Jefferson County, CO Outdoor Lighting: Dark Sky Rules (2026)
Key Facts
- Full cut-off (mountains)
- All lamps / over 1,750 lumens
- Full cut-off (plains)
- Lamps over 2,800 lumens
- Pole height (mountains)
- 14 feet max
- Pole height (plains)
- 20 feet max
- Holiday lights
- Exempt, 60-day limit
Summary
Jeffco Section 12 requires exterior lights to be full cut-off fixtures above set brightness thresholds - all lamps in mountain areas, and lamps over roughly 1,750 lumens (residential) or 2,800 lumens (plains). Pole heights are capped at 14 feet in the mountains and 20 feet in the plains.
Pole heights in mountain areas shall not be greater than 14 feet. In the plains, a pole-mounted luminaire shall not be greater than 20 feet in height.
Full Breakdown
Section 12 of the Jefferson County Zoning Resolution governs outdoor lighting to minimize glare, light trespass, and misdirection of light. Section 12.E.1 requires that specified lamps be full cut-off fixtures: in mountain areas, all lamps in residential uses over about 1,750 lumens and all lamps in other uses; in the plains, all lamps over about 2,800 lumens. Certain accent lighting for entranceways, art, water features, and landscaping is exempt if concealed and narrowly focused. Section 12.E.3 caps pole heights at 14 feet in mountain areas and 20 feet in the plains. Holiday lights (60-day limit), FAA-required, emergency, street, construction, and vehicular lighting are exempt (Section 12.D).
Violations & Fines
New or substantially altered fixtures that are not full cut-off, or exceed pole-height limits, violate Section 12 under C.R.S. 30-28-124; the County may require corrective installation. Fixtures legally installed before Sept. 1, 2002 are grandfathered.
Frequently Asked Questions
Do dark-sky rules apply to my home's outdoor lights?
Are my existing lights grandfathered?
Sources & Official References
Other rules in Jefferson County
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