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.