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

Light trespass - light from one property spilling onto another or into the street - is directly addressed in Colusa County Code Section 44-3.30.010 (Lighting Standards), part of the Outdoor Lighting section. The Nuisance Prevention standard provides that 'All outdoor lighting shall be located, adequately shielded, and directed such that no direct light falls outside the property line, or into the public right-of-way,' as illustrated in the code's Light Trespass figure (Figure 44-3.30-1). The Shielding standard requires that, except where exempt, all outdoor lighting be 'constructed with full shielding and/or recessed to reduce light trespass to adjoining properties and to reduce illumination of the night sky,' with each fixture 'directed downward and away from adjoining properties and public rights-of-way, so that no light fixture directly illuminates an area outside of the site.' Fixtures located higher than 6 feet above the ground must have shielding that limits the cone of direct illumination to 60 degrees or less. Accent up-lighting of architectural features is allowed only with low-intensity lamps producing 'no glare or light trespass.' These standards apply to outdoor lighting in residential, commercial, industrial, and special-purpose zones (and adjacent lighting), excluding publicly owned facilities and rights-of-way (Sec. 44-3.30). Colusa County does not set a numeric footcandle limit at the property line; the operative test is full shielding, downward direction, and no direct light crossing the property line. Persistent spillover lighting may be addressed as a nuisance; report concerns to Colusa County Planning & Building.