Know your data sources.

California EPA — DTSC Envirostor cleanup database + OEHHA CalEnviroScreen + DTSC HWTS. - searchEnvirostorSites ⭐ ~13.7K cleanup sites. 13 site_types. county UPPERCASE - searchCalEnviroScreen ⭐ ~8K census tracts. PiP via {lat, lon}. Filter minCIscoreP/minCIdecile - searchHazardousWasteFacilities ~107K HWTS RCRA handlers (G/T/TSDF). NO county - searchBrownfields = Envirostor scoped to Voluntary Cleanup + Calmortgage + School Cleanup - getServiceInfo upstream quirks: Authoritative owners only — DTSC_Admin (Envirostor + HWTS) on services3.arcgis.com/Oy2JTCD10wkoelxS, Kelsey.Ranjbar_OEHHA (CalEnviroScreen 4.0) on services1.arcgis.com/PCHfdHz4GlDNAhBb. No standalone Brownfields Feature Service exists; modeled via Envirostor site_type filter.

California Geologic Energy Management Division (CalGEM) WellSTAR — wells, facilities, incidents, notices. Public ArcGIS REST, no auth. WELLS: searchWells, getWellDetail, countWells, searchWellsByRadius FACILITIES / REGULATORY: searchFacilities, searchIncidents, searchNotices CRITICAL USAGE RULES: 1. API numbers are 8-10 digits (California format) 2. Use searchWellsByRadius for geographic queries (radiusMiles default 5) 3. searchWells accepts intuitive aliases like { status: 'active', type: 'oil' } and maps them to CalGEM codes 4. searchNotices supports county by matching county API prefixes and returns most recent notices first 5. bbox params are [minLon, minLat, maxLon, maxLat]

California State Lands Commission — coastal tidelands + offshore O&G + School Lands + Granted Lands. - searchOffshoreLeases ⭐ ~34 polygons (Active 26 / Inactive 8) — Long Beach/Wilmington/Huntington - searchOnshoreLeases ⭐ ~5.5K leases (76 Oil & Gas). Defaults TypeofLease='Oil & Gas Lease' - searchSchoolLands ~1.3K PLSS polygons (CNTY field, NOT COUNTY) - searchGrantedLands ~115 tidelands grants. Active 105 / Repealed 4 upstream quirks: AGOL services3.arcgis.com/5aaQCuq3e4GRvkFG owned by CA_State_Lands_Commission. Offshore lean schema (PRC + Lease_Stat only). CSLC Leases use ISO date strings + Lat/Lon strings + geometry.x/y. School_Lands has CNTY (4-char), 'Tinity'->'Trinity' typo. Granted_Lands COUNTY has 'Marin'/'Marin County' variants.

California State Water Resources Control Board + DWR — drinking water systems + Bulletin 118 basins + stream gages. - searchDrinkingWaterSystems ⭐ ~5K SABL polygons. county UPPERCASE - searchGroundwaterBasins ⭐ ~515 DWR Bulletin 118 basin/subbasin polygons. NO county - searchStreamGages ~2.6K USGS+DWR+local. Filter hasFlow/hasStage/gageStatus upstream quirks: Multi-host — gispublic.waterboards.ca.gov (SWRCB native) for Drinking Water + StreamGages; utility.arcgis.com (DWR utility map) for Bulletin 118. SWRCB Drinking Water OWNER_TYPE_CODE has trailing space ('L ', 'P ' etc) — handler matches both forms. Bulletin 118 is published by DWR, exposed here for one-stop water context.