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

The San Diego County Light Pollution Code (County Code of Regulatory Ordinances, Division 59, commencing at Section 59.101, as amended by Ordinance 9716) is designed to protect the Palomar and Mount Laguna observatories from light pollution that harms astronomical research. Section 59.104 defines Zone A as the circular area 15 miles in radius centered on each observatory, and Zone B as the rest of the unincorporated county. The code classifies outdoor lighting into Class I (color-critical uses like signs and recreation), Class II (walkways, roadways, parking lots, security), and Class III (decorative/landscape). Section 59.105 sets lamp and shielding requirements: low-pressure sodium fixtures must be fully shielded in both zones; non-low-pressure-sodium fixtures above 4,050 lumens are prohibited in Zone A and generally restricted in Zone B; and lower-output fixtures must be fully shielded or limited. 'Fully shielded' (Section 59.104.k) means the fixture is constructed and mounted so no light is emitted above the horizontal plane. Section 59.107 requires all Class I lighting and all Class III lighting to be off between 11:00 p.m. and sunrise, with limited exceptions (e.g., billboards until midnight, areas actually in use). Permanent exemptions in Section 59.108 cover fixtures legally installed before January 18, 1985, fossil-fuel lights, federal/state facilities, holiday decorations, and flag illumination.