A company called Airborne Snow Observatories Inc. has an image of Castle and Maroon Valleys from April 7, 2019 that is mesmerizing for anyone who loves to geek out on all things mountain related.

The company flew over the drainages toward the end of a very prolific winter for snowfall and just a few weeks after one of the biggest avalanches ever recorded in Colorado dumped tons of snow and debris into Conundrum Valley.

The image produced by the company, known by its acronym ASO, was captured by using sophisticated equipment and techniques to get a more complete picture of mountain snowpack. The image was color coded to show the deepest snow depth in red and the most shallow snowpack in blue. In the image, the Conundrum Valley floor is covered in red, representing snow depth greater than 5 meters. The avalanche path on the slope above through an area known as Five Fingers is black, representing a nearly complete lack of snow after the huge slide scoured the hillside down to the dirt.

In the background, the Maroon Bells and surrounding peaks are swathed in red, testimony to a very prolific winter of snowfall.

The same technology that was used to create the image will now be used on a broader scale through the Roaring Fork River basin to help water managers and local governmental entities get a more in-depth assessment of snowpack and the water volume to be expected during runoff. ASO touts its system as a giant step in information at a time when temperatures are warming, precipitation is variable and factors such as dust on snow make runoff unpredictable.

“Our mountain snowpack is our biggest reservoir by far and it turns out it’s pretty complicated as far as how much is where and when,” Jeff Deems, co-founder and chief technology officer for ASO, told the Pitkin County Commissioners in a meeting earlier this month.

Currently, water managers and snow geeks rely primarily on automated sites scattered around the mountains to measure snowpack. The U.S. Natural Resources Conservation Service has eight of the automated stations known as SnoTel sites in the Roaring Fork, Frying Pan and Crystal River valleys. The sites are valuable, Deems said, but limited in the information they offer. For example, many of the SnoTel sites are located in open meadows, which don’t reflect deeper snow depths accumulating in dark timber. Nearly all are at middle elevations, not reflecting snowpack above timberline or at lower elevations.

In addition, the snowpack is currently compared to the 30-year average, but Deems said that comparison makes little sense in a rapidly changing environment.

“Most of our water supply forecasting is based on the assumption that this year is like years in the past,” he said.

ASO has a technique that combines state-of-the-art remote sensing tools with snowpack modeling and fast-data processing to produce a more complete picture of snowpack conditions and runoff projections.

Around Aspen, ASO flew over the entire Roaring Fork watershed last summer to get baseline data on elevations. Sometime around April 1, when the water content contained in the snowpack typically reaches its peak, the company will fly the areas again, using laser scanners and a camera that measures the visible through infrared wavelengths. The technique measures the snow depth every 10 feet with an accuracy to 2 inches or better.

“We make a lot of passes. We basically mow the lawn, flying overlapping flight lines to get complete watershed coverage,” Deems said.

By combining these snow-depth measurements with a snow model to calculate snow density, ASO produces full-watershed inventories of snow-water equivalent in the snowpack.

The accurate and complete snowpack inventory supports improved runoff volume and timing forecasts, and helps water managers adapt to the rapid changes happening to snowpacks throughout the West.

“It’s this high resolution and full coverage that is the unique part of this,” Deems said. “We see a full inventory of the snowpack rather than just sampling a couple of points.”

The information will be available to the entities that are paying for the effort as well as the public at-large within three days of the flights, he said.

A second flight will be undertaken in the spring to get a second assessment after different factors — dust on snow, cold weather, precipitation or lack of it — affect runoff.

The areas that will be covered include the Fryingpan River above Ruedi Reservoir, the Roaring Fork River and Hunter Creek above Aspen, Castle and Maroon Creek, most of Woody Creek and Snowmass Creek above the village.

There is currently only one SnoTel site at the headwaters of the Roaring Fork River, on Lincoln Creek. There has never been snowpack data available on Castle and Maroon Creeks even though Aspen is dependent on them for water supply, so the effort will provide valuable data, Deems said.

AOS’s techniques were mastered over eight years as part of NASA’s Jet Propulsion Laboratory. The company went private in 2019 and operates in Colorado as a public benefit corporation. The company does extensive snowpack mapping in California and works with other entities for mapping snowpack in basins elsewhere in Colorado. The company has offices in Mammoth Lakes, California and in Glenwood Springs. This will be the first year it maps the Roaring Fork River basin snowpack.

Flying the area around Aspen and preparing the detailed report on the snowpack will cost an estimated $254,000. The contributors include the city of Aspen, $50,000; Pitkin County, $65,500 from its Healthy Rivers fund; the Colorado River District, $75,000; Snowmass Water and Sanitation District, $12,500; and Twin Lakes Canal Co., which operates diversions on the upper Roaring Fork River, $12,500.

There is a request to the participants in the Fryingpan-Arkansas Project, known as the Fry-Ark Project, for $50,000. In-kind service is being provided by the Colorado Basin River Forecast Center, U.S. Bureau of Reclamation and U.S. Geological Survey as well as the Ruedi Water and Power Authority.

April Long, executive director of the Ruedi Water and Power Authority, wrote a letter to Pitkin County urging support of the aerial-mapping project.

“With ongoing drought in the Roaring Fork Watershed and the need for each drop of water to meet several demands, understanding the amount of water available in our snowpack is more important than ever,” Long wrote.

She later added, “Airborne snow observations will provide a snow depth everywhere in the proposed basins, giving us the fullest picture we have ever had regarding the amount of snow that might yield water for the coming year.”

Deems said the snow-mapping flights are expected to be the state-of-the-art technology for the ­foreseeable future. While at the Jet Propulsion Laboratory, he and his colleagues explored uses of satellites to produce the mapping.

“In our best-case scenario, it’s going to be 30 years before we’re going to get a satellite in space to do what this does,” he said.