Colorado is in the grips of a statewide drought.
Rivers are down, reservoirs are below average and snowpack is minimal.
Water managers and scientists say it is too early to tell if slow snowfall and the residual effects of a dry summer will affect next year’s water resources in Southwest Colorado, but they will be watching abnormally high temperatures and La Niña closely.
“I think the message needs to be this is the very beginning of winter,” said Steve Wolff, general manager of the Southwestern Water Conservation District. “We get our biggest snowfall as far as water content in March and April, so we’re a long way off from knowing we’re in trouble. But given the last two dry years we’ve had, we certainly need to be prepared and talking about ways to ensure we’re prepared if we do have another very dry year.”
It’s not odd for water resources to be scarce in November, December and January before snow replenishes the drain of summer and fall. Stream flows and reservoirs usually hit their annual lows around this time of the year.
Even for early December, water is in short supply.
Data from the Southwester Water Conservation District shows the Animas River is running at about two-thirds of its normal flow and the Piedra River near Arboles is flowing at a third.
Elsewhere, the numbers are worse, with the Mancos River near Towaoc at 10% of its average flow and Los Pinos River near Ignacio at less than 5%.
Some of these streams are low because reservoirs upstream are trying to restock after a long and dry summer, Wolff said. But reservoirs aren’t faring much better.
Navajo Reservoir sits at 67% of its usual water storage, and Lake Powell is less than half its early December average, according to Colorado Climate Center data.
Locally, Vallecito Reservoir is at 60% of its average and 26% of its storage capacity, and McPhee Reservoir is at 65% of its average and 43% of its capacity, said Robert Genualdi, the San Juan and Dolores River division engineer for Colorado’s Division of Water Resources.
“I think it’s just a reflection of the very dry summer we had,” Wolff said.
The picture for next year might seem dire given all the water that needs to be recharged, especially because early season snow-water equivalent in the San Miguel, Dolores, Animas and San Juan basins is 69% below average.
But a dry year is far from certain.
As Wolff points out, snow accumulates most in Southwest Colorado in February and March and snowpack peaks in early April.
“We tend to get a lot of our snow a little later in the winter season,” said Gigi Richard, a Fort Lewis College geosciences professor and director of the Four Corners Water Center. “By Dec. 1, not having much snowpack is not a huge concern.”
She is closely watching abnormally warm temperatures, limited precipitation so far this fall and La Niña for a better idea of what water resources will look like next year.
According to the Colorado Climate Center, parts of La Plata, Archuleta, Mineral and Hinsdale counties have recorded their warmest November ever.
Southwest Colorado as a whole has had a significantly warmer-than-average fall in tandem with less precipitation than usual, according to National Oceanic and Atmospheric Administration and Colorado Climate Center data.
“The biggest impact that warm temperatures and no snow or no precipitation has is that soils really dry out,” Richard said.
Dry soils limit snow accumulation and reduce the water storage that feeds rivers and reservoirs.
Soils dried out during the past year will have to soak up early-season snows until they replenish their capacity.
“You can think of our mountains as a big sponge, and we want that sponge to be wet and full of water,” Richard said. “If we have long periods with no precipitation, really dry air and higher temperatures, that sponge starts to dry out. If we go into the snow season with a dry sponge, we’ve got to fill that up again before we start to get runoff in the stream.”
Climate change is in part responsible for dry soils because as temperatures warm, soils dry out more quickly, she said.
Climate change also shifts the hydrologic cycle, melting snow earlier, lengthening the growing season and boosting evaporation and transpiration.
“The net result is we end up with less water in the rivers, which we’ve seen for the last two years throughout the Upper Colorado River Basin,” she said.
La Niña this year could also compound the effects of dry soils and climate change.
During La Niña, cold water in the Pacific Ocean shifts the jet stream northward.
As the jet stream goes northward, so do the storms. The Pacific Northwest and Canada get heavy rains and flooding while the Southwest faces drought.
The pattern has already begun to show itself this year.
Seattle recorded its wettest fall on record and western Washington and British Columbia have dealt with catastrophic floods over the last few months.
If the Pacific Northwest is a sign, La Niña could upend water resources in Southwest Colorado, but Richard said any early-season effects shouldn’t be concerning.
“Even if storms end up tracking further north, we could still end up with a few good storms that give us a decent snowpack,” she said. “A La Niña year doesn’t mean all hope is lost. It’s just more likely that more storms will miss us.”
Richard noted that even a few big storms could bring enough snow to recharge water in the region.
How all of this plays out over the next few months will determine whether Southwest Colorado faces significant water shortages again next year.
“We rely on storing our snowpack and using that water throughout the year for irrigation, for agriculture and for municipal and domestic use,” Richard said. “The city of Durango doesn’t have a big storage reservoir. We’re relying on the perennial flow in the Florida and Animas rivers for our water supply.”
Managers like Wolff are already thinking about next year’s water and the potential effects of dry soils and La Niña.
“Anybody who deals with water knows the poor two years we’ve seen and what would happen if we have another really bad year,” Wolff said. “Hopefully, we get a good snowpack, but we need to be thinking about those things right now.”
ahannon@durangoherald.com
