Best Practices for Emergency Action Plans (EAPs) on Significant- and High-Hazard Dams

Straightforward guidance to help dam owners protect the people who live and work downstream

 

What Is an Emergency Action Plan?

If you’ve ever stood near a dam, it’s easy to forget what that structure is holding back. Most days, it looks calm and predictable. But every dam carries a real hazard: if something goes wrong, the sudden release of water can put downstream communities at risk in minutes.

An Emergency Action Plan — or EAP — is a plan that dam owners put together long before anything goes wrong. It lays out, step by step, what needs to happen if the dam shows signs of distress or actually fails. The entire purpose is simple: protect life, warn people quickly, and help emergency responders act without hesitation.

EAPs are usually required for high-hazard and significant-hazard dams, but the value of a good EAP goes well beyond checking a regulatory box. It makes the difference between aimless scrambling during a crisis and having everyone already know their role to effectively save lives and protect downstream properties.

 

What Is the Purpose of an Emergency Action Plan?

An EAP is designed to answer the urgent questions: If the dam could fail, who needs to know, and what steps are needed to protect downstream lives and property?

All of the plan elements — maps, breach models, call lists, warning messages — support that mission. A good plan gives emergency responders clear, fast, and actionable information. It gives downstream residents a chance to get out of harm’s way. And it gives dam owners confidence that they’re prepared for a situation nobody ever wants to face.

 

Why Should You Have an Emergency Action Plan?

Most dam owners are optimistic about their structures — and many of them have good reason to be. But dams age. Rainfall patterns change. Development increases downstream. And in nearly every case where disaster struck, the story afterward sounded the same:

“We didn’t think it would happen to us.”

Without a current EAP:

• Emergency responders won’t have accurate information
• Downstream residents may not get warnings in time
• Potential damage may increase dramatically
• Dam owners could face increased legal and financial exposure

When something goes wrong at a dam, everyone immediately discovers whether the EAP was kept current or left to gather dust. A plan that’s been maintained and updated is the one that actually protects people when minutes matter.

 

Low-, Significant-, and High-Hazard Dams: What the Classification Actually Means

Hazard classification is one of the most misunderstood terms in dam safety. It does not describe the condition of the dam itself. It simply characterizes the potential consequences of failure based on what is located downstream of the dam.

In the State of Texas, a dam is classified as high hazard if failure could result in loss of seven or more lives, three or more houses, or excessive economic loss.  A dam is classified as a significant hazard if failure could result in loss of one to six lives, one or two habitable structures, or appreciable economic loss.

The hazard classification doesn’t describe the dam’s condition — it describes the consequences of failure. A small, well-built dam near an urban neighborhood could be a high-hazard structure, while a larger dam in an undeveloped, rural valley could be a low-hazard structure.

 

What Goes Into an Effective EAP?

A good EAP blends solid engineering with clear, practical guidance. It starts with reliable breach modeling, identifies downstream vulnerabilities, lays out who needs to be notified and when, and provides the maps, contacts, and procedures that let responders act quickly.

1. Breach Simulations

Using tools like HEC-RAS 2D, engineers model three key scenarios:

• Sunny-day breach: (normal water level, no precipitation)
• Barely-overtopping event: (water just begins spilling over the crest of the dam— especially dangerous for earthen dams)
• Design-flood breach: A breach modeled under peak conditions of the dam’s required design storm — essentially the “worst-case” flooding scenario defined by state regulations.

The breach model results illustrate the extent of flooding: where the water goes, how high it rises, and how quickly it reaches downstream areas. Those details can drive the notification timeline, especially for dams with longer inundation zones.

2. Inundation Mapping

These maps make the EAP effective. They show:

• Potential flood areas downstream
• Arrival times of the flood peak
• Critical crossings and structures
• Suggested detour routes

Responders often rely on these maps more than anything else in the plan.

3. Notification Flow and Communication Protocols

An EAP must make it crystal clear:

• Who gets notified
• How to describe the condition of the dam
• What information responders need
• Which agencies to coordinate with

Many plans include prewritten messages to facilitate efficient communication and to avoid confusion during an actual emergency.

4. Contact Lists

One of the simplest — and most commonly neglected — parts of an EAP.

Every relevant responder and downstream stakeholder must be included in the plan’s contact list. Outdated contact information or missing agencies can cripple an otherwise solid EAP.

5. Resources and Equipment

This often includes:

• Locations of sand, gravel, and other emergency repair materials
• Barriers or temporary dams
• Equipment that might help with emergency repairs and water diversion

6. Plan Distribution

Copies should go to:

• Emergency operations centers
• Local fire and police departments
• State dam safety regulators
• Anyone else who needs it during an emergency

 

Implementing and Maintaining the Plan

Creating an EAP is not the end of the job — it’s the start of a long-term safety process.

How Often Should It Be Updated?

Most states require a full review every five years, but the plan should be updated any time:

• Downstream development changes
• Contact information becomes outdated
• Dam modifications are made
• New data or modeling tools become available

The Role of Tabletop Exercises

Tabletop exercises are simulations where the owner and emergency officials pretend that a dam emergency is occurring and work through the process of executing the EAP procedures. A tabletop exercise turns the EAP from a binder of theories into a real plan that becomes etched in the minds of its users. These sessions also provide opportunities for improvement, often revealing outdated contacts, unclear procedures, or missing resources — the kinds of issues you don’t want to discover during an actual emergency.

 

What Separates Good EAPs from “Check-the-Box” Plans

Givler Engineering has reviewed numerous EAPs over the years. The ones that fail to measure up typically have the same issues:

• Old or missing maps
• Outdated contact lists
• No breach modeling
• No clear notification protocols

Effective EAPs, on the other hand, are:

• Up-to-date
• Clear and easy to follow
• Based on modeled breach simulations
• Shared with the right people
• Actually tested in tabletop exercises

They’re built to function, not just to sit in a binder.

 

Advice for Dam Owners

EAPs fall off the radar because emergencies are rare — and that’s exactly why they need attention. One dam failure can define a community’s memory for decades.

A few simple habits go a long way:

• Treat contact updates as part of regular maintenance
• Keep communication open with downstream residents
• Use updates as a chance to build goodwill
• Schedule EAP reviews regularly, even if nothing seems to have changed

And above all: rely on qualified dam safety engineers to handle the technical side. Breach modeling and hydraulic analysis are not DIY tasks.

 

Conclusion

A well-prepared Emergency Action Plan can save lives. It’s that simple. High-hazard dams carry real downstream risk, and having an EAP that’s accurate, current, and ready to use is one of the most responsible things a dam owner can do.

Givler Engineering has decades of experience developing, updating, and exercising EAPs for significant-hazard and high-hazard dams across multiple states. Our goal is straightforward: create plans that work — not just plans that meet the minimum requirements.

If you need expert assistance in developing your Emergency Action Plan, contact Givler Engineering today.