When the waters of the St. Vrain came pouring over its banks one night last month, they ripped out huge trees, tore through homes along Apple Valley Road, cut new channels through parks and yards, and rushed through some downtown neighborhoods in Lyons, Colo., with particular force.
At David Tiller's small bungalow on Park Street, the "river" – normally a lightly flowing creek – overflowed its banks and gushed into the recording studio he had built in his backyard. Shortly after he, his wife, and their 5-year-old son escaped to higher ground in their van, the river ripped through their house with enough force to blow out the front walls, churn furniture as though it were in a washing machine, and wash the neighbor's house off its foundation and into theirs. Two weeks later, as Mr. Tiller and his sister picked through the wreckage, both the home and recording studio were half full of a toxic mix of mud, sewage, and river debris.
The flooding that hit northern Colorado between Sept. 11 and 15 affected 20 counties and an area of nearly 2,000 square miles, but it hit certain towns and neighborhoods with unusual severity. Now, towns like Lyons, one of the worst hit, are having to make tough decisions – whether to reroute rivers back to their former channels, whether to allow rebuilding in all the areas that flooded, and how to make the towns more flood-resistant in the future. At the same time, residents like Tiller are wrestling with agonizing decisions of their own. About 2,000 homes were destroyed in the region hit by the flood.
The state of Colorado faces an even larger task – restoring access to isolated communities. Some 200 miles of state highways and about 50 state-maintained bridges have been severely damaged or wiped out, many in challenging mountain terrain. It's a daunting undertaking that will cost hundreds of millions of dollars and will involve competing goals of speed, economy, and disaster mitigation and planning.
Colorado Gov. John Hickenlooper (D), who has said he wants to rebuild "stronger," has set a Dec. 1 deadline for rebuilding as much as possible, before winter sets in. Overall, though, the process will take years.
No doubt many decisions will be tough, although there could be an upside.
"The silver lining with events like this is you do have the opportunity to redo things differently – the layout of roads, the layout of towns," says Michael Gooseff, a professor of hydroecologic science and engineering at Colorado State University in Fort Collins. "Mother Nature has reset the playing field for us."
In many ways, Colorado's task is similar to the one Vermont grappled with after the storm Irene hit two years ago.
Like Colorado, Vermont is a mountainous state, and the deluge of rain poured into narrow valleys, washing away roads and bridges. The state lost some 500 miles of roadway and more than 30 bridges.
"The kind of flooding we had, and that Colorado is experiencing, [caused] erosion, tremendous erosion. The power of the water just ripped apart roads, bridges, and many, many homes and businesses," says Sue Minter, deputy secretary at Vermont's Agency of Transportation.
As in Colorado, Vermont was up against a looming winter season, when construction is largely forced to halt.
Ms. Minter was part of a delegation from Vermont that flew to Colorado shortly after the flood to share some of what they've learned with their Colorado counterparts.
Among the suggestions, according to Minter: Restructure agencies to become regional command centers, redeploy employees to best address the mission of rebuilding infrastructure, and put an "incident command system" in place – suggestions Colorado has largely adopted.
In Vermont, rebuilding and permitting were expedited in the immediate aftermath of the flooding. But that goal of speed, Minter notes, doesn't have to be at odds with careful planning.
Her advice to Colorado officials: Do everything possible in the short term to get roads passable. Then, once winter has passed, take a closer look at all the projects with an eye toward rebuilding for resilience to withstand potential disasters.
"In this moment, they need to get those roads up," Minter says. "But then they need to go back and think long term."
Once winter had passed in Vermont, a team that included transportation agency officials, natural resource experts, and geomorphologists revisited more than 600 sites to evaluate them. The team ultimately concluded that about half needed more rebuilding or repositioning to make them stronger.
Some of the questions looming for Colorado communities include just how much risk to take on and what sort of future disasters to plan for.
Weather experts are calling the storm that hit, in terms of the amount and timing of rainfall, a "thousand-year storm" – meaning it has a 0.1 percent chance of occurring in any given year. The flooding, on the other hand, was more in line with a 100- or even 50-year flood, depending on the spot.
But as extreme weather events occur with more frequency around the globe, some geologists say the accuracy of relying on past data to predict future events is in doubt.
So was this really a thousand-year storm? Or could Boulder, Colo., or surrounding communities be hit by even worse flooding in the coming decades?
"If this has a 0.1 percent chance of happening, one could say I'm going to take my chances; it's very unlikely this is going to happen again even in the next 100 years," Professor Gooseff says. "But I'm starting to wonder if ... we're moving into this new regimen, where the next 100 years won't look like the last 100 years, and we can't rely on old records."
Gooseff says that while a lot of the discussion has centered on the speed of rebuilding, he'd like to see more attention paid to doing it wisely – really thinking about the layout of the flood plain.
Many of these issues have come into sharp focus in Lyons, a small community of 2,000 situated between Boulder and Estes Park, Colo., known for bluegrass and folk-music festivals.
The two branches of the St. Vrain meet in Lyons, but in many places, they no longer flow where they did. At one point in town, a bridge now spans a dry riverbed. Just in front of it, the river flows through a stretch of obliterated highway. A new creek cuts through Park Street, hampering access for Tiller and other residents, whose flooded homes lie beyond it.
In other areas, the river is running in its natural channel, but has also split off to run in parallel channels.
Moreover, the creeks cut enormous new channels through normally dry areas that are a concern for future flooding, or even for usual spring runoff, engineers say.
"The obvious thing is to put [the river] back where it was," says Scott Shipley, an engineer from Lyons who designs white-water parks and is helping the town with its current decisions. Leaving the river in its new channels isn't necessarily safer, Mr. Shipley says, and in many cases produces major complications involving water rights, ditch rights, and property rights.
But restoring the river to its former path could be tricky – and expensive. And to the extent that engineers can find places to leave buffers – places where the river can spread out into wetlands and flood plains, alleviating pressure downstream – it will be better for future flooding, Shipley says.
"Part of what we're trying to do is build this town back better than it was," he says.
At this point, essentially the entire town of Lyons is evacuated since all utilities – water, sewage, electricity, gas – were lost in the flood. The town's public works building is in shambles, and weeks after the flood, the city was still trying to locate water mains.
Power and gas have now been restored in some areas, so that some businesses can resume minimal operations, but the town has warned that the businesses assume risk for any fires.
But even as the town struggles to get services back, residents – who have been allowed back in during the day with a pass – are struggling with many of their own questions about how, or if, to rebuild.
On Park Street, one of the worst-hit sections of town, rumors were flying that rebuilding might not even be allowed or that the county might decide to buy residents out and repurpose the land.
"We don't know if we can rebuild, or what the town will decide," Tiller says. "It's the golden question."
Tiller, a gentle man who surveys damage to his property with a Zen-like calm, lost virtually everything in the flood and didn't have flood insurance. He and his wife are musicians in the band Taarka, and they bought their house outright several years ago with a small inheritance.
"Having this house allowed us to make a living as musicians," he says. "Without it, we don't really have that option."
The night of the flood, he rescued a few of their most valuable instruments, some microphones and recording equipment, and his good camera. Everything else – from valuable 17th-century furniture that had belonged to his grandmother to his son's favorite stuffed panda – was swallowed up by mud.
Rebuilding in a place that flooded so badly isn't ideal, but all Tiller and his wife have left is the land they own and whatever can be salvaged from the home. So if rebuilding is allowed, that's what they'll do, he says.
"We might not have a lot of choice," Tiller says. "That's where our money is, and we're not going to get whatever that land is worth back."
The Federal Emergency Management Agency (FEMA) has been assessing damaged properties, and Tiller says it is offering rent assistance of $1,068 a month for his family. It might also give as much as $32,000 to help repair damage, although Tiller thinks that figure is only about a fifth of what they'll need.
Overall, FEMA has already approved $36.2 million in individual assistance to Colorado homeowners affected by flooding and $34.2 million in housing assistance.
Just up the street from Tiller, Joe Meckle lost not just his home but his business as well, a chiropractic clinic he ran out of his house. Dr. Meckle did have flood insurance, but it won't cover any of the damaged belongings – including expensive X-ray machines and chiropractic tables that were destroyed.
"This town was a Shangri-La, man," he reminisces ruefully, as he swaps stories with neighbors outside his mud-filled home and debates what happens next.
Still, he says, "Don't cry for me. I'm young enough that I can recover."
When some Lyons residents returned to their homes to survey the damage, they were pleasantly surprised it wasn't worse.
One level of Parker Johnson's home along Apple Valley Road flooded, but the rest of the house stayed dry. The house smells musty, and Mr. Johnson and his wife have been examining their belongings and purging everything ruined – a process that he says is somewhat of a blessing.
Given what he saw when they evacuated in the middle of the night with their three young children, with the St. Vrain rerouted through their front yard and rising fast, "our particular situation is better than I had feared by a long shot, so I'm feeling kind of overwhelmingly fortunate," he says.
For many of his neighbors, on the other hand, the damage is much worse than they anticipated. Some neighbors – especially those who are older and retired – have told Johnson they're not sure if they have the energy or will to return and rebuild, and they may move elsewhere.
Some of the decisions the town and county will face – especially about where to allow rebuilding – may be tough, Shipley acknowledges. It may not make sense, for instance, to put a trailer park in the same location that was devastated by the flooding.
"In some ways [the flood] was the worst news for the people who can least afford it," Shipley says. But he says he believes that the town is not only committed to making itself less vulnerable to future flooding, but also to finding creative ways, such as land swaps, to help those residents who may be harmed.
"These are tough decisions to make, and private property factors into it, land use factors into it, and you don't want to make decisions that make things worse," Shipley says. "But what I've heard is that we're committed to low-income housing, and we're committed to making this an affordable place to live.... I've heard nothing but smart planning from this town."
Right now, the first order of business is simply to get Lyons's basic services and utilities running again, so residents with less-damaged homes can move back, and local businesses – many of which operate on a narrow margin and are taking an enormous hit with the closure – can reopen.
"What we're seeing is the slow death of our downtown as we wait for the infrastructure to come in," says Shipley, who guesses that about half of those businesses may be gone, or "horribly reeling," by the time they can reopen.
Town officials have resisted giving a date when utility services will be restored, but they say the worst-case scenario is Christmas, and they hope it will be sooner.
Residents like Tiller and Meckle are also in a holding pattern, waiting to hear what will be decided about the land where the worst flooding occurred.
But they and other Lyons residents say the biggest blessing to emerge from the disaster has been the extraordinary sense of community support they've seen.
"It's the only thing that keeps us going," Meckle says.
Tragedy has helped bring people even closer, Johnson says.
"One of the silver linings for our community has been a bonding across socioeconomic and political divides that otherwise kept people to their own tribe," he says.
"Through the bonding of sharing this collective experience together, people are forgetting what their positions were about things that are less important than our shared humanity. I think that's a big deal."