City okays dark sky ordinance

New rules effective immediately

In a 5-0 vote on Tuesday, Aug. 13, the Moab City Council approved rules that establish a lighting ordinance within city limits similar to the ordinance passed earlier this year by the Grand County Council.

The new rules require all new developments and most major redevelopments to comply with dark sky rules, which aim to reduce the amount of light pollution emitted from properties inside city limits. The rules also require all existing developments, residential and commercial alike, to come into compliance by August 2024.

Residents who replace “damaged or inoperative” lighting that is not already in compliance must use replacement fixtures that comply with the rules.

The new rules focus on four main components of outdoor lighting: color (also known as warmth or temperature), power (measured in lumens), shielding and timing.

The ordinance specifies limits on the color of outdoor lighting to a relatively red hue, rather than the relatively blue hue of daylight. Lighting manufacturers measure this in Kelvin, and 3,000 Kelvin is the new maximum for most outdoor fixtures.

Each property will have a minimum allowance for how much total light output is permitted from outdoor fixtures, and larger properties are provided a higher cap. For a half-acre property, the maximum is roughly equivalent to six 60-watt bulbs, and as outlined next, the lights must be well shielded.

Upglow (i.e. emitting light above the horizontal) is closely restricted, and light trespass (i.e. light that has direct spillage away from where it is considered useful) is also limited. The shape of the shielding around a light typically determines whether it is sufficiently shielded to prevent upglow and trespass.

Finally, the rules permit outdoor lighting at businesses until 10 p.m. or one hour after closing time, whichever is later. Businesses may use lights to illuminate entrances or parking lots at any time, to ensure safety.

The ordinance outlines special – sometimes stricter – rules for sign illumination, streetlights, parking lots, and certain other uses. See the final ordinance below for details.