Crews plowed up to a foot of mud left standing along Estes Park's main street after the river coursed through the heart of town late last week.
"I hope I have enough flood insurance," said Amy Hamrick, whose friends helped her pull up flooring and clear water and mud from the crawl space at her coffee shop. Her inventory was safely stashed at her home on higher grounds, she said.
Emergency officials offered a first glimpse at the scope of the damage. Counties reported some 1,500 homes have been destroyed and about 17,500 damaged, according to an initial estimate released Sunday by the Colorado Office of Emergency Management.
The number of people still unaccounted for was dropping Monday as Larimer County officials said they had made contact with hundreds of people previously not heard from in flooded areas.
With rescuers reaching more pockets of stranded residents and phone service being restored in some areas, officials expect those numbers to continue to decrease.
"You're got to remember, a lot of these folks lost cellphones, landlines, the Internet four to five days ago," Gov. John Hickenlooper said on NBC's "Today" show. "I am very hopeful that the vast majority of these people are safe and sound."
The death toll remained at four confirmed fatalities and two missing and presumed dead.
Helicopter searches and airlifts resumed Monday as the sun broke through the clouds over the mountains. Rainy weather had kept the helicopters grounded most of the day Sunday and early Monday.
On Sunday, military helicopters rescued 12 people before the rain, and 80 more people were evacuated by ground, Colorado National Guard Lt. James Goff said.
In Estes Park, comparisons were drawn to two historic and disastrous flash floods: the Big Thompson Canyon Flood of 1976 that killed 145 people, and the Lawn Lake flood of 1982 that killed three.
"Take those times 10. That's what it looks like in the canyon," said Deyn Johnson, owner of the Whispering Pines cottages, three of which floated down the river after massive amounts of water were released from the town's dam.
Estes Park town administrator Frank Lancaster said this flood is worse than the previous ones because of the sustained rains and widespread damage to infrastructure across the Rocky Mountain Foothills.
Major road were washed away, small towns like Glen Haven were reduced to debris, and key infrastructure like gas lines and sewers systems were destroyed. That means hundreds of homes in Estes Park alone could be unreachable and uninhabitable for up to a year.
But there appears to be no loss of life in this gateway community to Rocky Mountain National Park, Lancaster said.
"We know there are a lot of people trapped, but they are trapped alive," he told people gathered at a Red Cross evacuation shelter Sunday.
The Office of Emergency Management is urging people who are stranded by floodwaters but are unable to communicate by phone or other means to signal helicopters passing overhead with sheets, mirrors, flares or signal fires.
Lyons was almost completely abandoned. Emergency crews gave the few remaining residents, mostly wandering Main Street looking for status updates, a final warning to leave Sunday.
Most of the town's trailer parks were completely destroyed. One angry man was throwing his possessions one by one into the river rushing along one side of his trailer on Sunday, watching the brown water carry them away while drinking a beer.
Rescues continued through the rain in any way possible, including by foot, all-terrain vehicles zip lines rigged to hoist people and pets across swollen rivers and creeks.
Even Estes Park's historic Stanley Hotel, a structure that was the inspiration for Stephen King's "The Shining," suffered damaged, despite its perch on a hilltop overlooking the town and the river.
Front desk worker Renee Maher said the ground was so saturated that water was seeping in through the foundation, and had caused one suite's bathtub to pop out "like a keg," Maher said.
The massive Estes Ark toy store, meanwhile, was high and dry. The two-story business designed to look like Noah's Ark was closed temporarily because of the surrounding flooding.
"Soon it's going to be our only way out," joked Carly Blankfein.
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