Guadalupe County, TX Environmental Rules: Erosion Control (2026)

Outside the floodplain, unincorporated Guadalupe County does not require grading or drainage permits, because Texas counties lack general land-use authority. Inside FEMA-mapped floodplains along the Guadalupe River, Cibolo Creek, and their tributaries, grading, fill, and drainage changes require a floodplain development permit so the county can confirm the work does not raise the base flood elevation on adjacent land - a critical check in Flash Flood Alley. Subdivision plats reviewed by the county must show drainage that does not divert concentrated runoff onto neighboring tracts. Within Seguin, Schertz, Cibolo, and other incorporated cities, the city engineering department administers grading and drainage rules instead.