Mariposa County, CA Outdoor Lighting: Light Trespass (2026)

Light trespass — unwanted light spilling from one property onto another — is not separately regulated in Mariposa County's currently adopted zoning code (Title 17, Chapter 17.108). The County's Development Code update would change this: the September 2024 draft Section 17.46 'Outdoor Light and Glare' requires that exterior lights be shielded so as not to spill light off-site. Specifically, the draft provides that 'Exterior lights used to illuminate a side of a building or wall shall be shielded to prevent the light from shining off of the surface intended to be illuminated,' and that structure-mounted and security lighting 'shall have full cutoff fixtures with the light source fully shielded and shall not direct light into the sky, adjacent properties, public easements, or rights-of-way.' The draft also bans 'blinking, flashing, high-intensity or bright lights' and requires that exterior lighting not be located where it constitutes a hazard to vehicle traffic on adjacent roads. Because the entire county is unincorporated, these standards (once adopted) would apply countywide. Until the update is adopted, a neighbor bothered by light trespass generally relies on California nuisance law (Civil Code 3479) and the County's discretionary project review rather than a numeric lighting standard. California has no statewide residential light-trespass limit.