Contra Costa County, CA Outdoor Lighting: Light Trespass (2026)

Glare and light spillover are addressed in unincorporated Contra Costa County through general zoning nuisance provisions in Ordinance Code Title 8 and through project-specific conditions of approval on discretionary permits. Commercial, industrial, and multi-family residential developments typically must demonstrate that illumination at the property line does not exceed 0.5 foot-candles onto adjacent residential parcels, and that fixtures are fully shielded to prevent direct light from being visible off-site. CEQA review (under the California Environmental Quality Act) often requires a photometric lighting plan as part of project approval, particularly for projects near residential areas, rural communities, or Mt. Diablo State Park. Residential light trespass — such as a floodlight illuminating a neighbor's bedroom window or a landscape lighting installation directed across the property line — can be cited as a nuisance under Ord. Code Chapter 14-6 (general nuisance) or Title 8 zoning standards, with enforcement through DCD Code Enforcement. Auto dealerships, sports fields, and parking lots are subject to specific conditions limiting hours of full illumination and requiring dimming after closing. Complaints should be documented with photographs at night, written records of occurrences, and submitted to Code Enforcement. Reasonable security lighting with motion sensors is generally permitted.