By Jerd Smith | May 31, 2023
Climate change has come home to Durango, with a new study indicating that the once water-rich mining and railroad mecca is much drier than it once was, so dry in fact that the city can no longer depend solely on direct flow from the Florida and Animas rivers for a reliable supply of water.
Like other small towns in Colorado, Durango has very little water storage, enough to last for less than 10 days. It has always relied on its ability to pull water directly from the Florida River, using the Animas River as backup. But that is no longer possible, prompting the city to fast-track a major regional pipeline project to tap storage in Lake Nighthorse and to double down on conservation.
Larger cities often have water storage reservoirs that can carry them for months if not years during dry periods. But that’s not necessarily the case in smaller rural and mountain towns.
A new study of stream gage data conducted for Durango by the Silverton-based Mountain Studies Institute (MSI) shows that average annual precipitation in one of the town’s major watersheds has declined as much as 19.7% annually since the late 1980s and runoff, the water that eventually makes it to the stream, has dropped even more, as much as 35.7% in the Florida (pronounced Floreeeda) River watershed. The same trend, though to a much lesser extent, is also showing up in the Animas River watershed.
“It’s eye opening,” said Jarrod Biggs, Durango’s assistant finance director who has overseen much of the city’s recent water planning efforts. “It’s confirmation of what our anecdotal evidence has told us. It doesn’t go down to nothing, but it is a significant difference from where we were a decade or two ago.”
Jake Kurzweil, a hydrologist and associate director of water programs at MSI who conducted the study, said the declines help illustrate on a local level how watersheds have begun to dry out as the climate warms. The data also measures how much water the natural environment uses, essentially intercepting runoff before it can reach streams, which cities, farmers and industry tap for their water supply needs.
In the Florida River analysis, a measure known as the runoff ratio is markedly declining. The ratio is obtained by taking annual runoff and dividing it by precipitation.
“The runoff ratio is showing us how efficient the watershed is at generating water. Not only are we getting less precipitation, the efficiency of the watershed is also declining. My hypothesis is that we are well below the environmental demand for water,” Kurzweil said.
Similar trends are showing up in the Animas watershed, but right now they are not as alarming as those in the Florida. Kurzweil said because the Animas watershed is bigger and its terrain is more diverse, it is better protected from the harsh temperatures and strong sunlight that have driven the drying trends on the Florida River.
Peter Goble, a climatologist at the Colorado Climate Center housed at Colorado State University, cautioned that the region’s 1,200-plus-year megadrought likely exaggerates the level of declines seen in the MSI data. He also said that long-term climate warming forecasts don’t show dramatic drying trends in the next 30 to 40 years.
“[Kurzweil] is comparing a time when we scarcely had any droughts to a period that has been quite dry. Precipitation can vary widely and our climate models don’t show this clear drying signal…if anything climate models show that precipitation may increase just a little bit,” Goble said.
“Yes it’s getting warmer, yes we do need to be concerned about that, yes it does put pressure on our environmental systems. However I don’t like comparing [1985-1999 to 2010-2021] specifically because you are capturing the high side and the low side,” Goble said, referring to the time periods MSI used in its analysis.
Kurzweil acknowledges that the megadrought has exacerbated the drying seen in Durango’s river systems, but he said he thinks the trend will likely continue, in part because though Northern Colorado could see more precipitation as its climate warms, Southwestern Colorado could be drier because it is so much farther south.
The Florida and Animas rivers are part of the San Juan/Miguel/Dolores river basin. Regional officials are tracking the local trends closely.
Ken Curtis is general manager of the Dolores Water Conservancy District in Cortez, a 50-minute drive west of Durango. Curtis is working with a slate of forest, climate and water specialists to find ways to create healthier forests that are less prone to wildfires and better able to sustain water production as the climate continues to warm up.
“Clearly the southwest is a drier area than the northern parts of Colorado,” Curtis said. “Climatologically we’re closer to a desert and we are at lower latitudes.”
Durango’s Biggs said the city had been planning to build a pipeline from Lake Nighthorse, a federal reservoir built in the early 2000s, at some point in the future to provide access to more storage. But such a project, likely to cost tens of millions of dollars, had been seen as a long-term goal, not an immediate need.
The new analysis has prompted Durango to fast-track the project and to keep its eye on ongoing and new conservation efforts.
“Presenting the data to our decision makers compelled them to move ahead with something we had been thinking about for quite some time,” Biggs said.
“Now, we want to activate this water in the near term. We don’t want to be in a situation where in five years we need it and we still haven’t built the pipeline,” Biggs said.
Durango is working with regional partners including the Southern Ute Tribe, in Ignacio, and the Ute Mountain Ute Tribe, in Towaoc, as well as the U.S. Bureau of Reclamation and others to see if the pipeline can be built in the next five years and provide benefits to everyone in the region.
“We all know the future is uncertain, but Kurzweil painted a realistic picture that shows that everybody’s sentiments are true. We are going to have to do with less water…so in the same breath when we talk about a pipeline we also have to talk about conservation,” Biggs said.
And it’s not just conservation and storage. Local planners are also thinking about worst-case scenarios and emergency backups.
“It’s really tricky,” Kurzweil said. “When you’re trying to do municipal planning you need to look at not just the day-to-day but at the catastrophic. There is a real-life scenario on the Florida when supply is critically low, and a pipeline breaks and there is wildfire and an unplanned spill.”
“There is a universe where that exists. I hope it’s not ours,” he said.
Jerd Smith is editor of Fresh Water News. She can be reached at 720-398-6474, via email at firstname.lastname@example.org or @jerd_smith.
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