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FEMA Draft Maps Show Harris County 100-Year Floodplain Expanding 43%

The draft now moves into local review before a public comment period with potential appeals, delaying any regulatory effect.

Overview

  • An early FEMA release indicates the 100-year floodplain would add about 130 square miles and the 500-year floodplain would grow roughly 30%, while mapped floodways would shrink about 5%.
  • Updated hydrologic modeling reflects rainfall rates more than 30% higher than past assumptions and includes far more channels, with decades of development also cited as a driver of wider flood zones.
  • Some neighborhoods show reduced risk due to recent mitigation projects, with officials pointing to work along Brays, White Oak, and Hunting bayous and examples like parts of Meyerland.
  • Properties newly placed in the 100-year floodplain would generally face a flood insurance requirement for federally backed mortgages, and experts warn FEMA’s Risk Rating 2.0 has already pushed many premiums above $1,000.
  • Local officials have 30 days to review the draft before a broader release after a 60-day preparation window, with HCFCD planning a public map viewer and outreach as county leaders press for greater transparency.