Nicasio Reservoir

Waterbody ID (WBID): CAL2011301220050519182548
County / counties: Marin
Regional Water Board: Regional Board 2 - San Francisco Bay Region
Waterbody type: Lake & Reservoir
Condition category: Category 5 — 303(d) listed, TMDL required
Integrated Report cycle: 2026

303(d) listings (1)

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
MercuryMetals	151594	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: CAL2011301220050519182548
WBD code: 180500050102
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: 862.46 Acres

Derived facility associations

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

Derived

Nicasio Rock Quarry Lafranchi Quarry

Nicasio · Notice of Intent · 0.08 km away

derived_nearby_in_watershed

Derived by California Stormwater Intelligence

West Marin Compost

Nicasio · Notice of Intent

derived_watershed_association

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.