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Floodplain Management

FEMA Floodplain Maps- EFFECTIVE June 18, 2007

General Floodplain Information                                                                                                                        

How can it be determined if a home is in the floodplain?

Floodplain maps are a product of the Federal Emergency Management Agency (FEMA) and copies of these maps can be found on their website www.fema.gov. Additional information can be obtained by contacting you local floodplain administrator in the city in which you live or, for unincorporated Harris County, at the Harris County Permits office. While the maps will show your property's relationship to the flood plain, you should also consider hiring a surveyor to determine the elevation of your home relative to the Base Flood (100-year) elevation. This information is useful in determining a property's risk of flooding and in determining flood insurance requirements and rates.

What to Do if the New Floodplain Maps Do Not Identify Increased Risk for Your Property

Consider the facts: Tropical Storm Allison dropped up to 35 inches of rain in some part of Harris County, with 28 of those inches falling in 12 hours. As a result, approximately two-thirds of the areas that flooded were outside the 1% (100-year) floodplain. That is a floodplain occurring from rainfall that has 1% chance of being equaled or exceeded in any given year, as depicted on the FIRM (or floodplain) map. Additionally, approximately 64,000 property owners who did not carry flood insurance during Tropical Storm Allison experienced flooding.

Put simply, even if you have never flooded before or the new floodplain maps do not identify you as being at a high risk, it is strongly recommended that you purchase flood insurance.

What is a floodplain?

FEMA defines a floodplain as "Any land area that is susceptible to being inundated by water from any source." In Harris County, a floodplain is generally defined as an area flooded due to either a channel's capacity being exceeded or due to a tidal storm surge.

The FEMA Flood Insurance Rate Maps show my house is outside of the flood zone - do I really need flood insurance?

Everyone needs flood insurance! Just because your home is not mapped within the 100-year flood plain does not mean that you are free from the potential to flood. FEMA Flood Insurance Rate Maps (FIRMs) show areas subject to flooding from a primary flooding source, typically major rivers, bayous and their tributaries, and are meant to help determine the risk of flooding for a property. However, flooding from sources that are not identified on the FIRMs is possible and occurs often in Harris County. Many homes flood because excess storm water cannot drain into a storm drainage system fast enough to prevent localized ponding from reaching the inside of a home. On a national basis, one-third of the flood loss claims are from property located outside of the mapped 1% (100-year) flood plain. To learn how to purchase a flood insurance policy, visit the National Flood Insurance Website, www.fema.gov/nfip/ or contact your insurance agent. You may also click here for more information within this website about flood insurance.

If new floodplain maps are being developed now, are the old maps wrong?

FEMA Flood Insurance Rate Maps are estimates. The existing maps use technology that was current at the time in which those maps were developed. The new maps are using

You are encouraged to visit one of the following web sites

Tropical Storm Allison Recovery Project (TSARP)

TSARP Information sheet- How to Use the FEMA Website

16225 Park Ten Place, Suite 420
Houston, Texas 77084
(281) 579-4656

Federal Emergency Management Agency (FEMA)

500 C Street, SW
Washington, DC 20472

Harris County Flood Control District

9900 Northwest Freeway
Houston, Texas 77092