Feature December 19, 2018

Making it Snow

Sun Valley’s snowmaking team brings technology, hard work, and passion to work every night

Making snow for Sun Valley’s ski areas on Bald and Dollar mountains can be tough, cold, night-long work, but it doesn’t come without its perks. Sun Valley Snowmaking Manager Corey Allen figured that out his first night on the job 17 years ago this winter.

It was too warm to make snow, so he and the crew headed out from one of four snowmaking control buildings at a little over 7,200 feet to perform a routine check-up on the system.

“We went out to do some maintenance at about seven o’clock, and there were the Northern Lights,” Allen said. “I’d come all the way from Australia and had never experienced anything like that. So, we drove up to the top of Flying Squirrel and lay in the grass for about three hours and watched the magic of the Northern Lights unfold.”

Nearly two decades later, he’s one of four year-round people on the snowmaking crew that brings a combined 54 years of experience to the process of making man-made snow with one of America’s largest automated systems. In winter the crew expands to 15 or 16. Together, they guarantee a ski season every year no matter what Mother Nature throws at Central Idaho.

“It’s cold, it’s wet. Whether you’re on the towers or snowmakers at night dragging hoses, at times it can be miserable,” said Sun Valley Mountain Manager Peter Stearns. “But it’s so tangible. One, as a snowmaker, when you build 120 acres in three weeks and open the mountain and look up there and everything is brown and people are up there having fun—it’s incredibly rewarding.”

Allen said the snowmaking team is rightfully proud of the hard work they put in to guarantee Sun Valley’s skiing starts on time and stays top-notch through the whole season, but he also stressed that, for the right people, the magic of working on Bald Mountain at night or in the month of November when practically nobody else is up there is a different kind of payment and reward.

“The pride in building this thing and having this place to yourself at night are huge perks,” Allen said. “There are many experiences that many people in this town have never had, and we get them on a nightly basis: Northern Lights, shooting stars, sunrises, sunsets. In November and December things can be pretty hectic for us making snow, but as things start to slow down we try to encourage the guys to slow down and enjoy the ride a bit more. It’s okay to work your night around grabbing a coffee and going out and watching the sun rise.”

Snowmaking nozzle

The latest snowmaking nozzles are up to 10 times more efficient than the previous generation technology. Photo by Ray J. Gadd


Sun Valley is America’s original ski resort, but that doesn’t mean snow always arrives on cue. History bears that out. For the grand opening of the Sun Valley Lodge in December 1936 everything was in place except snow. Opening day, December 21, dawned on dusty ski runs and acres of brown sagebrush. Guests who had traveled to experience the magic of a white Christmas at the nation’s first ski resort were confused. Recognizing how important snow was to Sun Valley’s success, resort founder Averell Harriman promptly declared that guests stayed free until it snowed. On December 27, five inches fell. Another storm hit on New Year’s Eve, and Sun Valley skiing was born—if a few days later than planned.

It happened again in 1976-77 when it hardly snowed at all, and the resort’s new and underpowered snowmaking system couldn’t keep up. Local residents sported bumper stickers proclaiming: “I skied Squirrel and survived”—a testament to having navigated the thin, icy cover on one of Bald Mountain’s signature intermediate ski runs.

Such nail-biting experiences aren’t an option in today’s fast-paced resort climate. “The expectation has changed,” said Stearns, who’s been working at Sun Valley since 1980 and used to manage the snowmaking system. “When I first started in this business you skied what was there. That’s just not good enough anymore. Now you need to continually pursue perfection because people expect that.”

What Averell Harriman knew during Sun Valley’s 1936 grand opening when he gave guests free rooms is something that all local business owners know or will learn: There’s an intrinsic connection between snow and business in Sun Valley.

When the weather isn’t on Sun Valley’s side, the community collectively thanks the foresight of former resort owner, the late Earl Holding, who bought the place following the dismal winter of 1976-77. Holding and his wife, Carol, didn’t ski before buying the resort, but they soon found themselves on Bald Mountain with a ski instructor. The modest snowmaking on Lower Warm Springs and Flying Squirrel produced conditions more fit for ice skates than skis.

“Neither one of us knew what we were doing, but it wasn’t snow, and when we came back to the condo after that first day, Carol was black and blue from falling,” Holding recalled in a Skimagazine interview published Sept. 25, 2000. “I think (about) that first day or two and I saw the lack of any business and the frustration of people working here. I thought I should start with the snowmaking because it’s very difficult to run a business that is so weather dependent.”

Holding experimented with snowmaking equipment and combinations of air, water and temperatures in an attempt to produce man-made snow that was more powder and less ice. In its current configuration, when temperatures cooperate, snow guns can blanket 20 acres in a foot of snow in a day.

“Mr. Holding determined that if you were going to be in the A-game you needed to be able to deliver,” Stearns said. “It was great vision from his standpoint. That took place in 1990 when it really changed the way we do things here. I feel fortunate that we’ve been granted the tools to get us at least further along than most.”



There are four control buildings on Bald Mountain used to pump and regulate air and water through more than 38 miles of pipes and 120 miles of wires. Control Building One—or CB1 in mountain operations parlance—is the operations hub for the snowmaking system. It’s tucked in the trees near the bottom of Roundhouse Slope at about 7,235 feet.

CB1 has big bay doors and a cavernous garage where three large air compressors are positioned centrally. There’s another room nearby where six water pumps sit atop a 30,000-gallon tank of water. Between the two rooms is a small austere office with a computer console and three big monitors. Recently, Snowmaking Supervisor Jeremy Kaiser sat at the console and pulled up interactive simulated diagrams of the mountain’s snowmaking system. Its sophistication quickly became apparent.

He explained that there are four control buildings, nine air compressors, three 30,000-gallon water tanks, 18 water pumps, five cooling towers, seven submersible cooling pumps, 38 miles of steel pipes, more than 120 miles of computer and electricity wires, 110 weather stations and 578 automatic snow guns that can blanket 610 acres—about a third of the resort’s 2,100 acres of skiable terrain. With a click of his mouse, Kaiser toggled between the air and water systems. He was able to see
air pressure, water pressure, water temperature, whether valves were open or closed, what type of snow gun was mounted in a given location and what the temperature and humidity were anywhere on the mountain.

“Snowmaking itself is pretty simple,” Kaiser explained. “It’s just compressed air and pressurized water; that’s all we’re doing here. The pumps are pressurizing the water. The compressors are making compressed air and moving it to the hydrants at the guns. The hydrants regulate the amount of water or air that come out of the gun. All it’s doing, like your sprinkler at home, is spraying water from a nozzle that’s pressurized and broken up by air.”

The atomized water leaves the snow gun, and tiny crystals of snow begin to freeze on to nucleating agents—dust and other particles that happen to be in the air.

As the ambient temperature drops, the system’s efficiency improves. When it’s really cold, the mixture is about three-parts air to one-part water. On a warmer night—when the temperature is above approximately 22 Fahrenheit—the ratio might be more like 14-parts air to one-part water—far less efficient. “The warmer it gets, the more expensive the snow becomes,” Kaiser said. The reason for this is the compressed air, which, due to the electricity costs of pressurizing it, is the most expensive part of the equation.

The basic physics of the process are pretty simple, but, at the same time, the system and its management are complex. The relative humidity of the air, for example, is a critical variable: high humidity can make it very difficult to produce snow efficiently, even if it is cold out. Hang time is another important factor. Hang time is the time from when the water leaves the nozzle of the snow gun until it hits the ground. A long hang time gives the water droplets more time to freeze. This is why all of the new snow guns are tall aluminum tubes with nozzles 10-15 meters in the air. Other key variables the snowmakers take into account include snow quality, anticipated mountain traffic, time of day, and the aspect of a given slope, to name a few.

The logistics of installing and maintaining pipes, cables, weather stations and snow guns across the mountain is complicated, but the real genius of Sun Valley’s system is in its automation. Kaiser said it’s one of the most extensive automated systems in North America, matched only by its sister resort at Snowbasin, Utah, and a Virginia resort called Wintergreen. While there’s always a person at the controls, a computer handles the lion’s share of the work of actually making the snow and adjusting variables as weather dictates.

What that means, for example, is that Kaiser can turn snowmaking on for two neighboring ski runs and program the system to produce a certain amount and quality of snow. He can also prioritize one of the runs over the other. As resources allow, the system will adjust the air-water mixture and turn guns on or off to meet the predetermined goals, all while making sure the priority ski run is blanketed with the desired amount and quality of snow ahead of the second priority run.

“The slowest communicating guns talk with the system every four minutes, so, if the temperature is changing, the computer will adjust water every four minutes,” Allen said. “If it’s warming up through the day, the system will adjust every four minutes to take water away. You end up with the same quality snow; you’d just make less of it.”



Sun Valley started making snow with manual snow guns in 1974, and Holding vastly expanded the system in 1990, including the addition of computer automation. Improving and expanding the system is an evolution that continues today. Since 2014, with help from an Idaho Power Co. incentive program, Sun Valley has replaced 282 of its older snow guns with newer models that can cover more of the mountain at lower cost. Next summer, as part of a resort expansion in the Cold Springs drainage, it will add approximately 20 more guns to the system for a total of about 600 overall.

The cost savings of the new guns is achieved by using less compressed air, which, in turn, means using less electricity.

Allen held up one of each model as he explained. The older-model gun is shaped something like a gun and has two nozzles: one for air and one for water. Such guns use 180 to 280 cubic feet per minute of air. The new guns, which are shaped like cylinders, use only 17 or 18 cubic feet per minute of air.

The air of the entire system across the mountain, he explained, is essentially a giant reservoir. Pressure is supplied from CB1 at Roundhouse and CB3 at about 7,200 feet on the Warm Springs side of the mountain and is a constant 110 pounds per square inch. Put another way: The resort can make 20 gallons of snow per minute with one of the older guns. With the same amount of power, it can turn on 10 of the new guns and create 200 gallons per minute.

“Both guns use a similar amount of water at the same temperature,” Allen said. “If you turn off the older model, you all of a sudden can turn on 10 more guns over a whole ski run where before you only operated one gun. The name of the game, given the expense we incur doing this, is: we’re looking to get it turned on and get it turned off. The new guns will help us get there faster and with less water.

“If we have a historically average November and December temperature pattern, we’re 95 percent done by Christmas. We come back after Christmas and fatten things up for five to seven days, and we’re done.”



It’s easy to imagine snowmaking as a cold, dark and difficult job—and it’s not without its challenges—but Allen downplayed the rigors.

“We actually have one of the best snowmaking climates in the world,” he said. “We definitely have our moments here, but when we have them it’s what other ski areas go through three times in a week. We have our battles, but to be honest it’s not too bad.”

One of the most problematic scenarios is when one of the pipes begins to leak in winter. The only solution is to drag an excavator up the mountain behind a snowcat, dig a big hole, crawl into the hole and wrench on a frozen, high-pressure water pipe in the middle of winter. “That’s something we prepare for every year by testing all of our lines, but it’s something that just happens sometimes,” Allen said.

While the work of actually making snow is the most visible and fun part of the job, Allen and Kaiser agreed that most of the work actually happens during fair-weather seasons when the skiing public isn’t watching at all.

“Wintertime’s the fun part, but we make 95 percent of our snow in the summer,” he said. “Our thing is safety and efficiency. We definitely focus on the system’s weaknesses in the summer so that we’re not as exposed in the winter.”

In addition to pressure testing water and air lines, another of the common off-season maintenance projects is to repair the system’s wires, which can be damaged by something as simple as a rodent. “You really only need a mouse to chew on and expose a half inch of something, or even less, and now you can’t talk to 200 snow guns,” Allen said. “That’s the kind of thing we’re repairing all summer long. We’ve found a weakness in our communication wires right now [mid-October], so we’re preparing to pull dialogue cable from top to bottom on Christmas Ridge next week.”

That means pulling 2,700 linear feet of wire weighing more than 50 pounds through a conduit over about 1,000 vertical feet, a job they said would take six people on the team two or three hours.

“There’s a lot to get your head around, and even the sharpest mind could come in here for a season and still only have a fraction of the knowledge,” Allen said. “Local knowledge is huge. Experienced snowmakers can come in here and operate this thing, but if something goes wrong they’re going to fall in a heap. Local knowledge is huge.”



Snowmaking Manager Dennis Harper has been working in snowmaking at Sun Valley since 1998. He called the job “a lot of manual labor, but intellectual and problem solving—kind of an art with a little bit of luck.” Still, he stressed that Sun Valley’s success ultimately boils down to having a strong team. “These are some great guys who understand the vision,” Harper said.

For their parts, Allen and Kaiser agreed that being part of a strong, committed team is integral to making it all work. But at the end of the day, they also said that a lot of their passion comes from their love of skiing and snowboarding. “Those things we talked about: riding the ski lift, watching the sun go down, seeing the Northern Lights, blasting a six-foot pile of snow—that’s all part of the fun of it, but in the end it’s about making the mountain skiable so you can ride it,” Kaiser said.

Allen put it this way: “Snowboarding is the best part of the job. My motto has always been, ‘be cool is the rule.’ So let’s do this, make it safe and make it skiable. That’s my passion. We’re here to ride, too.”

This article appears in the Issue of Sun Valley Magazine.