Historical incidents & failures
Despite our best efforts to promote dam safety and assist owners in maintaining their dams in a safe manner, incidents and failures sometimes occur.
Why dams fail
Nationally, the main reasons that dams fail are:
- Overtopping — 34 percent of all failures
- Inadequate spillway design
- Debris blocking the spillway
- Settlement of dam crest
- Foundation defects — 30 percent of all failures
- Differential settlement
- Sliding and slope instability
- High uplift pressures
- Uncontrolled foundation seepage
- Piping and seepage — 20 percent of all failures
- Internal erosion through the dam caused by seepage — "piping"
- Seepage and erosion along hydraulic structures, such as an outlet
- Conduits or spillways, or leakage through animal burrows
- Cracks in the dam
- Conduits and valves — 10 percent of all failures
- Piping of embankment material into conduit through joints or cracks
- Other — 6 percent of all failures
Dam failures in Washington
Some incidents can lead to a catastrophic release of water which may cause loss of life, damage to property, and environmental harm. We refer to these events as failures. Below is a list of notable failures and some details on recent events.
Ongoing incidents
If conditions at a dam under our jurisdiction prompt an emergency declaration or the involvement of local/state emergency response staff, we track it here. This does not necessarily mean that a failure is imminent. In these cases, we work with local emergency management and the dam owner to take steps to reduce the risks posed by the dam.
Contact information
Samantha Long, EIT
Dam Safety Office Manager
samantha.long@ecy.wa.gov
Office: 360-407-6603
Cell: 360-972-4426