Snowpack peaks, shifting view toward runoff
A blustery winter in the Roaring Fork watershed could mean a long, steady snowmelt for the rivers. But Mother Nature could still influence how the above-average snowpack flows into the waterways.
“The next two weeks or so really dictate how quickly that snowpack starts to melt,” said Erin Walter, service hydrologist with the National Weather Service.
This season, snowpack peaked on April 7 with 23.2 inches of snow-water equivalent, about five inches above average, according to the USDA.
Consistent snowfall throughout the season contributed to the 35% above-average count – the highest snowpack for the second week of April since 2019.
Experts said it is still too soon to tell exactly what the snowmelt pattern will look like. Factors like temperature, wind, and dust will play into that rate.
If temperatures continue to rise and wind storms blow away top layers of snow or carry in dirt — the most detrimental to snowpack — rivers could swell and lead to strong flow or even flooding.
Or if cold weather like Friday continues, the snowmelt could come at a more even pace all the way into July. Normal peak runoff season in the Roaring Fork watershed is mid-May through mid-June.
Walter said elevation also plays a huge role in the rate of snowmelt. The highest elevations hold out the longest.
“For upper level basins, we haven’t (had snowmelt) yet, but we did see that more so in our lower level snowpack, like up to about 9,500 feet and then there’s a mid level 9,500 to 11,000 that has started to trend downward in the Roaring Fork area due to those warmer temperatures,” she said.
Another factor in extending the runoff season is better soil moisture at the beginning of winter than in seasons past.
“This winter, we’re heading in with better soil moisture. And so the hope is that then that water finds its way into the river rather than into the ground,” said Roaring Fork Conservancy water quality technician Matthew Anderson.
The appeal of a drawn-out runoff is to keep the rivers at higher levels longer into the summer with cold water from high elevation. And it abates flood risk with a slow, steady melt.
Experts agreed this season’s snowpack level is heartening as the Western Slope faces greater demand for water in an era of drought. Still, Walter cautioned that the problem is greater than one good season.
“One good point to make is that a good year does not solve most large-scale problems,” she said. “It’s going to help us this year, but that doesn’t resolve the issue that there are a lot of high demands, and people that depend on the Upper Colorado River Basin.”
While more moisture in the soil is good from a wildfire prevention perspective, she also pointed out that all the moisture encouraged growth in the forest that could catch fire easier later in the summer.
“The one thing that would cause an issue is with as much moisture as we’ve had, we’ve seen a lot of green up; so you have some of those finer fuels that have been able to grow back,” she said. “If we start to see a dry period, then those would be the first to dry out of here, and that would be problematic for a dry and windy day or red-flag conditions.”
And from a public-safety standpoint, above-average snowpack likely means greater flood risk.
Valerie MacDonald is the emergency manager with Pitkin County. She said that her office is preparing for worst-case scenario as a precaution.
“Worst-case scenario, and I don’t mean to be an alarmist, but things we think about are debris flows,” she said. “Debris flows can happen in a high-water year when we’re in this freeze-melt cycle. Maybe it’ll all be fine, but we’re preparing for the worst, which is our job.”
She said the county has a variety of public safety teams ready to activate to protect people and infrastructure.
Signing up for Pitkin Alerts is the best way to stay informed, she said, about high water and flooding in the area, with real-time instructions on how to stay safe. And the ReachWell phone app offers translation services for all Pitkin Alerts.