Sereno del Mar, CA

All fireworks, including 'Safe and Sane' items, are illegal in unincorporated Sonoma County. Possession, sale, storage, use, or discharge is prohibited except for State-licensed public displays. Property owners and renters can be cited as social hosts when fireworks are set off on their property. Fines reach up to $1,000 per violation, and the entire county is in a CalFire-designated wildfire-prone area following the 2017 Tubbs, 2019 Kincade, and 2020 Glass/LNU fires.

Unincorporated Sonoma County allows accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) ministerially in any zoning district that permits a single-family or multi-family primary dwelling, under Sonoma County Code Section 26-88-060 (ADUs) and Section 26-88-061 (JADUs). The current inland ADU ordinance was adopted by the Board of Supervisors on December 5, 2023 and took effect January 4, 2024, implementing California Government Code Sections 65852.2 and 65852.22 along with the suite of state ADU bills (AB 68, SB 13, AB 881, AB 670, AB 671, SB 897, AB 2221, AB 1033, SB 1211, AB 2533). Detached new-construction ADUs are capped at 1,200 square feet, attached ADUs at 50% of the primary dwelling or 1,200 square feet (whichever is less, but at least 800 sq ft must be allowed), and JADUs at 500 square feet contained within an existing or proposed single-family dwelling. State law guarantees an 18-foot height for detached ADUs (16 feet plus 2 feet for roof pitch) on most lots, 4-foot side and rear setbacks, no minimum lot size, and no owner-occupancy requirement for ADUs permitted between January 1, 2020 and January 1, 2025. JADUs require the owner to live in either the primary dwelling or the JADU and a recorded deed restriction. ADUs and JADUs in unincorporated Sonoma County may not be rented for terms shorter than 30 days, and properties in the State Responsibility Area (SRA), Local Responsibility Area Very High Fire Hazard Severity Zone, or Wildland-Urban Interface (WUI) must meet California Building Code Chapter 7A ignition-resistant construction and PRC 4291 / Sonoma County defensible space requirements - heightened standards adopted in response to the 2017 Tubbs Fire, 2019 Kincade Fire, and 2020 Glass Fire that destroyed thousands of homes countywide. The County has not adopted an AB 1033 condominium-conversion ordinance, so ADUs in unincorporated Sonoma County cannot currently be sold separately from the primary dwelling.

Sonoma County's water supply comes primarily from the Russian River system managed by Sonoma Water (Sonoma County Water Agency), which serves most cities and special districts in the county. Unincorporated areas are served by smaller mutual water companies, private wells, and county service areas. Sonoma County Code Chapter 25B requires private wells to meet permit and metering standards, and the county Board of Supervisors and Sonoma Water issue coordinated drought-stage declarations that trigger outdoor watering bans, day-of-week schedules, and well-pumping restrictions. The state's MWELO (Cal. Code Regs. Title 23, §490) applies to landscape projects of 500 sq ft or more in unincorporated Sonoma County.

Sonoma County is a North Bay California jurisdiction with extensive riverine flood hazards along the Russian River, Laguna de Santa Rosa, Mark West Creek, Santa Rosa Creek, and Petaluma River. Floodplain development in the unincorporated county is regulated under Chapter 7B (Flood Damage Prevention) of the Sonoma County Code, together with the F1 Floodway Combining District (Chapter 26 Article 56) and F2 Floodplain Combining District (Chapter 26 Article 58). The County participates in the National Flood Insurance Program (NFIP) and adopts FEMA Flood Insurance Rate Maps; Permit Sonoma's Engineering and Construction Division enforces elevation, freeboard, and Elevation Certificate requirements consistent with California Government Code section 65302 floodplain mapping duties.