Alamitos Bay

Waterbody ID (WBID): CAB4051200020070329124415
County / counties: Los Angeles, Orange
Regional Water Board: Regional Board 4 - Los Angeles Region
Waterbody type: Bay & Harbor
Condition category: Category 5 — 303(d) listed, TMDL required
Integrated Report cycle: 2026

303(d) listings (6)

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
CopperMetals	135883	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
DDD (Dichlorodiphenyldichloroethane)Pesticides	150069	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
DDT (Dichlorodiphenyltrichloroethane)Pesticides	150071	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Indicator BacteriaPathogens	171741	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Los Cerritos Channel and Estuary, Alamitos Bay, and Colorado Lagoon Indicator Bacteria TMDL	—
Oxygen, DissolvedNutrients	135904	Do Not Delist from 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
PCBs (Polychlorinated biphenyls)Toxic Organics	135908	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low

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: CAB4051200020070329124415
CALWNUM: 4405.120000, 4405.150000, 4412.100000, 4801.110000
WBD code: 180701060606, 180701060702, 180701060703, 180702010002
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: 327.52 Acres

Facilities with an NAL exceedance for a listed pollutant (13)

Geographically associated industrial stormwater facilities whose reported results exceeded an Industrial General Permit Numeric Action Level for a pollutant this waterbody is listed for.

Derived

AltAir Paramount Facility4 19I027557

Copper · most recent exceedance RY 2022 · association: derived watershed association

Cavotec USA8 30I024632

Copper · most recent exceedance RY 2019 · association: derived watershed association

Certified Alloy Products Inc4 19I005554

Copper · most recent exceedance RY 2021 · association: derived watershed association

Downey4 19I028471

Copper · most recent exceedance RY 2025 · association: derived watershed association

Hyatt Die Casting8 30I000211

Copper · most recent exceedance RY 2025 · association: derived watershed association

Marina Shipyard4 19I004977

Copper · most recent exceedance RY 2016 · association: derived nearby in watershed

Miller Castings Inc4 19I022672

Copper · most recent exceedance RY 2025 · association: derived watershed association

Miller Castings Inc4 19I024769

Copper · most recent exceedance RY 2021 · association: derived watershed association

Pioneer Auto Wrecking4 19I018347

Copper · most recent exceedance RY 2019 · association: derived watershed association

Ship and Shore Environmental Inc4 19I028525

Copper · most recent exceedance RY 2022 · association: derived watershed association

Turbine Engine Components Tech4 19I016865

Copper · most recent exceedance RY 2021 · association: derived watershed association

Universal Molding Extrusion Co4 19I013881

Copper · most recent exceedance RY 2015 · association: derived watershed association

Virgin Orbit LLC4 19I027148

Copper · most recent exceedance RY 2020 · association: derived watershed association

This is derived co-occurrence between a calculated NAL comparison and the official 303(d) listing for this waterbody. An NAL exceedance triggers Exceedance Response Actions under the permit; it is not a violation and does not establish that any facility caused or contributed to this impairment.

Derived facility associations

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

Derived

1959

Los Angeles · No Exposure Certification

derived_watershed_association