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

Division C12 of the Santa Clara County Code includes outdoor lighting standards adopted specifically to preserve dark skies for the University of California Lick Observatory on Mount Hamilton, one of the premier professional observatories in the United States. Within the Mount Hamilton lighting zone, generally extending 10 miles from the observatory, all new permanent exterior lighting must be fully shielded so that no direct light is emitted above the horizontal plane. Lamp types are restricted to narrow-spectrum sources such as low-pressure sodium or amber LED at color temperature below 2700 Kelvin, and total outdoor lumens per parcel are capped. Countywide, outdoor lighting on new construction must be full cutoff with lamps concealed from view beyond the property line. Motion-activated security lighting above 1800 lumens must turn off automatically within 6 minutes. Wall-washing, uplighting of buildings, and landscape lighting pointed upward are restricted. Athletic field lighting requires specific approval and must use curfew controls after events. International Dark-Sky Association certifications are recognized. Violations are handled by Code Enforcement with notice and opportunity to correct, and chronic violations can be fined under Division B28 up to 1000 dollars per day. Festival and holiday lighting is generally exempt for temporary periods.