Thornton, CO Outdoor Lighting: Dark Sky Rules (2026)
Key Facts
- Applies to
- Non-residential off-street parking in South Thornton URA
- Fixture type
- Indirect, diffused, or shielded fixtures required
- Max fixture height
- 35 feet
- Minimum intensity
- 1 foot-candle average, 0.4 minimum at any point
- Lighting hours
- One-half hour after sunset through hours of use
- Cross-reference
- Citywide standard at City Code Ch. 18, Art. VI, Div. 5
Summary
For non-residential off-street parking used after dark in the South Thornton Urban Renewal Authority area, City Code Section 10-260(d) requires shielded, indirect or diffused light fixtures no higher than 35 feet, aimed so light is not directed at residential uses, with minimum intensity of one foot-candle average and four-tenths foot-candle at any point.
(d)Off-street lighting. Off-street parking for non-residential uses that offers service after dark shall be lighted beginning one-half hour after sunset and continuing throughout the hours of use. If only a portion of the parking area is offered for use after dark, only that part shall be lighted. The lighting of the off-street parking area shall meet the following minimum requirements:(1)The intensity of light on the parking surface shall bea.An average of at least one foot-candle, initial measurement; andb.A minimum at any point of at least four-tenths foot-candle initial measurement.(2)The light source shall be indirect, diffused, or shielded type fixtures, installed to reduce glare and the consequent interference with boundary streets and adjacent property.(3)Fixtures shall be attached to buildings or mounted on poles in such a manner and at such a height that light is not directed at a residential use.(4)Maximum height of lights shall not exceed 35 feet.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 65).
Full Breakdown
Section 10-260 sits in Division 5, Light and Ventilation, of the South Thornton URA Non-Residential Property Maintenance Code, which under Section 10-236(b) applies only to existing non-residential structures and premises within the South Thornton URA area. Subsection (d) requires off-street parking for non-residential uses offering service after dark to be lit beginning one-half hour after sunset through the hours of use, and if only part of a lot is used after dark, only that portion must be lit. The lighting must meet a minimum intensity of an average of at least one foot-candle and a minimum of four-tenths foot-candle at any point on the parking surface, using indirect, diffused or shielded fixtures installed to cut glare and interference with boundary streets and adjacent property, mounted so light is not directed at a residential use, and capped at a maximum fixture height of 35 feet.
Subsection (e) points to the citywide zoning-based outdoor lighting standard in City Code Chapter 18, Article VI, Division 5 for requirements outside this maintenance code's non-residential South Thornton scope; that separate chapter was not part of the source reviewed for this record, so its provisions are not quoted here.
Violations & Fines
A parking lot lit with unshielded, non-diffused fixtures, fixtures exceeding 35 feet, or light aimed at a residential use fails Section 10-260(d) and is enforced through the code official's notice-and-order process under Section 10-242, with prosecution as a misdemeanor or civil infraction and each day of the violation counted separately under Section 10-241(c)-(d).
Frequently Asked Questions
Does South Thornton require shielded outdoor light fixtures for parking lots?
How tall can parking lot light poles be in this area?
Is this the citywide outdoor lighting rule for all of Thornton?
Sources & Official References
Other rules in Thornton
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