Your Local Risks · Hazard Guide
More than 90,000 dams exist in the United States. Thousands are classified as high-hazard. Knowing whether you live downstream — and where to go if one fails — is the preparation that matters most.
Understanding the hazard
A dam failure is an uncontrolled release of the water stored behind a dam — a sudden flood that can be significantly more powerful than a natural river flood because it carries the entire stored volume at once. The resulting wave can travel faster and farther than most people expect, carrying debris and depositing sediment miles downstream.
Dams fail for several reasons: overtopping during extreme rainfall or snowmelt, structural deterioration from age or poor maintenance, seismic damage, or upstream dam failure causing cascading effects. The 2017 Oroville Dam spillway failure in California — where 188,000 people were evacuated — demonstrated that even large, federally supervised dams can experience serious structural failures.
The key risk factor is your location relative to the dam. If you live downstream, dam failure is a hazard worth understanding specifically. If you don't, the relevant flood preparedness content is at the general flood page.
Know your position
Your risk from dam failure is almost entirely determined by geography — specifically, whether your home is in the inundation zone of an upstream dam. These are the steps to find out.
01
The U.S. Army Corps of Engineers maintains a publicly searchable database of all significant dams in the U.S., including their hazard classification (low, significant, high). Search for dams near your address at the NID website.
National Inventory of Dams →02
Your state dam safety program can provide inundation maps showing the area that would be flooded if a specific dam fails. Many states publish these publicly. Contact your state emergency management agency to request maps for dams upstream of your location.
03
High-hazard dams are required to have an Emergency Action Plan (EAP) that includes downstream notification procedures. Ask your county emergency management office whether you are in a dam EAP notification zone and how you would receive a warning.
Before it happens
If you live downstream of a high-hazard dam, your preparation centers on evacuation speed — not supply stockpiling. The flood from a dam failure can arrive in minutes, not hours.
Map at least two routes to high ground from your home that do not require crossing the river or floodplain downstream of the dam. Drive them. Know which bridges might be impassable during a flood and what your alternative is if the primary route is blocked.
Register for your county's emergency notification system — most counties offer text, email, and phone alerts. Dam failure warnings may come with very little lead time. Wireless Emergency Alerts (WEA) on your cell phone and a NOAA weather radio are your most reliable backup notification systems.
A dam failure gives you minutes, not hours, to leave. A pre-packed go-bag with documents, medications, three days of supplies, and clothing means you don't spend time in a crisis deciding what to grab. Keep it accessible — not packed away in a closet.
Go-bag guide →If a dam warning is issued during the workday, your household members may be in different locations. Establish an out-of-area contact and a meeting point on high ground that everyone knows. Practice it so it's automatic.
When it happens
When a dam failure warning is issued, the flood may already be in motion. Every minute of hesitation reduces your margin. Leave now. Take your go-bag. Move to high ground via your pre-planned route.
Six inches of fast-moving water can knock a person down. Twelve inches can sweep away a vehicle. If your evacuation route requires crossing water, use your alternate route. If both are blocked, move to the highest point available and call for help.
Climb to the highest point available — a second story, a rooftop, a hill. Signal for help. Do not try to swim through fast-moving flood debris; the water from a dam failure carries significant debris load. Stay elevated and wait for emergency responders.
After the event
Do not return to a flooded area until official clearance is given. Floodwaters from dam failures carry sediment, debris, and hazardous materials that make structures unsafe and water undrinkable. Follow the same protocols as any major flood event for food, water safety, and structural inspection.
See also: Flood recovery guidance →
Your foundation
A go-bag, a family communication plan, and three days of supplies are the foundation of dam failure preparedness. The First 72 Hours guide walks you through building all three in a weekend.
Build your go-bag