Flower Mound, TX Environmental Rules: Flood Zones (2026)

The Town of Flower Mound straddles two major watersheds: the Denton Watershed drains to Lake Grapevine, and the Elm Fork Trinity Watershed drains to Lake Lewisville. FEMA-designated Special Flood Hazard Areas (Zones A and AE) occur along Bakers Branch, Graham Branch, McKamy Creek, Sharps Branch, Timber Creek, Whites Branch, Wichita Chase, Wichita Creek, their tributaries, and low-lying areas surrounding Lake Grapevine. The U.S. Army Corps of Engineers manages Lake Grapevine dam and flood control operations, and lake level fluctuations can affect flood risk in adjacent areas. Any property improvements, fill placement, or construction within a FEMA-mapped SFHA require a Floodplain Development Permit from the town. New residential construction in flood zones must have the lowest floor elevated at least one foot above the base flood elevation. Substantial improvement or substantial damage (exceeding 50 percent of market value) triggers full compliance with current floodplain regulations. The town participates in the National Flood Insurance Program; failure to comply with floodplain regulations risks community-wide expulsion from NFIP. Homeowners in SFHA areas with federally backed mortgages are required to carry flood insurance. Contact the Floodplain Manager at (972) 874-6000 for flood zone determinations and permit requirements.