Flood Myths

Since we recently had a 100-year flood, I will be safe from flooding for another 100 years.

False! The term "100-year flood" describes the potential magnitude of a flood, not a time period. A 100-year flood is a severe event that statistically has a 1 out of 100 (or one percent) chance of being equaled or exceeded on a specific watercourse in any given year. Although it is a rare event over the course of one year, a flood of this size can occur numerous times during a 100-year period.

If my house or property was not flooded in the last flood, then it is not in a floodplain and I don't need to be concerned about flooding.

False! A floodplain is the land area susceptible to being inundated by flood waters from any source. Some floods will cover only part of a floodplain, while more severe floods will inundate the entire floodplain. The Flood Control District can tell you if your home or property is located in a FEMA Special Flood Hazard Area (SFHA).

If I build my home outside a FEMA Special Flood Hazard Area, I will never have any flood damages.

False! Flooding can occur in virtually any location, depending on many factors such as weather conditions, soil types and topography. A FEMA Special Flood Hazard Area is simply a documented area that has the potential for flooding. Since nearly 20% of claims come from outside the FEMA SFHA, Mohave County Flood Control District encourages everyone to purchase flood insurance.

If it is not raining in my neighborhood, there won’t be any water in the wash behind my house.  

False! A single wash is interconnected in a natural drainage system that includes other washes and rivers. Heavy rainfall miles away can build up in another wash in the system, sending a torrent of water down the wash by your house in just a matter of minutes. This is a dangerous situation called a flash flood.

Placing plywood, branches, or landscape refuse in the embankment of a wash is an effective method of flood protection.

False! Floodwater rushing through a wash in a flash flood situation has incredible power. One cubic foot of water weighs 62.4 pounds and a wash can flow at the rate of hundreds or thousands of cubic feet per second.

If a dip in a roadway looks like it has only six or eight inches of water running over it, then it is safe for me to drive across.

False! It is never safe to drive across a flooded wash. Just two feet of water can cause a vehicle to float. In addition, there could be damage to the roadway or other debris hidden under the water that cannot be seen.

I can make any drainage improvement I need to on my own private land.

False! ARS 48-3613 states "a person shall not engage in any development which will divert, retard or obstruct the flow of waters in any watercourse without securing written authorization from the board of the district in which the watercourse is located. Where the watercourse is delineated in a floodplain, no development shall take place in the floodplain without written authorization from the board of the district in which the floodplain is located." Before any improvements can be made, even on private land, you must first determine if your land is within a FEMA Special Flood Hazard Area.