Geocode the property address to obtain latitude and longitude coordinates.
Query the FEMA National Flood Hazard Layer (NFHL) via the ArcGIS REST API service that FEMA publishes publicly; pass the property coordinates to the identify or query endpoint for the Flood Zones layer.
Parse the returned flood zone designation (e.g., Zone AE, Zone X, Zone VE) from the FLD_ZONE attribute in the response.
Map the zone code to a human-readable risk level: Zone A/AE/AH/AO/VE are Special Flood Hazard Areas (high risk); Zone X (shaded) is moderate risk; Zone X (unshaded) is minimal risk.
Cache the flood zone result per parcel since FEMA FIRM maps are updated infrequently (check the EFF_DATE field for map effective date).
Display the flood zone designation alongside a note about flood insurance requirements for SFHA properties (federally backed mortgages require flood insurance in SFHA zones).
Known gotchas
FEMA NFHL coverage is not 100%; some jurisdictions have not participated in the NFIP mapping program and will return no data — handle the null case explicitly.
FIRM maps can be outdated; properties near recently improved drainage infrastructure may be in a different risk category than the map shows — surface the map effective date to users.
The FEMA ArcGIS service has rate limits and occasional downtime; implement retry logic with exponential backoff and consider caching aggressively.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp