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

Riverside County Ordinance No. 655 regulates light pollution to protect astronomical research at Palomar Observatory. It establishes two zones centered on the observatory: Zone A is the circular area within a 15-mile radius (Sec. 4.H), and Zone B is the ring between 15 and 45 miles (Sec. 4.I). The ordinance classifies fixtures and limits them by zone. Low-pressure sodium lamps are favored and allowed in both zones; many higher-output non-low-pressure-sodium lamps are prohibited in Zone A and restricted in Zone B. "Fully shielded" fixtures must project all light rays below the horizontal plane through the lowest point of the fixture (Sec. 4.J), and "partially shielded" fixtures must project at least 90% of light below that horizontal plane (Sec. 4.K). Curfew provisions require Class I (general/color-rendition) lighting to be off between 11:00 p.m. and sunrise, with exceptions for on-premise signs and active recreation; Class III (decorative) lighting must be off between 11:00 p.m. and sunrise (Sec. 8). Class II (parking/security) lighting may remain on all night. Non-low-pressure-sodium street lights on private roadways and advertising searchlights are prohibited (Sec. 8). The ordinance is not intended to restrict low-pressure sodium security lighting of single-family homes, and exempts pre-existing fixtures, fossil-fuel lights, and holiday decorations (Sec. 9). Temporary exemptions up to 45 days per year are available with a $50 filing fee (Sec. 10).