Surfing the waves of inundation mapping regulations

Posted in: Energy, Water


California’s emergent inundation mapping requirementsHow can you plan ahead while adrift in a sea of shifting regulations? Let me share a technique for surfing California’s emergent inundation mapping requirements.

Regulatory emergency

In the wake of the 2017 Oroville Dam spillways incident, the California Water Code now requires owners of dams not classified as ‘low hazard’ to prepare an emergency action plan. Emergency action plans include inundation maps showing the area potentially flooded by a dam failure.

To meet the timeline for code compliance, the Department of Water Resources developed emergency regulations with criteria for dam owners to prepare and submit inundation maps. DWR is currently developing the final regulations. In the meantime, many dam owners are working to understand the new requirements and wondering what might change in the final regulations.

Focus on public safety

It is our charge as civil engineers to ask ourselves at each juncture how a particular decision will affect public safety. This process will more likely lead to decisions that will reflect well in hindsight, no matter what the future holds.

Many decisions are made for us by the regulations, but there is always room for good engineering judgment. For example:

  • Are your assumed breach parameters appropriately reasonable and conservative?
  • Does your map scale represent the downstream hazard in enough detail without resulting in an unwieldy number of map sheets?

Questions like these may be difficult to answer for any given dam, let alone for all dams in the state. But if we keep public safety in focus, then we will not stray far from the spirit or letter of the law – future regulations included.

Dam owner perspective

The desire to be prepared for every “what-if” scenario needs to be tempered with an understanding of what dam owners face. While keeping within the limitations of the regulations, we begin every study at the intersection of common sense and cost savings.

Without sacrificing public safety, there are ways we can provide the information needed to prepare for an emergency without increasing the already-heavy burden of regulatory compliance. There are methods to reduce the volume of information produced. Some of the data can be provided in a more ‘raw’ format and still be just as informative. And we can be conscientious to leverage existing data where possible to provide a high-quality deliverable at a lower cost.

Enjoy the ride

Let’s be honest, it can be difficult to ‘enjoy’ regulatory compliance. Even more so when you feel like you are aiming for a moving target. But there are many aspects of this work that I do find enjoyable. In my experience dam owners are great people to work with. The process of taking facility drawings, elevation data, and more, and then making a map that is instrumental in emergency planning is very satisfying. And I hope that dam owners also find satisfaction in knowing that their regulatory compliance efforts serve the higher purpose of public safety via emergency preparedness.

So whatever changes come, be they ripples or waves, let’s enjoy the ride together!


Ryan Greif, PE

About the Author

Ryan Greif, P.E., is a water resources engineer who specializes in hydraulic analysis and design, flood risk reduction, and dam safety, working on projects involving FEMA flood mapping, dam and levee breach simulation, and large-scale irrigation distribution. He applies engineering principles from a fresh perspective to produce environmentally and financially sound solutions.

Read more posts by Ryan Greif, PE

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