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Flood zone · Iowa

Flood zone in Iowa

Flood zone (FEMA NFHL) data for ZIP codes in Iowa. Pick a ZIP below to dive into the flood zone summary.

Last verified 2026-05-13 · methodology

What lands here

Pages show the flood zone code, what it means in plain English (1% annual chance zone, 0.2% annual chance zone, or outside mapped hazard), and the base flood elevation where assigned.

Source & refresh

FEMA NFHL. Refreshed quarterly loma updates. Primary source →

Iowa top concern

Radon Zone 1, agricultural water nitrates

Iowa is one of the highest-radon states in the US — uniformly Zone 1. Agricultural runoff drives EPA SDWIS nitrate violations in small rural systems and even Des Moines Water Works. Tornadoes peak April-June.

See Iowa state page for the full state-level rollup across all 12 dimensions.

Read more on flood zone

Editorial deep-dives explaining the source data, its limits, and how to read it.

3 Iowa ZIPs