Arroyo Seco Reach 1 (LA River to West Holly Ave.)

Waterbody ID (WBID): CAR4051501019990202132906
County / counties: Los Angeles
Regional Water Board: Regional Board 4 - Los Angeles Region
Waterbody type: River & Stream
Condition category: Category 4a — TMDL completed
Integrated Report cycle: 2026

303(d) listings (2)

Each row is one official listing decision from Appendix A of the Final 2026 California Integrated Report. Source terminology is preserved as published.

Pollutant / stressor	Decision ID	Final listing decision	Decision status	TMDL requirement status	TMDL project	TMDL priority
Indicator BacteriaPathogens	150276	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Los Angeles River Pathogens (15)	—
TrashTrash	75547	List on 303(d) list (being addressed by USEPA approved TMDL)	Original	5B — Addressed by USEPA-approved TMDL	Los Angeles River Trash (12)	—

Source & provenance

Agency: California State Water Resources Control Board
Report: Final 2026 California Integrated Report
Dataset: Appendix A — 2026 303(d) List of Impaired Waters
Imported: Aug 21, 2026, 12:44 AM UTC
Waterbody ID: CAR4051501019990202132906
CALWNUM: 40515010
Geometry: Official Water Board GIS (CA_WATERBOARDS_GIS_FINAL_2026)

View official Water Board fact sheet ↗Download Appendix A source file ↗

Location

Official 2026 Water Board geometry. Demonstration facility markers are shown for context only.

Loading map…

Watershed: —
Assessed size: 5.22 Miles

Derived facility associations

Industrial stormwater facilities geographically associated with this waterbody. These are derived spatial associations, not Water Board findings.

Derived

Bmw Mercedes World Inc

Los Angeles · Notice of Intent · 0.32 km away

derived_receiving_water