Floodplain (FEMA) Maps & Flood Information

Preliminary Flood Maps in Williamson County, TX Ready for Public View

Homeowners, renters and business owners in Williamson County are encouraged to look over newly released preliminary flood maps in order to determine their flood risks and make informed decisions.

County officials and the Federal Emergency Management Agency (FEMA) are presenting the preliminary maps to communities and unincorporated areas in Williamson County in order to help leaders and residents identify known flood risks and use that information to make decisions about buying flood insurance and any future development.

View the Interactive Map with General Overview of Changes.

Release of New Floodplain Maps

The Department of Homeland Security's Federal Emergency Management Agency (FEMA) is in the process of releasing new floodplain maps for the portion of the City of Cedar Park that lies within Williamson County. FEMA identifies floodplains in order to calculate flood risks for insurance purposes, particularly within Special Flood Hazard Areas (SFHA). SFHAs are defined as the area that will be inundated by the flood event having a 1% chance of being equaled or exceeded in any given year. The 1% annual chance flood is also referred to as the base flood or 100-year flood.

The new maps are a result of a multi-year study of the Upper Brushy Creek watershed prepared by the Texas Water Development Board (TWDB) and the Upper Brushy Creek Water Control and Improvement District (UBCWCID). The City of Cedar Park was an active member of the Technical Advisory Committee for the UBCWCID watershed study. The new floodplain maps are the result of new technology and data which yields a better assessment of where flooding is most likely to occur close to creeks and more accurately predict floodplain boundaries. In most cases, mapped drainage boundaries have not changed.

Floodplain Comparison Mapping Tool

Williamson County has prepared a Simple Mapping Tool that compares the current effective floodplain limits to the proposed new floodplain limits. Simply click the blue "I want to…" button to see a list of options. Use the "Address Search" to enter an address and zoom the map into the appropriate area.

Alternatively, the following link is provided by FEMA to access the same information, however, the Williamson County webpage linked previously is more user friendly:

  • On January 30, 2017, FEMA posted digital copies of preliminary Flood Insurance Rate Maps (FIRM), Flood Insurance Study (FIS) report materials, and supporting data on their Map Service Center website
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