The U.S. Federal Emergency Management Agency (FEMA) is in the process of updating Flood Insurance Risk Maps (FIRMs). FEMA identifies floodplains in order to calculate flood risks for insurance purposes, particularly within Special Flood Hazard Areas (SFHA). These are defined as “the area that will be inundated by the flood event having a 1 percent chance of being equaled or exceeded in any given year. The 1 percent annual chance flood is also referred to as the base flood or 100-year flood.”

Williamson County residents can check to see if their property is in a floodplain here. Click on the “I want to” tab to complete an address search.

Preliminary Mapping Viewer

This tool compares the existing maps to the proposed maps.
  • Purple shading indicates no change
  • Green shading indicates areas to be removed from existing floodplain
  • Red shading indicates areas to be added to existing floodplain



Frequently Asked Questions


Why are floodplain maps being updated?

The maps are being updated because the majority of the maps are based on analyses that were performed over 25 years ago. Watershed conditions such as topography have changed and there has been significant added development. Furthermore, analysis tools and historical data collection have improved over time and will increase map accuracy.

Flood hazard mapping is an important part of the National Flood Insurance Program (NFIP), as it is the basis of NFIP regulations and flood insurance requirements. The Federal Emergency Management Agency (FEMA) maintains and updates data through Flood Insurance Rate Maps (FIRMs) and risk assessments.

How often are they updated?

There is no set timeline. Flood zone designations may be revised when new and more accurate information becomes available because of a FEMA-funded restudy or because the community makes the information available to FEMA. Several factors influence the frequency with which flood maps may be updated, such as the extent of new development and the completion of flood-control projects.

There are no comprehensive updates foreseen in the next 10 years.

Who initiated the update?

FEMA initiated a partial update in 2010. In 2012, the Upper Brushy Creek Water Control and Improvement District (WCID) initiated a flood protection plan that included watershed modeling. Communities within the watershed desired to use the modeling as the basis for a comprehensive mapping update. The WCID then partnered with FEMA and the Texas Water Development Board to complete the process.

Where is this happening?

The updated maps encompass the Upper Brushy Creek WCID boundary, which includes much of southwest Williamson County.

What is the general impact of new floodplains? Are more properties going to be in the floodplain?

In general, updated flood levels will increase, i.e., more properties are likely to be in the updated floodplain. When new maps are issued, your risk may have changed along with your flood insurance requirements. Property owners are encouraged to review the updated maps and discuss implications with their insurance agent. If you’ve been mapped into a high-risk area, you will be required to purchase flood insurance if your mortgage is through a federally regulated or insured lender. It is possible to save money through a process known as grandfathering provided by the NFIP.

If your property is mapped out of a high-risk area, your flood insurance costs will likely decrease.

What are the steps in the process and when will it be complete?

We anticipate that the Physical Map Revision (PMR) process will be completed by FEMA in early 2019. To ensure those affected by the PMR have the opportunity to provide input, FEMA has procedures that include a community comment period and a 6-month compliance period to update ordinances while the new maps are printed and distributed. We anticipate the public comment and appeal period to be in early 2018.

Who should I talk to if I have questions?

Property owners or other persons who wish to follow the progress of the PMR should consult their community’s Floodplain Administrator. This is the local official who keeps all of the community’s flood hazard maps and Flood Insurance Study (FIS) report, and who corresponds with FEMA at various stages of the revision process.

In the City of Round Rock, City Engineer Danny Halden is the Floodplain Administrator. For inquiries, please email him at floodplain@roundrocktexas.gov or call him at 512-218-6610.

The status of ongoing map revisions can also be checked on the FEMA website, or by calling the FEMA Map Information exchange toll free at 1-877-FEMA MAP (1-877-336-2627)

What is the plan for educating the public on all of this?

We will educate the public through our usual channels, including print and email newsletters, websites, social media and working with the news media.