Melting snow usually means water for the West. But this year, it might not be enough
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There's still snow in Colorado's mountains near the headwaters of the South Platte River, and Brian Domonkos has strapped on a pair of cross-country skis to come measure it.
He's the Colorado Snow Survey supervisor, and knowing how much snowpack is left from the winter to run off into streams, rivers and reservoirs this summer is crucial, especially in a year when much of the West is in extreme drought. As it melts, the snowpack here will become the primary source of water for millions of people in Colorado and across the western U.S.
Domonkos skis to specific points on what's called a snow course. He jabs a tall metal pipe into the snow to collect a core sample, then weighs it to calculate how much moisture it holds.
The snowpack at the South Platte's headwaters is above 110 percent of normal levels for this time of year, but that's not the case for the rest of the state. In southwest Colorado, it's less than 40 percent in areas that are already experiencing a historic drought.
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The trend is concerning, Domonkos says, and part of how the warming climate is disrupting this delicate system in multiple ways.
"That might be the real wow factor for me, where these soil moisture deficits and low stream flows that we're seeing in the fall prior are having such a massive impact on the current year streams," he says.
Year after year, unusually dry soils from warmer than normal temperatures and a lack of moisture are absorbing a lot of the water that melts from the snowpack. This means that water isn't making it into rivers and streams, essentially limiting the efficiency of the melting snow.
Even a year with an above-normal snowpack might not push Colorado out of a shorter-term drought, Domonkos says. Plus, warmer temperatures also mean less snowpack accumulation.
"That's where I think some of our concerns, for us as professionals that do this, the deeper we get we wonder if we're able to get out of it," he says.
Colorado has also been missing out on its late summer monsoon rains the last few years. Assistant state climatologist Becky Bolinger says that means the soils don't have a chance to catch up on moisture until the snow melts.
"Your soils are dry, which gets into this unfortunate feedback loop of hot soils, evaporating dry and hot air," she says
Last year was a good example — no big monsoon showed up in 2020, and "incredibly hot temperatures" dried out the soil.
In years that start with a water deficit, like this one, melting snowpack saturates the soil first.
"In order to have a normal runoff season and get what you need into the reservoirs, you need above-average snowpack," Bolinger says.
Poor snowpack efficiency doesn't just impact Colorado. Reservoirs Lake Powell and Lake Mead are projected to shrink to historic lows in the coming months, which could trigger the federal government's first-ever official shortage declaration. That would mean mandatory water cutbacks in some states.
The Colorado River, which starts in the Rocky Mountains of Colorado, feeds those reservoirs. The snowmelt supplies water to millions of people downstream. Yet the forecasted runoff for Lake Powell is just 28 percent of average levels.
"This wouldn't be a concern if Lake Powell and Lake Mead had more water in them, but they are already at critically low levels," Bolinger says.
The record lowest inflow for Lake Powell was in 2002, during a historic drought for the West. But Bolinger notes that Powell and Mead were "quite full at the time," and believes there's a chance this year could rival the record.
"We have not recovered from that 2002 drop," she says. "I am extremely concerned about what this is going to mean for Lake Powell and Lake Mead."
Ripple effects on recreation, ranching, wildfires
Some parts of Colorado rely on snowpack as a central water source. Sonja Chavez manages the Upper Gunnison River Water Conservancy District, where snowpack levels are around half of normal. With less snow melting off quicker, Chavez said it's shortening the recreational season. If the snowpack was above-average, she said there could be six months of a season on the rivers.
"When you're in drought like we are right now, that season is concentrated into maybe four months," she said. What's more, she said, low river flows can mean bad water quality from higher concentrations of metals and other contaminants.
The lack of snow and monsoon rains also has a big impact on ranchers in the area, who are reporting lower hay production and smaller herd sizes.
"So this year we're starting to see our producers reduce their number of their cattle herd, and that has trickling economic effects throughout our basin," she said.
Chavez said the federal Bureau of Land Management has reported that water wells drilled on federal grazing land are starting to dry up. "The groundwater supplies and levels are actually falling," she said. "The city of Gunnison is actually dependent upon groundwater well supplies for our municipal water uses."
Chavez said there's a sense of urgency for water managers to plan for worst-case scenarios. She said more people have moved to the Gunnison area because of the COVID-19 pandemic allowing for remote work, and the water rights on those homes are newer.
"Some of those junior water right holders, they just may not get their water at all which is a concern," Chavez said.
Another symptom of snow disappearing from the landscape earlier is an extended drought and fire season.
"The earlier the snow melts, the drier the landscape becomes in that late summer period before fall rains sort of drown the system again," said Kelly Gleason, who researches eco-hydro-climatology at Portland State University.
The dried vegetation creates fuel sources primed for wildfires. And the feedback loop continues. Later, snowpack that collects in recently burned areas of the forest collects black carbon and is exposed to more sunlight.
"That blackened gunk acts like a black T-shirt on a sunny day, absorbing solar radiation," Gleason said.
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