 significant hazard
- 317 low hazard
- 68 in poor or unsatisfactory condition (63 poor, 5 unsatisfactory)
- 52 Washington dams are both high-hazard AND in poor/unsatisfactory condition
Data source: US Army Corps of Engineers, National Inventory of Dams (NID).
The Tallest Dams in Washington
The tallest dam in Washington is Mossyrock at 606 feet, completed in 1968. The 10 tallest Washington dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Mossyrock | 606 ft | 1968 | Hydroelectric | Unsatisfactory | Lewis |
| Grand Coulee Dam | 550 ft | 1941 | Flood Risk Reduction | Not Available | Okanogan |
| Ross | 540 ft | 1949 | Hydroelectric | Satisfactory | Whatcom |
| Mud Mountain Dam | 425 ft | 1948 | Flood Risk Reduction | Not Available | King |
| Swift No. 1 | 412 ft | 1958 | Hydroelectric | Fair | Skamania |
| Diablo | 389 ft | 1929 | Hydroelectric | Satisfactory | Whatcom |
| Boundary | 360 ft | 1967 | Hydroelectric | Fair | Pend Oreille |
| Asamera Cannon Mine Tailings Dam | 340 ft | 1986 | Flood Risk Reduction | Satisfactory | Chelan |
| Alder | 330 ft | 1945 | Hydroelectric | Satisfactory | Pierce |
| Yale | 323 ft | 1953 | Hydroelectric | Fair | Cowlitz |
High-Hazard Washington Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 52 dams in Washington. Notable examples:
- Mossyrock (606 ft, Lewis County) — Hydroelectric, Unsatisfactory condition
- Lower Baker (285 ft, Skagit County) — Hydroelectric, Poor condition
- Mayfield (250 ft, Lewis County) — Hydroelectric, Unsatisfactory condition
- Wells (160 ft, Chelan County) — Hydroelectric, Poor condition
- Indian Creek Dam (73 ft, Pacific County) — Water Supply, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in Washington
Dam safety in Washington is overseen by the state dam safety program, in coordination with federal regulators: the US Army Corps of Engineers, the Bureau of Reclamation (for federal water projects), the Tennessee Valley Authority where applicable, and the Federal Energy Regulatory Commission (FERC) for licensed hydropower dams. Emergency Action Plans are typically required for high-hazard dams under state regulations.
Frequently Asked Questions
How many dams are in Washington?
Washington has 835 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 416 high hazard, 99 significant hazard, and 317 low hazard.
What is the tallest dam in Washington?
The tallest dam in Washington is Mossyrock at 606 feet, completed in 1968. It is primarily a hydroelectric structure.
How many Washington dams are in poor condition?
68 Washington dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 52 are also classified as high-hazard — meaning failure would likely cause loss of life.
