Snowpack news: Yampa and White watersheds dip below 2002

From the Craig Daily Press (Tom Ross):

The Yampa River was clearly swollen and discolored Wednesday where it flows through downtown Steamboat Springs, and after Tuesday’s temperatures reached into the 60s, that won’t come as a surprise to valley residents.

It’s impossible to avoid noticing how rapidly snow is melting from roof tops and south-facing embankments. Aspen trees are in the earliest stages of budding in some places, and green shoots from flower bulbs are emerging weeks ahead of schedule.

The Yampa’s flows of 337 cubic feet per second Wednesday, where it passes beneath the Fifth Street Bridge in Steamboat, were more than double the median for the date, according to records kept by the U.S. Geological Survey.

In a winter of sub-par snowfall across Colorado, the west summit of Rabbit Ears Pass has been an isolated location with near-normal snowpack (water stored in the standing snow), according to monitoring by the National Resources Conservation Service.

However, there, at about 9,300 feet, the trend has reverted to unseasonably warm and dry conditions since March began with three days of welcome snowfall.

The NRCS recorded that the snowpack on Rabbit Ears March 4 stood at 94 percent of median for the date. But that number has dropped off steadily since then, losing 12 points – the equivalent of four-10ths of an inch of stored water – down to 82 percent of median for March 18. The median snowpack for March 18 is 22.2 inches and growing…

The Yampa is a tributary of the Green River where it leaves the northwestern corner of Moffat County, ultimately flowing into the Colorado in Canyonlands National Park in Utah.

Just below Craig, where the Yampa has picked up flows from the Elk River, Trout Creek, Elkhead Creek and other tributaries, the river was flowing at 1,040 cfs at midday Wednesday, compared to the median of 638 cfs.

The Elk was also flowing above the median Wednesday — 312 cfs compared to the median for the date of 152 cfs.

The Elk River Snotel, where the RCS monitors snowpack on the western edge of the Mount Zirkel Wilderness in North Routt, is currently at 69 percent of median.

From The Grand Junction Daily Sentinel (Dennis Webb):

“Other duties as assigned” may be
 a typical part of Americans’ job descriptions, but one of Derrick Wyle’s other duties is far from typical.

His official job is serving as a soil conservationist with the U.S. Department of Agriculture’s Natural Resources Conservation Service, assisting agricultural operators in the region out of the agency’s Glenwood Springs office. But on two days a month during the winter, he turns his attention to snow rather than soil, heading out on snowshoes to measure snowpack at a couple of area locations.

“This is collateral duty. Oh shucks, right? Two days out of every month, you have to go out and play in the snow,” Wyle said during a recent demonstration of the work on McClure Pass south of Carbondale. It was part of an educational program put on by the Roaring Fork Conservancy nonprofit group, which advocates and educates on behalf of the Roaring Fork River watershed.

While it beats a day in the office, Wyle’s snow survey duties are clearly far more work than play. As observers learned during Wyle’s presentation, the measurement process itself is fairly exacting. And then there are challenges — like Wyle once having had to dig out a buried gate during a snowmobile ride to one site, and the ever-present prospect of an emergency occurring that could require an unplanned night outdoors.

Wyle and other surveyors must undergo training including building a snow cave in case of such an event, and this soil conservationist who came to Colorado from snow-free Florida has spent the night in one, but as part of the training, not an emergency, thank goodness.

WHY IT MATTERS

The survey work Wyle and others do in Colorado and other states is part of a tradition dating back many generations, and it’s something that looks likely to continue for decades to come, even as automation is increasingly used to measure snowpack levels instead. As it turns out, a number of approaches to getting the job done exist, all with their pluses and minuses, but with the most important thing being that snowpack is accurately measured because of its importance to states like Colorado.

From skiing to rafting and other river-related recreation, to preserving fish and plant habitat and rivers as living ecosystems, “it’s all connected back to snow,” said Sarah Johnson, education and outreach coordinator for the Roaring Fork Conservancy.

Snowpack likewise has implications for agricultural, industrial and municipal water availability and use.

“The mountain snowpack is the West’s largest reservoir, and the only way we know what’s in our reservoirs, that snowpack, are these … measurements that are taken and recorded,” said Chris Treese, external affairs manager with the Colorado River Water Conservation District, based in Glenwood Springs.

Conservation service snowpack data helps in predicting winter avalanche danger and forecasting the year’s spring runoff and streamflows. It assists water managers in managing reservoir and river levels for purposes ranging from fulfilling water rights obligations and providing hydroelectric power to avoiding floods and helping endangered fish.

DOING THE FIELD WORK

Snowpack measurement has a storied history, in Colorado dating at least as far back as Enos Mills in the early 20th century. Besides leading the push for the creation of Rocky Mountain National Park, he once engaged in work as a snow observer, a job that let him spend lots of time in the backcountry he so loved.

That work is carried on in a more systematic manner today by snow surveyors like Wyle, through monthly trips to established snow course sites. Those sites are marked by signs, and surveyors walk a transect along the course, taking measurements at prescribed intervals.

“We try to hit the same point every time we go out there,” Wyle said. Consistency in measurement locations adds to the comparative value of the data being measured over time.

Surveyors work in teams of two, using up to four tubes to sample the snow. The tubes are 30 inches long each, and are screwed together to a length exceeding the snow depth.

“It’s a big (snow) year that we actually get to use all four,” Wyle said.

Surveyors are careful not to touch the metal tubes with bare hands, as that warms them up and can cause snow to stick to the inside. Tossing the tubes into the snow is a good means of cooling them off if they’re too warm.

The business end of the assembled tube has a drill-bit-like end on it. At each measurement point, a surveyor plunges the tube straight into the snow until hitting the ground, then turns the bit slightly in an attempt get a small plug of dirt to ensure the ground has been reached. If there’s no plug when the tube is removed, another sample must be taken.

With the tube still in the snow, the surveyor looks at a scale on it to read the snow depth. It’s then removed, and after digging out the dirt plug the surveyors use a spring scale to weigh the tube with the snow sample inside. The scale reads in inches of water, and after getting an initial reading, surveyors subtract the empty weight of the tube to determine the snow water equivalent.

They then can divide that number by the depth to determine the snow’s density in a percentage form. That density might be a small percentage when falling as powder in cold temperatures, and increase as the snow settles, is packed by wind, or melts and turns back into crystals.

Samples along the snow course should be within about 5 percent of each other in terms of their density, which wouldn’t normally vary greatly in the same area. If there’s a bigger difference, the surveyors know they’re doing something wrong with their measurements and need to check their work.

Slots in the tubes also let surveyors check the core inside. It’s typically not as long as the measured depth, because the snow compacts as the tube is pushed to the ground. But the core should be no less than half the length of measured depth, or surveyors will suspect a problem such as a void in the snowpack, and will measure again.

Once a measurement is completed, a surveyor can tap the tube on a snowshoe to dislodge the core (being careful not to tap with that sharp, drill-bit end), look through the tube to make sure it’s clear (but again, being careful not to do so with the business end against their eyes), pace off to the next transect point and repeat.

“Who knew this could be so …,” Carol DePaul of Carbondale, a participant in the recent tour, said after giving it a try. She didn’t complete her thought, but could have finished it with words like “precise” or “involved.” Wyle gently corrected people as they grabbed tubes barehanded, failed to get a dirt core, forgot to measure depth before removing the tube from the snow, and the list went on. There were enough opportunities to mess up during enough different steps in the process that, for fear of embarrassment this reporter rejected Wyle’s repeated offers to give it a try.

“If I was snow surveying with you I’d make you do it again because you didn’t get any soil,” Wyle teased a braver party who had just pulled the tube from the snow.

HIGHER-TECH MEANS

Still, the process isn’t rocket science, and it probably becomes second nature after enough repetition, which there’s plenty of on this job.

But not far from where Wyle was giving his demonstration on McClure Pass sits on automated snowpack measurement site that incorporates, if not rocket science, at least a little bit of space technology in its operation. It’s known as a SNOTEL, or snow telemetry, site, something that has become the mainstay of the conservation service’s snow survey program.

Key to such solar-powered sites is a pillow-like device that sits on the ground and contains antifreeze. As snow falls on it, the weight pushes some of the antifreeze out of the pillow and it rises up a measurement tube in a cylindrical room nearby. The measurement can then be transmitted by a signal that’s sent high into the sky, bounces off orbiting meteor debris and returns to Earth at a centralized data collection center.

A tower over the pillow also has a small sensor arm reaching out horizontally that can measure the depth of the snow above the pillow by ultrasonic means, based on how long it takes a signal to reach the snow and return to the sensor.

Other gauges at SNOTEL sites also take rain and temperature readings. All the readings are accessed hourly.

Yet other means have been employed to measure snow. At some locations, airplanes fly over sites containing posts of different heights. Snow depth can be determined by how many posts are visible. Density and snow water equivalent can be inferred based on readings in similar but physically accessible nearby areas.

One such site used to exist at McClure Pass, as did a manual snow course, but now the conservation service has only a SNOTEL site there.

Wyle said he thinks aerial sites tend to be found these days in places like California and the Pacific Northwest, where snow measurements may be wanted in remote, deep locations. Such coastal locations also may have 20 feet of snow, and a less-precise measurement may be less important.

A far more modern, aerial-based approach to snowpack measurement makes use of LIDAR, or Light Detection and Ranging, which is like radar, but uses a laser rather than sound. Terrain can be measured by flying overhead, then again in winter to measure the difference with snow on the ground, using highly accurate mapping.

“This is the future of snow science, snow surveys,” said Johnson, of the Roaring Fork Conservancy, noting how far things have come from the days of Enos Mills.

But that future still may be a ways off. Brian Domonkos, the conservation service’s Colorado snow survey and water forecasting supervisor, said LIDAR isn’t used at all by the service in Colorado. Wyle said it can be hazardous and expensive to have to fly all over.

“I don’t think this is going to catch on until we can do satellite-based LIDAR,” Wyle predicted.

From the Fort Collins Coloradoan (Sarah Jane Kyle):

Northern Colorado’s river basin is nearly at normal snowpack levels for the year, but still below last year’s snowpack.

The South Platte River Basin is at 96 percent of the median but only at 67 percent of 2014, which was 143 percent above normal, according to data from NRCS SNOTEL sites, which measure snowpack instantaneously.

The Cache la Poudre Basin, which is part of the South Platte River Basin and controls much of Fort Collins’ water supply, was at 103 percent above normal snowpack during a formal March 1 measurement. The same time last year, the basin was at 147 percent of normal.

During the same measurement, the South Platte was at 110 percent of normal. The same time last year, it was at 151 percent of normal.

Heavy snows in February pushed both basins — and Fort Collins proper — above average. Last month was the snowiest February in Fort Collins since the 1920s with 17 inches of snowfall, or 10.1 inches above normal, at the CSU weather station in February.

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