Flooding Is a Real Risk in Williamson County

The San Gabriel River and Brushy Creek watershed are the main flood threats in Williamson County. A major disaster was declared after devastating floods in July 2025, with an estimated $25 million in damage to public property alone. Flash floods can happen quickly across the county.

FEMA revised flood maps for the county in 2019 using studies by the Texas Water Development Board and the Upper Brushy Creek WCID. If you build or improve property in or near a 100-year floodplain in unincorporated areas, you need a Floodplain Development Permit. Structures must be elevated at least one foot above base flood elevation. Check current maps at msc.fema.gov or the county's GIS page. Call the County Engineer at 512-943-3330 with questions.