Massive rain events have brought temporary relief to some drought-stricken parts of the Upper Colorado River Basin, but these have also caused severe flooding and damage, especially in the Four Corners region.
The San Juan River has seen some of its highest flows on record, and Navajo Lake’s elevation jumped by 35 feet the weekend of October 24, after multiple storm systems from the Pacific Ocean converged. Parts of the San Juan River saw between five and ten inches of rain over just a couple days, and both the Animas and Dolores rivers saw their fifth highest water levels on record.
Those events were compounded the following weekend, when Archuleta County saw another two inches of rain in a little over 24 hours and La Plata County saw four inches of rain over two days. The flooding closed roads, caused power outages, and prompted evacuations in both counties.
This is the second year in a row that the Four Corners has seen heavy rain and flooding, though this year was more severe than last fall.
Seth Arens, a scientist with the Western Water Assessment, said these storm systems are likely driven by the very strong El Niño pattern over the Pacific Ocean, driving hurricanes and tropical storms.
He said this autumn was likely anomalous, but extremely wet autumns could be more common in the future.
“If this wet fall is, in fact, associated with a very strong El Niño, we'll probably see more of these very strong El Niños in the future, so then we may see more weather patterns like that,” he said. “But this is a relatively extreme precipitation that we've been seeing over the last two months.”
According to Arens, though the El Niño Southern Oscillation pattern has long been occurring in the Pacific Ocean, this kind of very strong El Niño is a relatively recent phenomenon, mostly taking place over the past fifty years. He said scientists will need more data to understand what implications these systems will have on forecasting in the future.
Russ Schumacher, Colorado’s state climatologist, said there will need to be more research as to how human-caused climate change has influenced these patterns, but this is consistent with what scientists expect of climate change.
“What we've seen in Western Colorado is we went from flood, to punishing drought, back to flood, and those increased hydrologic extremes is something that is a pretty robust expectation of climate change,” he said.
He says some parts of the region, like Colorado’s San Luis Valley, have seen rainfall that climatologists would consider to be 1-in-100-year -, or even 1-in-1000-year events.
Rain replenishes reservoirs, but it’s not enough
The rainfall did ease drought conditions in the Four Corners region, with some areas recording no drought at all on the U.S. Drought Monitor.
Those rains increased water storage in some of the basin’s largest reservoirs: Navajo Lake on the Colorado-New Mexico state line saw its levels jump 35 feet or by 360,000 acre feet of water, and Lake Powell’s elevation increased by 14 feet, or 823,000 acre feet.
But some parts of the Upper Colorado River Basin are still in drought. For example, the headwaters of the Colorado River are still in the U.S. Drought Monitor’s worst category: exceptional drought. Blue Mesa on the Gunnison River is still only 19% full, according to the Bureau of Reclamation.
Soil moisture has also increased significantly across the basin, which is positive heading into winter. Arens said it’s always better to go into the snow-covered season with wet soils.
“That way when the snow begins to melt, that melting snow doesn't have to fill up the dry soil, the soil's already wet,” he explained. “So when that snow melts, it then pushes water out through the near surface soil areas and into streams.”
That could potentially mean a more efficient runoff than what we’ve seen over the past couple of years, which means that a higher percentage of the water stored in the winter snowpack actually makes it into rivers and streams come spring.
But any long-term drought relief will rely on a robust snowpack, and that’s dependent on temperature. Even if El Niño brings a lot of precipitation, if this winter was as warm as last winter, the region could be looking at another weak snowpack.
“One really good snow year can fill those reservoirs back up, so if that's what we get, that would go a long way to helping that,” said Schumacher. “But then the flip side of that is, a second bad snow year would make things really, really bad because those reservoirs, in the grand scheme of things, just aren't that big.”
He says the El Niño weather pattern tends to bring wet autumns to Colorado, but the correlation between El Niño and snowy winters is much weaker, and that makes it difficult to predict what kind of snowpack this winter will bring.
Copyright 2026 Rocky Mountain Community Radio. This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah, and New Mexico, including Aspen Public Radio.
