Twain Harte, CA Outdoor Lighting: Light Trespass (2026)

Light trespass - exterior light spilling onto a neighboring property - is addressed in unincorporated Tuolumne County through the lighting provisions of the County's Title 17 Objective Site and Design Standards. The lighting spill standard states that lighting shall not spill beyond the intended area and shall be directed away from adjacent structures to minimize light spill, and that lighting of outdoor service, loading, and storage areas shall not be visible from the street or adjacent properties. The companion design-and-placement standard reinforces this by requiring that lighting be recessed or hooded, downward-directed, and located to illuminate only the intended area, with exposed bulbs and colored bulbs or lenses prohibited. For common areas in larger residential and mixed-use projects, fixtures must be fully shielded, restrain light to at least 30 degrees below the horizontal plane, and be arranged so the light will not shine directly onto adjacent residentially zoned land, with uplighting prohibited. These standards apply most directly to projects subject to the County's objective design review (multi-unit, mixed-use, and design-review-district projects). For ordinary residential light-spill disputes between neighbors, the County's general nuisance authority and code-enforcement process provide a backstop, and persistent glare or spill can be pursued as a nuisance. Anyone installing new exterior lighting should aim fixtures downward, shield them, and confirm the light footprint stays on their own parcel. Verify the applicable standards for a particular project with the Community Development Department.