Merced

Merced County is a Central Valley agricultural county (population ~290,000) along the State Route 99 corridor between Stanislaus County (north) and Madera County (south). The county seat is Merced city, home of UC Merced (the newest UC campus, opened 2005). Six incorporated cities: Merced, Atwater, Livingston, Gustine, Los Banos, and Dos Palos. Extensive unincorporated agricultural footprint plus the unincorporated communities of Hilmar-Irwin, Winton, Cressey, Snelling, Planada, Le Grand, Santa Nella, Volta, Stevinson, El Nido, and South Dos Palos. The county Board of Supervisors administers ADUs in unincorporated areas under 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). The county code addresses ADUs and JADUs through ministerial 60-day review consistent with state preemption. Merced County's permitting environment is dominated by Williamson Act agricultural-preserve coverage (the county is one of the most heavily Williamson-Act-covered counties in California - well over half of the unincorporated land area is under contract), Central Valley irrigated-agriculture parcel patterns, and dairy/feedlot operational siting that creates ADU placement constraints near commercial agricultural operations.

• Merced County Code Title 18 - 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. Gov't Code Sec. 51200 et seq. (Williamson Act)

State-floor overlay: California state ADU preemption applies in full. AB 1033 condo-conversion election is at the county's option and Merced 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). Williamson Act parcels are subject to the Act's 'compatible use' framework which permits ADUs (residential structures supporting the principal agricultural use) but constrains commercial-scale residential development.

Merced County overlays of consequence: Williamson Act agricultural preserve coverage on a majority of unincorporated parcels (a defining characteristic of the county); SJVAPCD federal nonattainment area for PM2.5 and ozone; SGMA-overdrafted groundwater subbasins (Merced, Chowchilla) under critically-overdrafted designation; FEMA SFHA along the San Joaquin River, Merced River, Mariposa Creek, and tributary drainages; CAL FIRE State Responsibility Area along the eastern foothills (very high FHSZ in the Sierra foothill toe); the San Luis National Wildlife Refuge Complex (San Luis NWR, Merced NWR, Kesterson NWR) on the western county; the Merced National Wildlife Refuge winter-grounds for sandhill cranes; and UC Merced campus / Merced Vernal Pools and Grassland Reserve (UC Natural Reserve System) on the eastern flank near the Lake Yosemite area.

• Williamson Act / California Land Conservation Act preserve contracts
• San Joaquin Valley Air Pollution Control District - federal nonattainment
• Sustainable Groundwater Management Act - Merced and Chowchilla subbasins (critically overdrafted)
• FEMA SFHA - San Joaquin, Merced, Chowchilla River drainages
• CAL FIRE State Responsibility Area - eastern foothills
• San Luis NWR Complex / Merced NWR (federal wildlife refuges)

The Merced County Department of Community and Economic Development - Planning Division issues ADU permits in unincorporated areas. Practical permitting frictions: Williamson Act compatibility review (the dominant constraint - much of unincorporated Merced County is under agricultural preserve contracts), San Joaquin Valley Air Pollution Control District (SJVAPCD) air-quality requirements (the SJV is a federal nonattainment area for PM2.5 and ozone), Sustainable Groundwater Management Act (SGMA, Water Code Sec. 10720 et seq.) groundwater-basin restrictions affecting well permits in critically-overdrafted subbasins (Merced is in the Merced and Chowchilla SGMA subbasins, both critically overdrafted), CAL FIRE State Responsibility Area along the eastern foothills toward Mariposa County, and dairy/feedlot operational-setback rules that interact with ADU placement near commercial operations.