— Sources

Where the data comes from.

Every number on Catchment is an observation someone else made first. This page names the upstream sources we ingest today, when each one was last refreshed on production, and where to read their own documentation. Full per-record provenance (source_manifest[] with cite_id) is a post-alpha upgrade — for now, this table is the honest minimum.

Source	What we use it for	Last refreshed (prod)
CDEC California Data Exchange Center	Daily operational data for the 15 California reservoirs tracked on the map (storage, elevation, release, inflow).	—
USBR HydroData Upper Colorado Region	Daily operations for Colorado Route B reservoirs and strategic gages (Hoover, Glen Canyon, Navajo, Flaming Gorge, Crystal, Lees Ferry, …).	—
EPA SDWIS via ORD community water system service-area boundaries	Community Water System (CWS) polygons on the map — utility names, population served, ownership, verification status.	—
ECHO NPDES EPA Enforcement and Compliance History Online — NPDES permits (major facilities)	Wastewater treatment plant locations and permit data (~6,500 major facilities). Point geometries spatially linked to CWS service areas.	—
ECHO SDWA EPA Enforcement and Compliance History Online — Safe Drinking Water Act public water systems	Drinking-water system interconnections — who buys water from whom (~10–15K wholesale purchase edges).	—
EPA FRS Facility Registry Service — geometry for regulated environmental facilities	Coordinates and geometry tier classification for drinking-water treatment plants, intakes, storage, and wells.	—
EPA CERCLIS / SEMS Superfund Enterprise Management System — National Priorities List hazardous waste sites	NPL Superfund contamination sites with groundwater pathway, spatially linked to CWS service areas they threaten (~540 sites).	—

If a refresh cell shows an em dash, production returned no generated_at for that source — see the publish log on the next deploy.