Data sources

Every dataset behind the report card, with its source, download date, license, attribution and known limitations. Federal datasets are U.S. government works in the public domain; we credit each one so you can check every fact.

EPA Toxics Release Inventory (TRI)

Publisher: U.S. Environmental Protection Agency
Dataset: TRI Basic Data Files, reporting years 2020–2024 (California, Oregon, Nevada, Arizona)
Link: https://www.epa.gov/toxics-release-inventory-tri-program/tri-basic-data-files-calendar-years-1987-present
Downloaded: 2026-09-25 (loaded)
Vintage: TRI reporting years 2020–2024
License: Public domain (U.S. government work)
Attribution: U.S. EPA, Toxics Release Inventory Program, TRI Basic Data Files.
Used for: Pollution section: TRI facilities within 1 and 3 miles, their industry, latest reporting year, on-site releases and top chemicals.
Limitations: TRI covers only facilities above industry, employee and chemical thresholds. Releases are self-reported estimates. Quantities are totals for the year, not concentrations or exposures. Dioxin-like compounds reported in grams are converted to pounds. Facility coordinates are the ones in the TRI Basic Data Files. EPA's Envirofacts TRI tables sometimes give a different point, or none. For example, WILBUR-ELLIS CO FRESNO sits 0.48 mi from Fresno City Hall by Envirofacts' preferred coordinates but 3.4 mi by the Basic Data File, so a facility near the 1- or 3-mile ring can fall on either side depending on the source.

EPA Superfund National Priorities List (NPL)

Publisher: U.S. Environmental Protection Agency
Dataset: Superfund National Priorities List (NPL) Sites with Status Information (EPA feature service)
Link: https://services.arcgis.com/cJ9YHowT8TU7DUyn/arcgis/rest/services/Superfund_National_Priorities_List_(NPL)_Sites_with_Status_Information/FeatureServer/0
Downloaded: 2026-09-25 (loaded)
Vintage: EPA NPL feature service (downloaded 2026-09-24)
License: Public domain (U.S. government work)
Attribution: U.S. EPA, Superfund National Priorities List (NPL) Sites with Status Information.
Used for: Pollution section: final, proposed and deleted NPL sites within 1 and 3 miles, with a link to each site's EPA profile.
Limitations: Each site is one representative point; actual site boundaries and contamination plumes can be larger. Deleted sites are shown but not counted in the grade.

EPA ECHO (Enforcement and Compliance History Online)

Publisher: U.S. Environmental Protection Agency
Dataset: ECHO Exporter (national facility file, refreshed weekly by EPA)
Link: https://echo.epa.gov/tools/data-downloads
Downloaded: 2026-09-25 (loaded)
Vintage: ECHO Exporter (published 2026-09-24)
License: Public domain (U.S. government work)
Attribution: U.S. EPA, Enforcement and Compliance History Online (ECHO), ECHO Exporter.
Used for: Pollution section: active facilities within 1 mile with a formal enforcement action in the last 5 years, current significant noncompliance or high-priority violation, or a significant-violation quarter in the last 3 years.
Limitations: Compliance data comes from EPA and state systems and can lag or contain errors. A violation is not a finding of harm. About 1% of ECHO rows have no FRS registry ID; they are keyed by program ID. ECHO's demographic columns are deliberately never read.

FEMA National Flood Hazard Layer (NFHL)

Publisher: Federal Emergency Management Agency
Dataset: NFHL statewide file geodatabase for California (NFHL_06_20260910)
Link: https://msc.fema.gov/portal/advanceSearch
Downloaded: 2026-09-25 (loaded)
Vintage: NFHL_06_20260910 (effective through 06/10/2026, latest LOMR 09/11/2026)
License: Public domain (U.S. government work)
Attribution: FEMA, National Flood Hazard Layer (NFHL), Flood Map Service Center.
Used for: Flood section: the FEMA flood zone at the location, the share of the hexagon inside the 1%-annual-chance floodplain (Special Flood Hazard Area), and the FIRM panel and its effective date.
Limitations: This is not an official flood zone determination. Only FEMA or a licensed professional, using the effective FIRM and any Letters of Map Change, can determine a building's zone. Some areas have no digital FIRM coverage (reported as "Not enough data"). Maps reflect the study date, not current conditions.

OpenFEMA NFIP Redacted Claims (v3)

Publisher: Federal Emergency Management Agency
Dataset: FIMA NFIP Redacted Claims, version 3 (`/api/open/v3/NfipClaims`); plus the Census 2020–2010 tract relationship file
Link: https://www.fema.gov/openfema-data-page/nfip-redacted-claims-v3
Downloaded: 2026-09-25 (loaded)
Vintage: NFIP claims 1978–2026 (as of 2026-09-24)
License: Public domain (U.S. government work). OpenFEMA terms: https://www.fema.gov/about/openfema/terms-conditions
Attribution: FEMA, OpenFEMA Dataset: FIMA NFIP Redacted Claims - v3. This product uses the FEMA OpenFEMA API but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Used for: Flood section: paid NFIP claims in the census tract and claims per 1,000 housing units (2020 Census housing counts).
Limitations: Covers only insured properties that filed claims. Claims locations are redacted to the block group. About 26% of claims carry 2010-vintage tract codes; these are apportioned to 2020 tracts by shared land area, so some counts are estimates. v2 of this dataset is deprecated (frozen 2026-06-01).

USFS Wildfire Risk to Communities (2nd edition)

Publisher: USDA Forest Service, Rocky Mountain Research Station
Dataset: Wildfire Risk to Communities: Spatial datasets of landscape-wide wildfire risk components for the United States (2nd Edition), RDS-2020-0016-2, California state file
Link: https://doi.org/10.2737/RDS-2020-0016-2
Downloaded: 2026-09-25 (loaded)
Vintage: WRC 2nd edition (2024; LANDFIRE 2020 fuels)
License: Public domain (U.S. government work)
Attribution: Scott, J. H.; Dillon, G. K.; Jaffe, M. R.; et al. 2024. Wildfire Risk to Communities (2nd Edition). Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2020-0016-2
Used for: Wildfire section: Risk to Homes (Risk to Potential Structures), Wildfire Likelihood (annual burn probability) and Exposure Type (direct, indirect, not exposed) at the location.
Limitations: These are modeled, landscape-scale values (30 m) and do not account for a specific home's construction, defensible space or recent fuel changes. Values are shown as published; this site does no additional modeling.

USFS Wildfire Hazard Potential 2023

Publisher: USDA Forest Service, Fire Modeling Institute
Dataset: Wildfire Hazard Potential for the United States (270-m), version 2023 (4th Edition), RDS-2015-0047-4, classified layer
Link: https://doi.org/10.2737/RDS-2015-0047-4
Downloaded: 2026-09-25 (loaded)
Vintage: WHP 2023 (4th edition, published 2024)
License: Public domain (U.S. government work)
Attribution: Dillon, G. K. 2023. Wildfire Hazard Potential for the United States (270-m), version 2023. 4th Edition. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2015-0047-4
Used for: Wildfire section: the dataset's own class (Very Low, Low, Moderate, High, Very High, Non-burnable, Water) at the location.
Limitations: 270 m resolution. It describes wildland fuel hazard for fire management, not the risk to a particular home.

CAL FIRE Fire Hazard Severity Zones

Publisher: California Department of Forestry and Fire Protection (CAL FIRE), Office of the State Fire Marshal
Dataset: FHSZ in State Responsibility Areas (map dated 2023-09-29, effective 2024-04-01) and in Local Responsibility Areas (map dated 2025-03-24)
Link: https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones
Downloaded: 2026-09-25 (loaded)
Vintage: CAL FIRE FHSZ: SRA map 2023-09-29 (effective 2024-04-01); LRA map 2025-03-24
License: California state public data. See CAL FIRE's terms of use on the source page.
Attribution: CAL FIRE / Office of the State Fire Marshal, Fire Hazard Severity Zones.
Used for: Wildfire section: the official state hazard zone. A Very High zone caps the wildfire grade at D and a High zone caps it at C.
Limitations: California only. LRA maps are adopted by each local government, which may add zones. Check your city or county for the adopted map. This is not a Natural Hazard Disclosure report.

USGS 2023 National Seismic Hazard Model

Publisher: U.S. Geological Survey
Dataset: Data Release for the 2023 U.S. 50-State National Seismic Hazard Model: chance of potentially damaging shaking (MMI VI) in 100 years (0.05° grid, site-amplified); PGA with 2% probability of exceedance in 50 years (site class B/C); equivalent MMI
Link: https://www.sciencebase.gov/catalog/item/644af897d34e45f6ddcd13b3
Downloaded: 2026-09-25 (loaded)
Vintage: USGS 2023 50-State NSHM (data release 2023)
License: Public domain (U.S. government work)
Attribution: U.S. Geological Survey, 2023 50-State National Seismic Hazard Model (Petersen et al., 2023), https://doi.org/10.5066/P9GNPCOD
Used for: Earthquake section: chance of potentially damaging shaking in 100 years (interpolated at the location) and its USGS map band, PGA 2%-in-50-years and its Modified Mercalli Intensity.
Limitations: Regional hazard, not a site-specific study. The PGA and MMI values assume a reference site class (B/C) and local soils can amplify or reduce shaking. Liquefaction, landslide and fault-rupture zones are not included.

OpenFEMA Disaster Declarations Summaries

Publisher: Federal Emergency Management Agency
Dataset: Disaster Declarations Summaries v2
Link: https://www.fema.gov/openfema-data-page/disaster-declarations-summaries-v2
Downloaded: 2026-09-25 (loaded)
Vintage: OpenFEMA declarations through 2026-08-04
License: Public domain (U.S. government work). OpenFEMA terms: https://www.fema.gov/about/openfema/terms-conditions
Attribution: FEMA, OpenFEMA Dataset: Disaster Declarations Summaries - v2. This product uses the FEMA OpenFEMA API but is not endorsed by FEMA.
Used for: Disaster history: county declarations (major disaster, emergency, fire management) over the last 30 years, by incident type, plus the 5 most recent.
Limitations: Declarations are county-wide administrative events and don't show which neighborhoods were affected. Statewide declarations are counted for every county. Tribal declarations without a county are not attributed to counties.

U.S. Census Bureau 2020 Census blocks

Publisher: U.S. Census Bureau
Dataset: TIGER/Line 2020 tabulation blocks with 2020 Census population and housing unit counts (tl_2020_06_tabblock20)
Link: https://www2.census.gov/geo/tiger/TIGER2020/TABBLOCK20/
Downloaded: 2026-09-25 (loaded)
Vintage: 2020 Census (P.L. 94-171 block counts)
License: Public domain (U.S. government work)
Attribution: U.S. Census Bureau, 2020 Census, TIGER/Line Shapefiles.
Used for: Choosing which hexagons get reports (any hexagon touching a block with residents); housing-unit weights, so grades compare a home with other homes in the state; tract assignment; the denominator for NFIP claims per 1,000 homes.
Limitations: Homes built after 2020 are not counted. Very large rural blocks spread their housing units evenly across the hexagons they touch.

U.S. Census Bureau TIGER/Line counties, places and ZCTAs

Publisher: U.S. Census Bureau
Dataset: TIGER/Line 2025: counties, places (cities, towns and Census Designated Places), ZIP Code Tabulation Areas (ZCTA5 2020)
Link: https://www2.census.gov/geo/tiger/TIGER2025/
Downloaded: 2026-09-25 (loaded)
Vintage: TIGER/Line 2025
License: Public domain (U.S. government work)
Attribution: U.S. Census Bureau, TIGER/Line Shapefiles.
Used for: City and neighborhood names on reports and share images; ZIP and city area pages.
Limitations: ZCTAs approximate USPS ZIP code delivery areas and are not identical to them.

U.S. Census Bureau American Community Survey (context only)

Publisher: U.S. Census Bureau
Dataset: ACS 2020–2024 5-year estimates, tables B25077 (median home value), B25064 (median gross rent), B25035 (median year structure built), census tracts
Link: https://www2.census.gov/programs-surveys/acs/summary_file/2024/table-based-SF/
Downloaded: 2026-09-25 (loaded)
Vintage: ACS 2020-2024 5-year
License: Public domain (U.S. government work)
Attribution: U.S. Census Bureau, American Community Survey 5-Year Estimates.
Used for: Area context shown as plain facts only. Never graded, never used in any score, color, ranking or AI summary.
Limitations: These are survey estimates with margins of error. Top-coded values ($2,000,000+ home value, $3,500+ rent, built 1939 or earlier) are shown as such.

Geocoding: U.S. Census Bureau Geocoder

Publisher: U.S. Census Bureau
Dataset: Census Geocoder, one-line address endpoint, `Public_AR_Current` benchmark
Link: https://geocoding.geo.census.gov/geocoder/
Downloaded: Live at search time. Results are cached for 90 days, keyed by a hash of the normalized address.
Vintage: Current benchmark
License: Public domain (U.S. government work)
Attribution: U.S. Census Bureau Geocoder.
Used for: Turning a typed address into coordinates.
Limitations: Some addresses, especially new construction and rural routes, may not match. Matches are interpolated along street segments.

Map tiles: OpenFreeMap

Publisher: OpenFreeMap (tiles), OpenMapTiles schema, OpenStreetMap contributors (data)
Dataset: OpenFreeMap "positron" vector style
Link: https://openfreemap.org/
Downloaded: Live in the browser
Vintage: Current
License: Map data © OpenStreetMap contributors (ODbL). OpenFreeMap is free to use with no usage limits or API keys, including commercial use.
Used for: The small location map on result pages.
Limitations: Basemap only; no hazard data comes from it.