Floodplain Overview 

The City of Grand Prairie participates in the National Flood Insurance Program (NFIP) of the Federal Emergency Management Agency (FEMA). As a participating community, the City has adopted Floodplain Management practices through several ordinances that severely limit the development allowed in 100-year floodplains (the area inundated by a storm that has a 1% chance of happening in any year). For property with any portion located within the 100-year floodplain, regardless of structure location, a flood insurance policy may be required.

The City of Grand Prairie standards require all new structures be constructed two feet above the existing water surface elevation of the 100-year floodplain, or one foot above the "ultimate" water surface elevation. When developing along a major creek within the City of Grand Prairie, the developer must submit a Flood Study to the city showing the 100-year floodplain and water surface elevation based on both current land-use and future land-use assumptions. [See Floodplain Development Requirements for more information.]

Community Rating System (CRS)

The City of Grand Prairie participates in the Community Rating System (CRS). The CRS is a subset of the NFIP. It is a voluntary incentive program, which recognizes and encourages community floodplain management activities which exceed the minimum NFIP requirements. As a result, flood insurance premium rates are discounted to reflect the reduced flood risk resulting from the community actions meeting the three goals of the CRS: 1) Reduce flood losses, 2) Facilitate accurate insurance rating, and 3) Promote the awareness of flood insurance. Community participation on the CRS is in addition to participation in the NFIP. Participation in the NFIP does not automatically include participation in the CRS. As of September 2012, the City of Grand Prairie has a CRS ranking of 5, which qualifies for a discount of 25% for properties in the SFHA.

City-Wide Master Drainage Plan Road Map

There are over 19,000 acres of floodplain in the City of Grand Prairie. This accounts for 36.7% of the total City area, more than any other City in the region. Large floodplain areas include Joe Pool Lake, Mountain Creek, and the West Fork Trinity River floodplain.

City flooding and drainage problems are key issues when planning for the safety, health, and quality of life for Grand Prairie citizens. As of 2012, over 2,500 drainage complaints have been submitted to City staff. Also, land development in Grand Prairie continues to increase over time, thus increasing the potential for faster and greater flooding chances at many locations across the City. Many successful projects have been built in the City to provide flood control, including channels, culverts, bridges, detention facilities, and lakes. However, many areas are still in need of additional flood control measures or repairs and improvements to existing flood control structures. The City-Wide Drainage Master Plan Road Map establishes the processes for future flood control planning for the City of Grand Prairie.

The City's primary goal and objective of the City-Wide Drainage Master Plan is to cost-effectively manage flood or storm waters within budgeting constraints so that conditions don't get worse as new and infill areas are developed – while evaluating and making conditions better (prioritized improvements) in the areas of the City that are already developed.

Flood Insurance Rate Maps (FIRM)

Flood Insurance Rate Maps delineate the floodplains throughout the United States and are used by lenders and insurance companies to determine if your property is in a floodplain. Paper copies are available for viewing at the Development Center or may be viewed and printed online for free at the FEMA Flood Map Store.

Letters of Map Revisions (LOMR)

The delineation of the floodplain limits can change. If a developer wishes to alter and/or fill a portion of the floodplain, they must prepare a Flood Study showing no adverse effects or substantial changes in the water surface elevation. This flood study, along with a detailed application, may be submitted to FEMA to be considered for a Letter of Map Revisions (LOMR). If approved, the LOMR serves as an official revision to the FIRM. Individual property owners may also contest the floodplain designation for their property by submitting information to FEMA for a Letter of Map Amendment (LOMA).

The city has received many LOMRs and LOMAs within our city limits. Lenders and Insurance Companies are not always aware of these changes, so it may be necessary to call the Engineering Services Department at 972-237-8157 to determine if the floodplain map for your area has changed and to receive a copy of the change. Many Letters of Map Change can also be obtained online from the FEMA Flood Map Store

Future Flood Insurance Rate Maps

FEMA, with the cooperation of local communities and consulting engineers, is in the process of converting paper FIRMs into digital format and updating them with the latest data in a process called Map Modernization. This process began in the spring of 2004 for Dallas, Johnson, Ellis and Tarrant counties. Revised preliminary maps for Johnson, Ellis, Dallas and Tarrant counties were submitted to the local communities for review. Since that time, the maps for Tarrant County were finalized and became effective in September 2009. The maps for Johnson County were finalized and became effective in December 2012. The maps for Ellis County were finalized and became effective in June 2013. The maps for Dallas County are still in the preliminary phase. It is anticipated that the Dallas County maps will become effective in 2014. We have integrated both the preliminary and effective DFIRM data into the city's Geographic Information System (GIS). This integration will allow property lines and aerial photos to be superimposed over the floodplain delineations for easier floodplain determination. The newer maps will show areas that have been removed from the mapped limits of the floodplain and areas that have been included (that were not included before) in the mapped limits of the floodplain.

A Frequently Asked Questions page (PDF) explains what to do if your property has been determined to be in or out of the mapped limits of the newer floodplain.