Calleguas Creek Reach 7 (Arroyo Simi)

Waterbody ID (WBID): CAR4036200020000228103510
County / counties: Ventura
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 (22)

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
AmmoniaNutrients	150428	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Nitrogen (1)	—
BifenthrinPesticides	137308	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
BoronMetals	137263	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Boron/Sulfate/TDS (4)	—
ChlordanePesticides	137265	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Historic Pesticides (5)	—
ChlorideSALINITY/TOTAL DISSOLVED SOLIDS/CHLORIDES/SULFATES	137266	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Boron/Sulfate/TDS (4)	—
ChlorpyrifosPesticides	137270	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Toxicity (2)	—
CopperMetals	137273	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Metals (6)	—
CyfluthrinPesticides	137315	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
CypermethrinPesticides	137309	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
DDT (Dichlorodiphenyltrichloroethane)Pesticides	149487	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek PCBs (7)	—
DeltamethrinPesticides	137316	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Indicator BacteriaPathogens	68267	Do Not Delist from 303(d) list (TMDL required list)	Original	5A — TMDL still required	—	Low
IronMetals	137284	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Nitrate/Nitrite (Nitrite + Nitrate as N)Nutrients	137290	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Nitrogen (1)	—
PermethrinPesticides	137317	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
PyrethroidsPesticides	137307	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Sedimentation/SiltationSediment	69775	List on 303(d) list (TMDL required list)	Original	5A — TMDL still required	—	Low
SeleniumMetals	137297	List on 303(d) list (being addressed by USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Metals (6)	—
SulfatesToxic Inorganics	137299	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Boron/Sulfate/TDS (4)	—
Total Dissolved SolidsSALINITY/TOTAL DISSOLVED SOLIDS/CHLORIDES/SULFATES	137301	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Boron/Sulfate/TDS (4)	—
ToxicityTotal Toxics	137304	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	Calleguas Creek Toxicity (2)	—
TrashTrash	72109	List on 303(d) list (TMDL required list)	Original	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: CAR4036200020000228103510
CALWNUM: 4408.220000, 4408.270000
WBD code: 180701030101, 180701030102
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: 14.16 Miles

Facilities with an NAL exceedance for a listed pollutant (11)

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

Ensign Bickford A and D Company4 56I022536

Copper · most recent exceedance RY 2024 · association: derived watershed association

GI Industries4 56I004024

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

Pre Con Products4 56I003953

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

PW Gillibrand Co Simi Valley4 56I003605

Nitrate/Nitrite (Nitrite + Nitrate as N) · most recent exceedance RY 2025 · association: derived watershed association

Simi Valley4 56I028252

Iron, Nitrate/Nitrite (Nitrite + Nitrate as N) · most recent exceedance RY 2024 · association: derived nearby in watershed

Simi Valley Landfill4 56I005786

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

Simi Valley Ready Mix4 56I012014

Iron · most recent exceedance RY 2018 · association: derived nearby in watershed

Spragues Ready Mix4 56I002349

Iron · most recent exceedance RY 2017 · association: derived watershed association

Tapo Rock Sand4 56I004036

Nitrate/Nitrite (Nitrite + Nitrate as N) · most recent exceedance RY 2016 · association: derived watershed association

Vanderhorst Brothers Inc4 56I017880

Nitrate/Nitrite (Nitrite + Nitrate as N) · most recent exceedance RY 2015 · association: derived nearby in watershed

Vista Professional Outdoor Lighting Bld 24 56I028935

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

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

133art LLC

Simi Valley · No Exposure Certification

derived_watershed_association