La Plata County, CO Outdoor Lighting: Dark Sky Rules (2026)

Section 70-7 states its purpose plainly: standards for outdoor exterior lighting that assure the safety, utility and security of development and prevent night lighting from adversely affecting adjacent properties and neighborhoods. It applies to all new development requiring a building permit.

The core fixture rule is tied to lumens. Any outdoor fixture with an initial output of more than 2,000 lumens, which the code equates to a twenty-six (26) watt compact fluorescent or a one hundred (100) watt standard incandescent lamp, must be a full cut-off fixture as depicted in Figure 70-7. That covers road, parking area, security, walkway and building lighting. Mounting height tops out at 35 feet above finished grade. All lighting must be downward directed and cannot spill across property lines. Permanent lights that blink, flash or change in intensity are prohibited, except government-authorized traffic control devices and lights the Federal Aviation Administration requires. Nonresidential fixtures, including display lighting, go off after close of business unless needed for safety or security, and then the lighting drops to the minimum level necessary.

The exemptions are specific. Lighting whose primary purpose is the function or security of an agricultural use is exempt, but outdoor lighting of residential dwellings and accessory structures on the same property is not. Temporary decorations are exempt when displayed for no more than 30 consecutive days, up to no more than twice per year for a total of no more than 60 days in a calendar year. Aviation lighting is exempt, though heliport lighting must be off when the heliport is not in use. Temporary construction site lighting, lighting in the public right-of-way that principally illuminates streets, and lighting for the sole purpose of illuminating an American flag on agricultural and residential properties are also exempt.

Seasonal outdoor recreational facilities such as ball diamonds and playing fields are exempt from the full cutoff and pole height rules only if poles do not exceed 45 feet, illumination at the nearest interior setback line of a residential structure does not exceed 1 ½ foot candles, and all outdoor lights are extinguished by 10:00 p.m.

Multi-family dwellings and every nonresidential development application must include a lighting plan showing the lamps, wattage, height and location of devices, fixtures, shields, supports and reflectors.