Arroyo Las Positas

Waterbody ID (WBID): CAR2043008020010905115005
County / counties: Alameda
Regional Water Board: Regional Board 2 - San Francisco Bay Region
Waterbody type: River & Stream
Condition category: Category 5 — 303(d) listed, TMDL required
Integrated Report cycle: 2026

303(d) listings (7)

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	150849	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Benthic Community EffectsOther Cause	154220	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
ChlorideSALINITY/TOTAL DISSOLVED SOLIDS/CHLORIDES/SULFATES	141699	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
DiazinonPesticides	141706	Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)	Revised	5B — Addressed by USEPA-approved TMDL	San Francisco Bay Urban Creeks Diazinon	—
EutrophicationNutrients	151285	Do Not Delist from 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
pHOther Cause	141720	List on 303(d) list (TMDL required list)	Revised	5A — TMDL still required	—	Low
Temperature, waterOther Cause	141726	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: CAR2043008020010905115005
CALWNUM: 2204.300602, 2204.300900
WBD code: 180500040202, 180500040203, 180500040302
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: 15.3 Miles

Facilities with an NAL exceedance for a listed pollutant (3)

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

Gillig LLC2 01I027313

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

LSI Recyclable Mtrl Trans Fac2 01I022697

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

Vintage 99 Label MFG Inc2 01I029068

pH · most recent exceedance RY 2022 · 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

Abayla Contracting Services Inc

Livermore · No Exposure Certification · 0.59 km away

derived_nearby_in_watershed