{
 "name": "dyom-ucmr5-pfas-lithium",
 "title": "EPA UCMR 5 PFAS and lithium results by US public water system (Do Your Own Math compilation)",
 "version": "v1-2026-10-31",
 "licenses": [
  {
   "name": "CC-BY-4.0",
   "title": "Creative Commons Attribution 4.0",
   "path": "https://creativecommons.org/licenses/by/4.0/"
  }
 ],
 "sources": [
  {
   "title": "US EPA, UCMR 5 occurrence data (final dataset, August 2026)",
   "path": "https://www.epa.gov/system/files/other-files/2023-08/ucmr5-occurrence-data.zip"
  },
  {
   "title": "US EPA, SDWIS via Envirofacts (population served, source type, connections)",
   "path": "https://data.epa.gov/efservice/WATER_SYSTEM/PWS_ACTIVITY_CODE/A/PWS_TYPE_CODE/CWS/POPULATION_SERVED_COUNT/%3E/25000/ROWS/0:9999/JSON"
  },
  {
   "title": "US EPA, PFAS National Primary Drinking Water Regulation, 40 CFR 141.61 (26 April 2024)",
   "path": "https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas"
  }
 ],
 "created": "2026-11-06T04:09:29.470Z",
 "description": "One-time national monitoring (2023–2025), summarised per system and substance: samples, detections (results at or above the laboratory minimum reporting level), highest single value, MRL, sample window, the 2024 federal limit where one exists. Units: ng/L (lithium values are also ng/L in the files; pages show µg/L). Not a compliance record; not a measure of tap water in any building.",
 "resources": [
  {
   "name": "results",
   "path": "ucmr5-pfas-lithium-results-v1-2026-10-31.csv",
   "format": "csv",
   "mediatype": "text/csv",
   "schema": {
    "fields": [
     {
      "name": "pwsid",
      "type": "string",
      "description": "EPA public water system ID"
     },
     {
      "name": "system_name",
      "type": "string",
      "description": "System name as published by EPA"
     },
     {
      "name": "state",
      "type": "string"
     },
     {
      "name": "population_served",
      "type": "integer",
      "description": "From SDWIS; present only for community systems serving more than 25,000 people"
     },
     {
      "name": "source_type",
      "type": "string",
      "description": "SDWIS primary source code: SW, GW, GU, SWP, GWP, GUP"
     },
     {
      "name": "substance",
      "type": "string",
      "description": "PFOA, PFOS, PFHxS, PFNA, HFPO-DA, PFBS or lithium"
     },
     {
      "name": "samples",
      "type": "integer",
      "description": "UCMR 5 results read for this system and substance"
     },
     {
      "name": "detections",
      "type": "integer",
      "description": "Results reported as equal to a measured value (at or above the MRL)"
     },
     {
      "name": "highest_ngL",
      "type": "number",
      "description": "Highest single result, ng/L; empty when none detected"
     },
     {
      "name": "mrl_ngL",
      "type": "number",
      "description": "Minimum reporting level of the EPA method, ng/L"
     },
     {
      "name": "first_sample",
      "type": "date"
     },
     {
      "name": "last_sample",
      "type": "date"
     },
     {
      "name": "limit_2024_ngL",
      "type": "number",
      "description": "2024 MCL where one exists (PFOA, PFOS 4; PFHxS, PFNA, HFPO-DA 10); empty for PFBS and lithium"
     },
     {
      "name": "above_limit",
      "type": "string",
      "description": "yes when highest_ngL exceeds limit_2024_ngL in at least one sample; a measurement, not a violation"
     }
    ]
   }
  },
  {
   "name": "systems",
   "path": "ucmr5-systems-v1-2026-10-31.csv",
   "format": "csv",
   "mediatype": "text/csv",
   "schema": {
    "fields": [
     {
      "name": "pwsid",
      "type": "string"
     },
     {
      "name": "system_name",
      "type": "string"
     },
     {
      "name": "state",
      "type": "string"
     },
     {
      "name": "population_served",
      "type": "integer"
     },
     {
      "name": "source_type",
      "type": "string"
     },
     {
      "name": "service_connections",
      "type": "integer"
     },
     {
      "name": "samples_total",
      "type": "integer"
     },
     {
      "name": "any_detection",
      "type": "string"
     },
     {
      "name": "substances_above_2024_limit",
      "type": "string"
     },
     {
      "name": "first_sample",
      "type": "date"
     },
     {
      "name": "last_sample",
      "type": "date"
     },
     {
      "name": "page_url",
      "type": "string"
     }
    ]
   }
  }
 ]
}