151 California Ave
Mill Valley 94941 · Almonte · Unincorporated Marin · Coordinates: 37.88778, -122.52963
Executive Verdict · Public-Records Synthesis
Zoned R1-B1 in Unincorporated Marin with likely ADU & SB 9 infill eligibility and zero mapped flood, fire, or fault hazard overlaps; benchmark value $2,157,000 ($1,898,000–$2,416,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B1 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 6,665 sq ft lot. Local precedent is active with 4 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$59,520 contributory est.)
Public building records show issued construction/renovation work on this parcel (6 total permits, latest Feb 28, 2026).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! Mapped flood awareness zone (Zone X: minimal flood hazard)
all of the lot of the parcel intersects Zone X: minimal flood hazard. Outside mandatory federal SFHA insurance rules, but check local drainage and finished-floor requirements.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! 6 slow or stalled nearby projects within ½ mile
Closest lead: Accessory dwelling unit at 131 Yale Ave A (180 ft E, issued). Inspect timeline history before assuming near-term completion.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · HCD APR (½-mile radius)
- ! Year 1 Prop 13 tax reset (~$25,256/yr at $2,157,000)
Sale triggers reassessment to 1.00% base + ~0.15% voter debt (~$2,105/mo). Confirm exact Mello-Roos / CFD special assessments on the county tax bill.
Source: CA Const. Art. XIIIA (Prop 13) · County Tax Collector
Parcel & Assessor
- Lot size:
- 6,665 sq ft (0.15 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 151 CALIFORNIA AVE
Zoning & Land Use
R1-B1 — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B1 (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B1, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B1, a single-family residential zone. The lot is 6,665 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- Not in a State-mapped fire hazard severity zone
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0469F, effective March 16, 2016
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,898,000 – $2,416,000 · Status: Off market
HUD Small Area FMR (ZIP 94941) · FY 2026
Studio $2,730 · 1BR $3,270 · 2BR $3,960 · 3BR $5,060 · 4BR $5,240
Developments Deserving Closer Investigation & Active Area Builders
- Accessory dwelling unit at 131 Yale Ave A (Issued)180 ft E
Active in "Issued" for 4.8 yr (first record Jan 19, 2022) with no new permit activity recorded in 3.4 yr. High-impact scale (1 housing unit, $1,000,000 declared valuation across 1 permit).
- New commercial building at 100 Harvard Ave (Issued)0.19 mi W
Active in "Issued" for 23 mo (first record Dec 26, 2024) with no new permit activity recorded in 18 mo. High-impact scale ($6,500,000 declared valuation across 1 permit).
- New home at 217 Cleveland Ave (Issued)0.2 mi S
Active in "Issued" for 9.7 yr (first record Feb 21, 2017) with no new permit activity recorded in 2.3 yr. High-impact scale (1 housing unit, $875,000 declared valuation across 1 permit).
- 2 new homes (Issued)0.41 mi NW
Active in "Issued" for 5.7 yr (first record Mar 1, 2021) with no new permit activity recorded in 5.7 yr. High-impact scale (2 housing units, 1 deed-restricted affordable across 0 permits).
Entity-resolved builders & contractors in ½ mile: Reliable Construction (1 on parcel, 1 in ½ mi · Remodel / interior alteration); Solarcraft Services (1 on parcel, 1 in ½ mi · Solar / battery storage); Wedge Roofing (1 on parcel, 1 in ½ mi · Roof replacement); Denys Ivanov (1 on parcel, 1 in ½ mi · HVAC / heat pump); Plumbing Pure (1 on parcel, 1 in ½ mi · Plumbing / water heater / sewer).
Permit & Project History on This Parcel (6 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B46045 | EV charger | Issued | Iss. Feb 28, 2026 | $1,200 | EV Charging Station; With Electronic Inspection |
| B43968 | HVAC / heat pump | Issued | Iss. Sep 25, 2025 | $12,000 | AC installation with existing gas furnace At the same location — Mechanical Appliance |
| B44002 | Solar / battery storage | Issued | Iss. Sep 23, 2025 | $71,161 | (NEW) FLUSH MOUNTED PV SYSTEM WITH (NEW) BATTERY STORAGE, GRID TIED MICROINVERTERS, (NEW) MAIN SERVICE PANEL |
| B42909 | Roof replacement | Issued | Iss. Jun 26, 2025 | $58,650 | Single Area Only- Remove existing surface to receive new roof. Prepare existing sheathing for new roof. Install HDZ RS L… |
| 178950 | Remodel / interior alteration |