Flood Preparedness
Houston floods. Here is what you need to know.
Last updated April 2026 | Sources: hcfcd.org, fema.gov, harriscountyfws.org
Three things make Houston uniquely flood-prone.
Flat terrain. Houston sits about 50 feet above sea level. Water does not flow downhill because there is very little hill. It pools.
Clay soil. The gumbo clay underneath Houston repels water instead of absorbing it. Rain runs off the surface instead of soaking in.
Development. Houston has no zoning. Concrete and asphalt replace prairie and wetland, eliminating natural sponges. Every new parking lot and subdivision pushes more water into bayous that were already at capacity.
The result: Houston has experienced more flooding events than any other major U.S. city. The region has had 5 federally declared flood disasters since 2015 -- the Memorial Day flood (2015), the Tax Day flood (2016), Hurricane Harvey (2017), Tropical Storm Imelda (2019), and the May 2024 derecho.
FEMA divides land into flood zones based on risk. The zones that matter most:
Zone A / AE (Special Flood Hazard Area): 1% annual chance of flooding. That sounds low, but over a 30-year mortgage, it is a 26% chance. If you have a federally backed mortgage in this zone, flood insurance is required.
Zone X (shaded): 0.2% annual chance (500-year floodplain). Insurance is not required but is available and recommended.
Zone X (unshaded): Minimal flood risk. But "minimal" in Houston is not zero. During Harvey, 70% of flooded homes were outside the 100-year floodplain.
To check your zone: 1. Go to msc.fema.gov (FEMA Flood Map Service Center) 2. Enter your address 3. View your Flood Insurance Rate Map (FIRM)
Harris County also maintains its own flood risk tool at harriscountyfws.org with more detailed local data, including bayou gauge levels and historical flood extents.
In August 2018, Harris County voters approved a $2.5 billion bond for flood control -- the largest flood bond in U.S. history. The bond funds 181 projects across the county.
Projects include widening and deepening bayous, building new stormwater detention basins, acquiring and demolishing repeatedly flooded homes (voluntary buyouts), and improving bridges that act as bottlenecks during high water.
As of 2026, the Flood Control District has completed or started construction on more than 120 of the 181 projects. You can track every project at hcfcd.org/bond-program, searchable by watershed and ZIP code.
The bond is funded by a property tax increase of about $5 per month for the median Harris County homeowner.
Houston's 22 bayous are not just drainage channels. The Bayou Greenways 2020 project, led by the Houston Parks Board, is building 150 miles of connected parks and trails along bayou corridors.
These greenways serve double duty. The natural buffers along bayou banks absorb stormwater, reducing downstream flooding. They also create car-free trails for walking, running, and cycling that connect neighborhoods across the city.
Buffalo Bayou Park (downtown to Shepherd Drive) is the flagship -- a 160-acre park along 2.3 miles of bayou with trails, playgrounds, a dog park, public art, and a nature play area. Brays Bayou Greenway connects the Third Ward to Pearland through 30 miles of trail.
The project is funded by a combination of city bonds, private donations, and the Houston Parks Board endowment. When complete, 60% of Harris County residents will live within 1.5 miles of a bayou trail.