Eric Saltmarsh
The central portion of the Milky Way, rising before dawn in March 2022, as seen from Eldorado.
The City of Santa Fe’s recent streetlight conversion project left some stargazers and night-drivers with more knowledge about kelvins and kilowatt hours than a layman might want to have. It brought up considerations of safety, energy efficiency and how best to preserve a dark night sky.
Last October, city officials began installing LED luminaires in streetlights. The $2.9 million project was part of the city’s effort to go carbon-neutral by 2040, with the added benefit of saving $556,000 annually in electricity bills, and 2 million kilowatt hours of energy per year (an electric dishwasher uses roughly 2 kilowatt hours per load). The city owns about 3,000 of the 5,000 streetlights in town; Public Service Company of New Mexico owns the rest, which have yet to be converted.
Mayor Alan Webber and other city officials also touted the project as reducing light pollution—but not everyone agreed.
The Santa Fe Conservation Trust, a nonprofit working to protect culturally and environmentally significant landscapes, was concerned that the new lights would be too far on the blue spectrum, “which creates more light pollution and has more impact on all living beings,” says executive director Sarah Noss. The group lauded the city for its efforts to save energy, but advocated for the new LEDs to be more amber in hue.
The new streetlights are “the warmest and dimmest design you could do,” within certain parameters, city Public Works Division Director Regina Wheeler tells SFR, citing a 10-year warranty, a tier-one manufacturer and lights that meet national safety standards.
Members of the Conservation Trust believe the switch has increased sky glow, but they don’t know for sure because there’s no baseline against which to compare the new lights. Now, they’re looking to change that by installing light-monitoring equipment on Santa Fe County buildings, including fire stations, which would collect light pollution data every five minutes throughout the night.
Retired astrophysicist Sam Finn introduced the group to the monitoring equipment, and the trust will be part of part of a long-term light pollution study with the Flagstaff Dark Skies Coalition.
The work will help “keep an eye on the light pollution,” Noss says. “If we had that kind of information in our quiver, we could more forcefully understand if we needed to improve our laws protecting the night skies.”
Finn says the only data available now are from weather satellites, “but that data is crude and you have to make a number of assumptions in order to use it to make statements about changes in the light level,” he adds.
The trust is working with Santa Fe County Commissioner Hank Hughes to finalize the equipment’s placement. Hughes supports the project.
“I’ve lived here 30-plus years, and we’ve already seen the sky get brighter from the lights in Santa Fe,” Hughes tells SFR. “There’s already some degradation, so that’s why I think it’s important not to let it get any worse and hopefully, maybe even make it a little bit better.”
Noss says the group plans to gather 10 years’ worth of data with three monitoring stations—one to the north of the city, one to the south and one to the southeast—to track light pollution in northern Santa Fe County, including within city limits.
“We needed to put them far enough outside the city so that we could really assess the light dome,” Noss says, “and we also needed to put them in areas where the ambient light—street lights and traffic lights and things like that—weren’t gonna really impact the data.”
The trust will download the data every couple weeks, and both analyze it locally and send it to the group in Flagstaff for analysis.
“It’s kind of a big deal, but it’s something that we feel like we can do and that we’re committed to because we really want to protect the night sky as much as we can,” Noss says.
Charitable contributions to the Conservation Trust will fund the project. Noss estimates the startup cost at $7,000, with an annual cost of roughly $1,000 for data downloads and equipment maintenance.
The dark sky protections on the books “don’t really have teeth,” Noss says. “Our hope is that if we can show that things are changing fairly quickly in terms of our ability to see the night sky, it would help us strengthen the statutes that are already in existence.”
Santa Fe’s light pollution ordinances haven’t been updated since 2011, though the city did pass specifications for smart street lighting design in 2021 which will be be incorporated into the code when it’s updated.
Wheeler, too, would like to see more stringent ordinances, though she believes the city streetlight conversion has improved light pollution.
“Through this whole streetlight process, we realized that we would really like to be a dark-sky community,” she says. “One of the phases of that would be really starting to talk to the private sector about how they can do better, and then making our ordinances stricter.”
The city is rewriting the land use code, which Wheeler calls a “golden opportunity” for this type of work. But because the jobs of Engineering Division director, engineering supervisors and other staff are vacant, she says it’ll be a slow process.
The city’s next step is converting the PNM-owned lights.
“Because some of the specifications we came up with were so progressive about our lighting design, [PNM] actually had to go get [Public Regulation Commission] approval to install this kind of equipment,” Wheeler says.
She expects to see a quote from PNM within the next couple months.
“My guess would be, we’ll probably be in business with a new conversion in January,” Wheeler says.
For the Conservation Trust, the stakes are high.
“To me, what’s important about preserving night skies is that it’s a natural resource that has been there forever,” Noss says. “If we can preserve the night sky, we look at the same stars that our ancestors looked at and revered and built their lives around.”
Further, lighting impacts melatonin levels in humans, she says: The lighter the night sky, the worse sleep quality will be. And those are just the human impacts—she says it affects animals’ mating patterns, how blooming plants open at night, feeding insects and more.
The good news, she says, is that dark skies are “totally recoverable” by reducing certain kinds of lighting (like light that bounces off sidewalks from streetlights).
“It’s not the hardest thing in the world to do if everybody’s aware of the reasons to do it,” Noss says.
