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

Light trespass - light spilling from one property onto another - is directly regulated by Mono County's Dark Sky Regulations in General Plan Chapter 23. Section 23.070(2) states that no outdoor lighting fixtures shall be installed, aimed, or directed to produce light that spills over into neighboring properties or the public right-of-way, and that light trespass is prohibited. This is reinforced by the shielding requirements of Section 23.050, which mandate full-cutoff luminaires that are downcast and fully shielded so that no light is emitted above the horizontal plane; the limited exceptions for fixtures of 100 lumens or less and 600 lumens or less both require that the lamp not be visible off-site and that no direct glare result. Together these provisions mean a property owner must aim and shield exterior fixtures - porch lights, security lights, floodlights, and landscape lighting - so the illumination stays on their own parcel. Section 23.010 frames the goal as preventing nuisances caused by unnecessary light intensity, direct glare, and light trespass. Existing nonconforming fixtures must be corrected when the property triggers compliance through design review, a conditional use permit, subdivision approval, or a building permit (Section 23.030). A neighbor experiencing light trespass can report it to Mono County Code Compliance.