Butch Knowlton looks at a floodplain map of La Plata County, and his mind envisions the worst-case scenario: all those homes, all those people.
As director of La Plata County’s Office of Emergency Management, Knowlton assumes the worst and plans accordingly. But the harsh reality of natural disasters is that only so much can be done.
“As a community, we’re poorly prepared,” he said. “And I say that because there’d be such a large impacted population, it would be difficult for local government to take care of all those people.”
Last year, all hands were on deck preparing for what many believed would be a catastrophic wildfire season as a result of extreme drought conditions in Southwest Colorado. And those fears were realized June 1 when a small spark climbed up a hillside north of Durango and went on to burn more than 54,000 acres.
This year, it is a different story. Heavy snowfall throughout winter and early spring has everyone’s attention turned to the potential of widespread flooding across La Plata County, especially for those who live along the banks of the free-flowing Animas River.
“It’s worth watching because there are a lot of homes in that floodplain,” Knowlton said.
Settling in safetyWhen Durango, and the Animas Valley to the north, were settled in the late 1800s and early 1900s, homesteaders had the good sense to build their homes and ranches a safe distance from the high watermarks of the Animas River.
But as future development occurred in the mid-20th century, homes started to inch ever closer to the river’s banks.
“It almost seems like people wanted to gamble a little bit more,” Knowlton said. “Because the fact is, one day you’ll get a high-water event that will impact homes and buildings.”
In September 1970, that’s exactly what happened.
During a relentless rainstorm, more than 3 feet of rain fell in the San Juan Mountains, causing the Animas River to reach nearly 12,000 cubic feet per second. (For reference, the Animas River usually hits a peak flow of about 4,700 cfs in early June at the height of spring runoff).
The impacts of the flood served as a sort of reckoning to officials in La Plata County and the city of Durango, that with more development in flood-prone areas, it was time to start adopting regulations to better protect residents and homes.
In the late 1970s, the first floodplain regulations were implemented for new development along the Animas River, as well as Vallecito, Hermosa, Junction and Lightner creeks.
1 in 100 chanceThe basic principle of the floodplain regulations haven’t changed over the years: New structures built in a floodplain must be elevated 12 inches above the high watermark of the 100-year flood.
A “100-year flood” is a metric used for a high-water event that has a 1% chance of happening.
In recorded history, this event has happened only one time in Durango.
Unprecedented rainfall in October 1911 bombarded Southwest Colorado, causing the Animas River to surge to 25,000 cfs. Deemed “the worst flooding in history” of the region, the floods caused deaths, destroyed bridges and left Durango cut off from the rest of the world.
If the Animas were to rise to its 100-year flood potential today, there would be a whole new path of destruction, Knowlton said.
A number of homes in the Animas Valley would be damaged. Dalton Ranch, for instance, would be under water. Homes along Junction Creek could be swept away. Burger King and China Café in downtown Durango could be submerged. And even the Santa Rita wastewater-treatment plant could be affected.
“When you start adding it all up, it’s a cascading event,” Knowlton said. “No pun intended.”
Spring rains a riskDespite the significant amount of snowpack in the San Juan Mountains – about 155% of historic averages as of Thursday – there is relatively low risk of massive flooding from spring runoff, said Greg Smith, a hydrologist with the Colorado River Basin Forecast Center.
The actual water flow for the Animas River to be considered in a flood stage is 10,500 cfs. In 109 years of recorded history, the Animas from April to July has exceeded that amount only three times, in 1927, 1941 and 1949.
Instead, the river is far more at risk of extreme flooding in the fall as a result of torrential monsoon rains, Smith said.
“But that doesn’t mean you won’t have high flows this spring,” he said.
Indeed, the forecast center predicts the peak spring runoff of the Animas River to reach the top 25% or 30% of 109 years of records.
And despite historical precedent, that doesn’t mean Durango is in the clear of flooding this spring. It all depends on the weather, Smith said. If temperatures rise quickly, and rains hit the unmelted snow, it could bring down a large amount of water.
“That’s a recipe that causes problems,” he said.
If things get badIf flooding does happen, and local resources are maxed out, it sends off a sort of SOS signal to the state and then federal emergency responders.
The most recent and helpful example of present-day flooding was in 2013, when 24 counties on the Colorado Front Range were hit by fast-moving water.
Micki Trost, a spokeswoman with the Colorado Division of Homeland Security and Emergency Management, said there were two major takeaways from the disaster: Residents should be signed up for emergency alerts and have their homes insured.
“People really need to be prepared for their own personal recovery,” she said.
State and federal partners, however, do have a plan in place for things like emergency shelters and evacuation centers should the big one hit.
Brian Hvinden, a spokesman in Denver for the Federal Emergency Management Agency, said the Durango area is on the agency’s radar, especially since the burn scar of the 416 Fire has created unprecedented flooding danger for a host of residents.
“We’re absolutely aware of it,” he said.
Personal responsibilityThe floodplain maps for the Animas Valley haven’t been updated since the late 1970s, Knowlton said, and it is possible waters could reach areas not previously considered at risk.
David Sutley, a senior hydraulic engineer for FEMA, said updated floodplain maps for the Animas Valley should be released by 2020. The maps will be able to tell, better than ever because of enhanced technology, what areas are most prone to high-water events.
But increasingly, experts’ previous definitions of 100-year or 500-year floods are being thrown out the window, Knowlton said. In Houston, for instance, the city was hit with three 500-year flood events three years in a row, 2015 through 2017.
“With climate change, are we ever going to see storms in tune with what’s projected or will it be in excess of what’s projected?” Knowlton said.
Knowlton said local officials are watching weather conditions closely, just as they watch all potential disasters in La Plata County closely. He wishes residents did a little more of the same.
“Your mind could go crazy thinking about all the things that could affect a community,” he said. “And whether it’s a snowstorm or flood, people are just not prepared to take care of themselves, and that’s the sad part, because if a government gets overwhelmed and can’t take care of you, the only solution is to be prepared as an individual.”