1. U.S. Census Bureau Geocoding Services API
| Agency | U.S. Census Bureau (Department of Commerce) |
|---|---|
| Dataset / Product | Public_AR_Current Address Geocoder REST Service |
| Official URL | https://geocoding.geo.census.gov/ |
| Query Method | HTTP GET parsed structured/unstructured address geocode query |
| Fields Consumed | Matched address, WGS84 latitude/longitude, TIGER/Line ID, benchmark |
| Known Limitations | Interpolated street centerline ranges (TIGER/Line). Does not represent surveyed parcel boundaries. |
2. USGS / MRLC NLCD 2021 Land Cover
| Agency | U.S. Geological Survey (USGS) & Multi-Resolution Land Characteristics Consortium (MRLC) |
|---|---|
| Dataset / Product | NLCD 2021 Land Cover (NLCD_2021_Land_Cover_L48) |
| Official URL | https://www.mrlc.gov/ |
| Query Method | WMS 1.1.1 GetFeatureInfo coordinate point query |
| Fields Consumed | PALETTE_INDEX mapped to official NLCD 30m land cover class |
| Known Limitations | Represents the mapped 30-meter raster cell containing the Census-geocoded coordinate. Does not determine parcel land use or zoning. |
3. USDA NRCS Soil Data Access (SSURGO)
| Agency | Natural Resources Conservation Service (USDA NRCS) |
|---|---|
| Dataset / Product | Soil Data Access (SDA) WQL Tabular REST Service |
| Official URL | https://sdmdataaccess.nrcs.usda.gov/ |
| Query Method | SDA PostQuery WQL spatial point query (`SDA_Get_Mupolygonkey_from_pt`) |
| Fields Consumed | MUKEY, Map Unit Name, Map Unit Symbol, Dominant Component Name & %, Slope Range, Drainage Class, Hydrologic Group |
| Known Limitations | SSURGO map units represent soil complexes containing multiple component soils. Does not prove point-specific soil engineering suitability. |
4. USGS 3D Elevation Program (3DEP)
| Agency | U.S. Geological Survey (USGS / Department of the Interior) |
|---|---|
| Dataset / Product | 3DEP Elevation Point Query Service (EPQS) |
| Official URL | https://www.usgs.gov/3dep |
| Query Method | HTTP GET JSON point query (`/v1/point`) |
| Fields Consumed | Elevation value in meters, converted elevation in feet, raster ID |
| Known Limitations | Digital Elevation Model (DEM 1/3 arc-second ~10m resolution). Non-survey-grade ground elevation. |
5. USGS Watershed Boundary Dataset (WBD HUC12)
| Agency | U.S. Geological Survey & USDA NRCS |
|---|---|
| Dataset / Product | Watershed Boundary Dataset (WBD Layer 6 MapServer) |
| Official URL | https://www.usgs.gov/wbd |
| Query Method | ESRI MapServer layer 6 spatial point query (`esriSpatialRelIntersects`) |
| Fields Consumed | HUC12 code, subwatershed name, states, area in sq km and acres, downstream HUC |
| Known Limitations | Hydrologic subbasin boundary (HUC12). Does not determine local property drainage patterns. |
6. FEMA National Flood Hazard Layer (NFHL)
| Agency | Federal Emergency Management Agency (FEMA) |
|---|---|
| Dataset / Product | NFHL Layer 28 MapServer (`S_Fld_Haz_Ar`) |
| Official URL | https://hazards.fema.gov/gis/nfhl/ |
| Query Method | ESRI MapServer layer 28 spatial point query (`esriSpatialRelWithin`) |
| Fields Consumed | FLD_ZONE, ZONE_SUBTY, SFHA_TF, FLD_AR_ID |
| Known Limitations | Requires live NFHL GIS query response. Upstream resets or timeouts return explicit UNAVAILABLE state without zone inference. |
7. Documented Upstream Provider Blockers & Status
| Provider / Service | Attempted Endpoint | Observed Status | Technical Reason for Handling |
|---|---|---|---|
| USFWS National Wetlands Inventory (NWI) | `fwsprimary.wim.usgs.gov/server/rest/services/Wetlands/MapServer/0/query` | HTTP 500 Query Error | USFWS primary MapServer currently fails direct ESRI point/envelope queries. Handled gracefully as `UNAVAILABLE` without fake wetland data. |
| EPA AirNow / OpenAQ AQI | `api.openaq.org/v2/latest` | HTTP 410 Gone / Key Required | OpenAQ v1/v2 endpoints retired; OpenAQ v3 and EPA AirNow require authenticated API keys. Handled as `UNAVAILABLE` without fake AQI defaults. |