← Impaired waters

Waterbody profile

Official Water Board record · 2026 cycle

Cape Mendocino HU, Mattole River HA, Mattole River Watershed

Waterbody ID (WBID)
CAR1123007219980708151559
County / counties
Humboldt, Mendocino
Regional Water Board
Regional Board 1 - North Coast 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
SedimentSediment168383List on 303(d) list (TMDL required list)Revised5A TMDL still requiredLow
Sedimentation/SiltationSediment70381Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)Original5B Addressed by USEPA-approved TMDLMattole Sediment
Specific ConductivitySALINITY/TOTAL DISSOLVED SOLIDS/CHLORIDES/SULFATES162999List on 303(d) list (TMDL required list)Revised5A TMDL still requiredLow
Temperature, waterOther Cause158446Do Not Delist from 303(d) list (being addressed with USEPA approved TMDL)Revised5B Addressed by USEPA-approved TMDLMattole Temperature

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
Sep 16, 2026, 10:56 PM UTC
Waterbody ID
CAR1123007219980708151559
CALWNUM
1112.300101, 1112.300103, 1112.300202, 1112.300301, 1112.300402, 1112.300502, 1112.300503, 1112.300504, 1112.300601, 1112.300701
WBD code
180101070201, 180101070202, 180101070203, 180101070204, 180101070205, 180101070206, 180101070207, 180101070208, 180101070209
Geometry
Official Water Board GIS (CA_WATERBOARDS_GIS_FINAL_2026)

Location

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

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Watershed
Assessed size
694.37 Miles

Derived facility associations

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

Derived
Baker Creek Quarry

Whitethorn · Notice of Intent · 0.14 km away

derived_nearby_in_watershed

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.