Mariposa

Mariposa County is a Sierra Nevada foothill / gateway county (population ~17,000) with no incorporated cities - it is entirely unincorporated and administered by the County Board of Supervisors. The county seat is the unincorporated community of Mariposa town. Because there are no incorporated cities, the county ADU ordinance is the governing zoning code for 100% of parcels. Mariposa County encompasses the western half of Yosemite National Park (the federal inholding is exempt from county zoning) and the gateway communities (Mariposa, El Portal, Wawona inholdings, Fish Camp, Coulterville, Hornitos, Bootjack, Catheys Valley, Don Pedro, Greeley Hill, Midpines, Lake Don Pedro). The county code addresses ADUs and JADUs through ministerial 60-day review consistent with California Government Code Sec. 65852.2 and 65852.22 (state ADU preemption, as amended by AB 68/881, SB 13, AB 670/3182, AB 2221/SB 897, AB 976, and AB 1033). Practical permitting frictions are dominated by very high fire severity zone (FHSZ) coverage across nearly the entire county, septic/well dependence outside the small Mariposa Public Utility District (MPUD) service area, and steep-slope grading constraints in foothill terrain.

• Mariposa County Code Title 17 - Zoning, ADU/JADU provisions
• Cal. Gov't Code Sec. 65852.2 (Accessory Dwelling Units)
• Cal. Gov't Code Sec. 65852.22 (Junior Accessory Dwelling Units)
• Cal. Health & Safety Code Sec. 17920.3 (Substandard Housing)

State-floor overlay: California state ADU preemption applies in full. AB 1033 condo-conversion election is at the county's option and Mariposa County has not adopted it as of last check. AB 976 prohibits owner-occupancy mandates on detached ADUs through 2025 expiry. HCD oversight: any county ordinance amendment must be submitted to HCD within 60 days of adoption per Sec. 65852.2(h). The Yosemite National Park federal inholding (about 750,000 of the county's 953,000 acres, ~78% of land area) is outside county zoning entirely - federal in-park housing is governed by NPS concessioner agreements, not county code.

Mariposa County overlays of consequence: CAL FIRE Very High Fire Hazard Severity Zone (FHSZ) covers essentially the entire county within the State Responsibility Area; California WUI Chapter 7A ignition-resistant construction applies broadly; FEMA SFHA along the Merced River, Chowchilla River, and tributary drainages; Williamson Act agricultural preserve contracts cover much of the eastern Catheys Valley and Hornitos foothills; the Yosemite National Park federal inholding (the dominant land-area feature) falls outside county zoning entirely; Mariposa County Oak Woodland Conservation Ordinance governs oak woodland disturbance on parcels with significant oak canopy; Highway 140 (the all-year Yosemite gateway route along the Merced River) is a designated state scenic highway corridor with a wild-and-scenic river segment along the Merced through Briceburg.

• CAL FIRE State Responsibility Area / Very High FHSZ
• FEMA SFHA - Merced and Chowchilla River drainages
• Williamson Act agricultural preserve contracts
• California Scenic Highway System - SR-140 (Yosemite Gateway)
• Mariposa County Oak Woodland Conservation Ordinance
• Yosemite National Park federal inholding

The Mariposa County Planning Department issues all ADU permits in the county because every parcel outside Yosemite National Park is unincorporated. The Building Department handles plan check and inspections. Practical permitting frictions: very high fire severity zones (CAL FIRE State Responsibility Area covers essentially all of the county), Chapter 7A ignition-resistant construction documentation requirements, septic/well design review outside the small MPUD water/sewer service area in Mariposa town, steep-slope grading review in foothill terrain, oak woodland habitat considerations under the Mariposa County Oak Woodland Conservation Ordinance, and Yosemite gateway short-term-rental (STR) conditions of approval that may apply in Wawona, Fish Camp, and El Portal census-designated places where STR demand is highest. Mariposa County has had escalating tension with STR operators since the 2018-2022 surge in Yosemite-gateway vacation rentals; the Board of Supervisors has tightened STR registration but has NOT prohibited ADUs from STR use outright.