The areas in red above mark some of the new additions to the legally-gotta-buy-flood-insurance zones on FEMA’s recently revised flood maps. The agency’s interactive online viewer lets you mix-and-match a few data sets for Harris County (as well as Galveston, Fort Bend, and Wharton), compare the old mapped flood zone boundaries to proposed new ones, or look only at what would change — a FEMA spokesperson told Houston Public Media that about 8,000 properties have been added to the list in Harris County, while only about 400 were dropped.

Those acid-green highlights are areas that have been removed from the special flood hazard zone by the updated map (while blue shows areas that have just changed floodplain classification some other way. Bits of brown and yellow in other areas of the map show places added or removed (respectively) from the floodway. The updates above to the mandatory flood insurance zone (legally called the Special Flood Hazard Area) are set to go into effect in January, as shown above. Buffalo Bayou and its tributaries are pretty marked up:

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The big patches of green in the San Jacinto River highlight a few of the slowly growing islands where dredging sediment gets dumped:

Moving south, here are the changes around Clear Lake and Armand Bayou:

Meanwhile, here’s a sneak peak at what might happen to the flood maps in the western area of the county, if proposed changes are approved: some areas west of the Addicks and Barker reservoirs could get large swaths added to the mandatory flood insurance zone, particularly in a few places outside the Grand Pkwy. that drain into Bear and Cypress creeks:

Images: FEMA RiskMap6

Flood Insurance Ebb and Flow