Aspen goes dark with a new ordinance that punishes “light trespass”

They sounded a little like the rules for a summer camp in the mountains, but they were written for Colorado’s wealthiest ski town. 

The city of Aspen implemented a new ordinance in December that asks residents and businesses to turn off indoor and outdoor lights if light from their buildings pours a certain point beyond their property line or face a fine for “light trespass.” 

Along with the new outdoor lighting code came a curfew: lights out on homes and businesses from 10 p.m. to 7 a.m., or an hour past closing or before opening for businesses that operate outside of those hours. 

The edict continues: To curb light during curfew hours, property owners “may need to close window shades, turn off, or dim lights.” All outdoor lighting on private property and any light fixtures replaced after Dec. 14 must also adhere to the regulations. If residents let their measurable light “extend beyond the intended usage area,” anyone can file a complaint through Aspen 311 Connect, an online platform for community members to request service from the city — and call out neighbors or business owners, with a possible court summons on the table.  

If rules dictating how much light a person can shine on their property sounds extreme, the number of Colorado cities and towns embracing them suggests they’re wanted. 

For years, cities up and down the Front Range have enforced, or tried to enforce, night-time light ordinances. 

Boulder’s rules, implemented in 2018, target homeowners in residential zones and prohibit “any upward oriented lighting,” “any lamp or bulb, except for seasonal displays and landscape ornamental lighting, visible beyond the property line,” and “any lamp or bulb with a correlated color temperature that exceeds 3,000 degrees Kelvin.” (Think of the Kelvin measurement here in terms of feng shui for lighting: 2,700K is “soft white, friendly and comfortable,” 3,000K is “warm white, pleasing and clean,” and 5,000K is “cool white, bright and crisp,” according to e-conolight, a distributor of LED lighting.)

Fort Collins adopted new exterior lighting standards in a land use code that took effect in 2021 and covers new commercial and multifamily residential projects. The purpose was to ensure adequate exterior lighting “for the safety, security, enjoyment and function of the proposed land use,” while also conserving energy and resources, reducing light trespass, glare, artificial night glow and obtrusive light, and protecting the local natural ecosystem from damaging effects of artificial lighting. 

Windsor and Arapaho County also have light trespass requirements, said Brittany Lynch a senior designer at Clanton & Associates, which does lighting design and engineering across the state. “The Model Lighting Ordinance that will be released this year will also include light trespass requirements,” she said.

A growing number of small towns are implementing or revising their lighting ordinances, as well, including Breckenridge, Gypsum, Winter Park and Avon. Some are doing it to preserve part of what made the towns special in the first place — darkness unadulterated by artificial light and all of the wonder that comes with it — while others are taking first steps toward Colorado DarkSky designation. 

The wealthy and indoor light

It turns out America’s wealthiest people love to leave their windows uncovered.

Those who earn more than $150,000 are almost twice as likely to do so as those making $20,000 to $29,000, according to a large 2013 study for the U.S. Department of Energy that has gotten a lot of attention in recent days.

Dutch people are said to opt out of window dressings, too, possibly because their religious tradition of Calvinism insists honest citizens have nothing to hide. 

Aspen has no dominant religion, but it does have a bunch of millionaires and billionaires. They often live in mansions that can cost $8,000 per square foot. A quick look at pictures of homes on Aspen’s tony Red Mountain — the $38,500,000 six-bed, seven-bath manse on Hunter Creek Road, say, or the $20,750,000 four-bed, five-bath place on Draw Drive — show giant planes of glass buck naked to the sky. 

A lot of Aspenites like to let their indoor light pour out of their uncovered windows, said Haley Hart, the city’s long-range planner for community development. That can pile up, given the size of some of the houses. But city leaders want all residents to take stock of their personal light pollution. 

Aspen isn’t the only Colorado town where light ordinances are put in place to curtail light coming from inside a person’s home, Hart added. But Lynch said it is the only community she knows of with a light curfew. 

“We have a whole system of enforcement because we have so many lighting concerns and complaints,” Hart said. “A lot of them are more about there’s lights on in our yard or light pouring into the Roaring Fork River, or about holiday lighting obscuring people’s views of the mountains.” The latter is one reason the city limited “seasonal lighting, formerly known as holiday lighting” to between Nov. 15 and March 1.

“Aspen is a resort community and people love coming here and having the holiday lights, like on our 60-foot-tall Sardy House Christmas tree,” Hart said, “so our idea with the updated code was to create some guardrails. We don’t want people’s seasonal lights shining in their neighbors’ windows. But enforcement is entirely complaint-based. We’re not walking around with meters. If someone’s lights are egregious at 2 a.m., then a formal complaint can start the enforcement process.” 

“Light trespass is a newer concept, but I think it will help us enforce rules upon these homes lit up year-round — with lots of glass, where everyone can see inside. We’re not saying turn your lights off completely, but after curfew you need to dim them or draw your blinds,” she said. 

Light ordinances benefit flora, fauna, fish and people 

As heavy-handed as all of this may sound, it could be beneficial for Aspen. 

It’s the first time the city’s lighting code has been updated since 2003, and the previous version code “had no consideration of LED lighting,” Hart said. Nor did it consider “performance or quality of light generated on a property. Parcels in town and parcels in our more rural areas were being judged on the same level. And a lot of longtime locals have concerns about lighting being directed into stream margins in the Roaring Fork, Maroon Creek and Castle Creek. A lot of tributaries and creeks are within our communities, and recent research shows direct light into streams can damage aquatic life.” 

Kyle Horton, a professor of fish, wildlife and conservation biology at Colorado State University, said artificial light shining into rivers at night can negatively impact invertebrates and fish by reducing nighttime drift of larval aquatic insects because of the disruption to their circadian rhythms, which can lead to diminished reproduction and less food for fish. 

Artificial light in urban areas impacts insects both directly and indirectly, according to a 308-page study of Colorado native pollinating insects in 2022 and 2023.

Moths attracted to outdoor lights can die from over-expenditure of energy used to flit around them. And on sites in Denver with pole lights, cheatgrass grows five times higher than sites with no pole lights, leading to crowding out of native flower communities and a 49% reduction in body mass of larva that grow into rustic shoulder-knot moths, a key Colorado pollinator species.  

Nocturnal light is also one of the key drivers of changes in bird migration stopover, when birds rest, refuel, and seek shelter during their bi-annual migration, the most perilous stage of their lifecycle. Horton said it’s during stopovers when birds collide with structures and die by cat predation. To help migrating birds, he and CSU’s Aeroeco Lab post “lights out” alerts to notify building managers and residents with the ability to turn off their lights when a night migration is coming. And Lights Out Colorado, The National Audubon Society, the International Dark-Sky Association and Denver Audubon have encouraged people to shut off, shield or alter their lighting in April, May, August and September, to help save millions of migrating birds flying over Colorado.  

“On the human side, studies have shown chronic exposure to light can lead to stress, heart disease and risk of various types of cancer,” Horton added. 

Way back in 2001, two-thirds of the U.S. population and more than one-half of the European population had already lost the ability to see the Milky Way with the naked eye, according to “The First World Atlas of the Artificial Night Sky Brightness,” a report on global light pollution published in the Monthly Notices of the Royal Astronomical Society.

An estimated 63% of the world population and 99% of the population of the European Union and the United States (excluding Alaska and Hawaii) lived in areas where the night sky was brighter than the threshold for light-polluted status set by the International Astronomical Union, meaning the artificial sky brightness was greater than 10% of the natural sky brightness above 45 degrees of elevation, the report says. 

Related studies showed prolonged exposure to artificial light prevents many trees from adjusting to seasonal variations; research on insects, turtles, birds, fish, reptiles and other wildlife species revealed light pollution can alter behaviors, foraging areas and breeding cycles; and in humans, a compelling amount of epidemiologic evidence pointed to a consistent association between exposure to indoor artificial nighttime light and health problems such as breast cancer.

So it’s likely good that more and more towns are lining up to have the Colorado Tourism Office help them learn about and apply for Colorado DarkSky designation. 

Aspen’s new code “is heavily based on the DarkSky model ordinance,” Hart said, but the city isn’t going for designation at the moment. 

If ever does decide to, it can take cues from Durango’s playbook. 

Last year, the city of 20,000 decided to seek DarkSky Community designation. If awarded, Durango will be the largest city in Colorado to get it, said Hayes Norris of the Colorado Tourism Office. In 2023, six other Colorado locations — Bayfield, Grand Lake, Rangely, Silverton, Visit Estes Park and the Western Slope Dark Sky Association — were approved to participate in the Colorado Tourism Office’s Dark Sky Mentor Program, joining the City of Durango, Friends of Browns Canyon, Ridgway State Park and Sangre de Cristo Dark Sky Reserve. 

Hart said Aspen’s light curfew came on line Dec. 15, 2023, and that “we’ve had positive feedback — we’ve been working on it for two years with lots of public engagement. We also sent out drafts at 50%, 75% and 90% completed. By the time we got to 100% we had a really solid document that we felt good about, and the city council passed it 5-0 ,which we were really excited about.”  

“I think Aspen in general is a pretty regulated place, a small community with high stakes,” she added, “so it might be more common within Aspen to have a document that’s taking a more scrutinizing approach to how people are interacting with the environment.” 

As for feelings Aspen residents have about their new regulations?

“I haven’t heard of them,” said Greg McFadden, who lives right downtown and prefers dark sky to artificial light.

Type of Story: News

Based on facts, either observed and verified directly by the reporter, or reported and verified from knowledgeable sources.