How a Floodplain is Identified
Floodplain Delineation Studies identify land areas (floodplains) subject to inundation by a flood that has a one-percent probability of being equaled or exceeded in any given year, also known as a 100-year flood. The results of a Floodplain Delineation Study are submitted to the Federal Emergency Management Agency (FEMA) in order for the study to be incorporated onto the Flood Insurance Rate Maps (FIRM).
Any development in an area that is determined to be a floodplain must meet the requirements of local, state and federal regulations. One of these requirements is to build the structure so the lowest floor is above the base flood elevation. The Base Flood Elevation (BFE) is the predicted highest flood water elevation expected to occur at a location during a 100-year flood. New habitable construction must be built above the BFE, habitable means floors with living areas on them.
It is important to understand that floodplains and flood hazards exist in areas that have not yet been documented by a Floodplain Delineation Study. Although your property may not have been in a floodplain when you moved in, that could change in the future. Your area may not have been studied yet, or the floodplain limits might be modified because of changes that occurred during flooding events, or development in the area caused some change. Also, the District may use new technology that it believes will result in a more accurate identification of the floodplain limits.
Flood Hazard Information
Fill out the Flood Hazard Information Request Form. A District representative will complete a Flood Hazard - Flood Insurance Rate MAP (FIRM) Information form with the zone and map information and email or fax it back to you. There is no fee for floodplain determinations from the Flood Control District.
Your lending institution will use the Flood Insurance Rate Map (FIRM) adopted by the Federal Emergency Management Agency (FEMA) to determine whether your property is within a 100-year floodplain. If the lender makes such a determination, you are required to purchase flood insurance. The lender's floodplain determination simply locates your property in or out of the floodplain; the lender does not evaluate the property's elevation above the flood level.
Flood Hazard Determination Review
If you disagree with the lender's determination that your property is within a floodplain, you may request a Flood Hazard Determination Review by FEMA, in which case FEMA will review the information the lender used and issue a letter that states whether or not they agree with the lender's determination. Your request to FEMA must be postmarked no later than 45 days after the lender notifies you of the flood insurance requirement and the request must include all of the information and fees required by FEMA.
Letter of Map Amendment
You can also apply to FEMA for a Letter of Map Amendment (LOMA), which includes submitting an elevation certificate.
If your lot or building site is on natural ground that is higher than the Base Flood Elevation (BFE) shown on the Flood Insurance Rate Map, you may request a Letter of Map Amendment. If approved, the LOMA verifies that your building (or portions of your property) has been removed from a designated floodplain. Your lender may then choose to not require flood insurance.
To get assistance with any of these issues, please call the Floodplain Management and Services Division of the Flood Control District at 602-506-2419 and ask to speak with a floodplain representative.
A Flood Insurance Rate Map (FIRM) is the official map of a community on which the Federal Emergency Management Agency(FEMA) has delineated both the Special Flood Hazard Areas and the flood risk premium zones. Communities are mapped by their respective flood control agencies or the U.S. Army Corps of Engineers. The Flood Control District is responsible for mapping and delineating Maricopa County.
FEMA Adoption Process
Once floodplain delineation studies are completed on a local level, they are sent to FEMA for approval. This FEMA adoption process takes approximately six to nine months. In the interim period, the District uses this data as the "best available information" for floodplain management. Some delineation studies are not sent immediately to FEMA, during which time the District looks at options for reducing the floodplain.
Special Flood Hazard Area
On a FIRM, a Special Flood Hazard Area (SFHA) is noted with shading. An SFHA is an area with a one percent chance of being flooded in any given year, hence the property is in the 100-year floodplain. Any land area susceptible to being inundated by flood waters from any source is identified as a floodplain.
Newly Mapped Areas
If you are in a newly mapped area and required to purchase flood insurance FEMA’s website can provide information to help you work with your agent on the best rate. If you have an Elevation Certificate for a single family home that indicates your lowest adjacent grade is above the BFE you can use the FEMA MT-EZ form to submit a Letter of Map Amendment (LOMA) application to have FEMA determine if your home can be considered above/out of the floodplain.
The District is responsible for floodplain management and regulation in unincorporated Maricopa County, as well as in the communities of the following communities.
- Cave Creek
- El Mirage
- Gila Bend
- Litchfield Park
- Queen Creek
The following cities/towns conduct their own floodplain management. Contact the appropriate floodplain agency regarding floodplain questions using the phone numbers listed:
- City of Avondale - 623-333-4218
- City of Glendale - 623-930-3656
- City of Goodyear - 623-932-3004
- City of Peoria - 623-773-7210
- City of Phoenix - 602-262-4960
- City of Scottsdale - 480-312-2356
- City of Tempe - 480-350-8288
- Town of Fountain Hills - 480-816-5100
- Town of Gilbert - 480-503-6815
- Town of Paradise Valley - 480-348-3693