Mono County, CA Outdoor Lighting: Dark Sky Rules (2026)

Mono County adopted comprehensive Dark Sky Regulations as Chapter 23 of the General Plan Land Use Element, reflecting the region's dark-sky values around Mono Lake and Eastern Sierra observation sites. Section 23.010 states the purpose: to promote a safe and pleasant nighttime environment, prevent nuisances from unnecessary light intensity, direct glare, and light trespass, and protect the ability to view the night sky. Section 23.050 requires new outdoor lighting to use full-cutoff luminaires with the light source downcast and fully shielded so no light is emitted above the horizontal plane, with narrow exceptions: fixtures of 100 lumens or less may use semi-translucent or frosted glass with opaque tops if the bulb is not visible off-site (23.050(5)(a)), and fixtures of 600 lumens or less may be partially shielded if the lamp is not visible off-site and no direct glare results (23.050(5)(b)). Section 23.070 prohibits mercury-vapor and low-pressure sodium lamps, unshielded floodlights, searchlights and laser-source lights (except emergencies), and blinking, flashing, moving, revolving, scintillating, flickering, changing-intensity, or changing-color lights. Existing fixtures must be brought into compliance when a property undergoes design review, a conditional use permit, subdivision approval, or a building permit for a new structure, modified exterior fixtures, or additions (Section 23.030). Applications must include an outdoor lighting plan.