Query the First Street Foundation flood risk API to retrieve property-level flood depth and probability data for underwriting or portfolio risk display
domain: firststreet.org · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Obtain an API key, since First Street's API requires key-based authentication for all calls
Resolve each target property to a First Street ID (FSID), the unique location identifier the API expects instead of a raw address
Query flood depth/probability data using the documented depth thresholds, returned as depth-chance data across First Street's modeled year bands
If a visual layer is needed, call the map-tile endpoint with the event ID plus zoom level and x/y tile coordinates
Cross-check field definitions against First Street's current Technical Documentation before mapping into an underwriting system, since data is available via both API and bulk download and the two paths may expose fields differently
Known gotchas
The API keys on FSID, not street address — an address-to-FSID resolution step is required before any flood-data call will succeed
Depth-threshold and year-band definitions are specific to First Street's modeling methodology and should be pulled from the live data dictionary rather than hardcoded, since the methodology has been revised over time
Full historical/paid data tiers exist separately from the base documented API scope — confirm which access tier actually covers the fields your workflow needs before building on assumed free-tier coverage
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