← Impaired waters

Waterbody profile

Official Water Board record · 2026 cycle

Oso Creek (lower)

Waterbody ID (WBID)
CAR9012000020010831154628
County / counties
Orange
Regional Water Board
Regional Board 9 - San Diego 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 / stressorDecision IDFinal listing decisionDecision statusTMDL requirement statusTMDL projectTMDL priority
NitrogenNutrients127529Do Not Delist from 303(d) list (TMDL required list)Revised5A TMDL still requiredLow
PhosphorusNutrients111142Do Not Delist from 303(d) list (TMDL required list)Revised5A TMDL still requiredLow
SeleniumMetals111143Do Not Delist from 303(d) list (TMDL required list)Revised5A TMDL still requiredLow
ToxicityTotal Toxics111146Do Not Delist from 303(d) list (TMDL required list)Revised5A TMDL still requiredLow

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
CAR9012000020010831154628
CALWNUM
90120000
Geometry
Official Water Board GIS (CA_WATERBOARDS_GIS_FINAL_2026)

Location

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

Loading map…
Watershed
Assessed size
12.39 Miles

Derived facility associations

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

Derived
3A Treatment Plant

Laguna Niguel · Notice of Intent · 0.25 km away

derived_receiving_water

Derived by California Stormwater Intelligence

Oso Parkway

Laguna Hills · Notice of Non-Applicability · 0.26 km away

derived_receiving_water

Derived by California Stormwater Intelligence

Oso Parkway Crushing Facility and Batch Plant

Mission Viejo · Notice of Intent · 0.24 km away

derived_receiving_water

Derived by California Stormwater Intelligence

San Juan Capistrano Equestrian Center

San Juan Capistrano · Notice of Intent · 0.49 km away

derived_receiving_water

Derived by California Stormwater Intelligence

USPS Mission Viejo VMF

Mission Viejo · No Exposure Certification · 0.58 km away

derived_receiving_water

Derived by California Stormwater Intelligence

Facility records are official Industrial General Permit registrations, but the association between a facility and this waterbody is derived geographically (proximity or shared HUC12 subwatershed) and is not a Water Board receiving-water determination. Where a permit carries a Water Board-stated TMDL requirement naming this water, it is listed separately above.