Waterbody profile

Official Water Board record · 2026 cycle

Walnut Creek Wash (Drains from Puddingstone Res)

Waterbody ID (WBID): CAR4053100019980918112433
County / counties: Los Angeles
Regional Water Board: Regional Board 4 - Los Angeles Region
Waterbody type: River & Stream
Condition category: Category 5 — 303(d) listed, TMDL required
Integrated Report cycle: 2026

303(d) listings (4)

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
Benthic Community EffectsOther Cause	77230	Do Not Delist from 303(d) list (TMDL required list)	Original	5A — TMDL still required	—	Low
CopperMetals	138770	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	San Gabriel River Metals (39)	—
Indicator BacteriaPathogens	150343	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	San Gabriel River Coliform (45)	—
pHOther Cause	170611	Do Not Delist from 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: CAR4053100019980918112433
CALWNUM: 4405.2
WBD code: 180701060402, 180701060601
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.

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Watershed: —
Assessed size: 13.92 Miles

Facilities with an NAL exceedance for a listed pollutant (22)

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

Allan Co4 19I000752

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

Athens Services Vincent4 19I021980

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

Award Metals Inc4 19I009949

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

Bassett USD Bus Maintenance Facility4 19I017980

pH · most recent exceedance RY 2018 · association: derived watershed association

Breeders Choice Pet Foods LLC4 19I029855

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

Burrtec Waste Services LLC4 19I018755

pH · most recent exceedance RY 2018 · association: derived watershed association

CA Amforge4 19I001029

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

California Expanded Metal Product4 19I009657

pH · most recent exceedance RY 2015 · association: derived nearby in watershed

Cascade Steel Rolling Mills Inc4 19I004254

Copper · most recent exceedance RY 2020 · association: derived receiving water

CLEANTECH4 19I027458

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

Complete Metal Design Inc4 19I027490

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

Covina Valley Unified Sch D4 19I017968

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

Custom Alloy Sales Inc4 19I001777

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

Discount Auto Wreckers4 19I013758

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

G I Trucking Co dba Estes West4 19I018109

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

Goldencorr Sheets LLC4 19I029471

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

Los Altos Food Products Inc4 19I026474

pH · most recent exceedance RY 2025 · association: derived nearby in watershed

Mag Parts4 19I001038

pH · most recent exceedance RY 2016 · association: derived watershed association

Organic Milling Inc4 19I025302

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

S and S Foods LLC4 19I024156

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

SA Recycling4 19I022544

Copper · most recent exceedance RY 2020 · association: derived receiving water

Tecomet Inc4 19I019285

Copper, pH · most recent exceedance RY 2019 · 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

5 Boys Precision Machining

Covina · No Exposure Certification

derived_watershed_association