The search for people stranded from the Rocky Mountain foothills to the plains of northeastern Colorado grew more difficult Sunday, with a new wave of rain hampering airlifts from the flooded areas still out of reach.

From the mountain communities east to the plains city of Fort Morgan, numerous pockets of individuals remained cut off by the flooding. With rain impacting helicopter searches, rescuers trekked by ground up dangerous canyon roads to reach some of those homes isolated since Wednesday.

More than 1,750 people and 300 pets have already been rescued from communities and individual homes swamped by overflowing rivers and streams.

The surging waters have been deadly, with four people confirmed dead and two more missing and presumed dead after their homes were swept away.

Hundreds of people have still not been heard from, but with phone service being restored to some of the areas over the weekend, officials hoped that number would drop as they contacted more stranded people.

The additional rain falling on ground that has been saturated by water since Wednesday created the risk of more flash flooding and mud slides, according to the National Weather Service.

Days of rain and floods have transformed the outdoorsy mountain communities in Colorado's Rocky Mountain foothills from a paradise for backpackers and nature lovers into a disaster area with little in the way of supplies or services. Roadways have crumbled, scenic bridges are destroyed, and most shops are closed.

'These beautiful places, it's just brown mud'

In Lyons, the cars that normally clog main street have been replaced by military supply trucks. Restaurateurs and grocers in Lyons were distributing food to their neighbours as others arrived in groups carrying supplies.

Chris Rodes, one of Lyon's newest residents, said the change is so drastic that he is considering moving away just two weeks after settling there.

'There's no gas, no toilet paper, no milk. They got food trucks to Safeway yesterday. Within about an hour, everything was emptied out.' - Renee Maher, clerk, Stanley Hotel 

"It's not the same," Rodes said. "All these beautiful places, it's just brown mud."

In Estes Park, 30 kilometres from Lyons, hundreds of homes and cabins were empty in the town that is a gateway to Rocky Mountain National Park. High water still covered several low-lying streets. Where the river had receded, it had left behind up to 30 centimetres of mud.

Estes Park town administrator Frank Lancaster said visitors who would normally flock there during the golden September days should stay away for at least a month, but it could take a year or longer for many of the mountain roadways to be repaired.

Meanwhile, people were still trapped, the nearby hamlet of Glen Haven has been "destroyed" and the continuing rain threatened a new round of flooding, he said.

"We are all crossing our fingers and praying" Lancaster said.

Ironically, the massive Estes Ark — a three-storey former toy store designed to look like Noah's Ark — was high and dry.

"I don't know if it's open anymore, but soon it's going to be our only way out," joked Carly Blankfein.

Supplies of gas and groceries had been running low until Route 7 was recently reopened. On Sunday, people were lined up at the one gas station where a tanker had arrived.

At the town's historic Stanley Hotel, the inspiration for Stephen King's horror story The Shining, clerk Renee Maher said the hotel was nearly empty. Though it sits on a hill overlooking town, 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.

"There's no gas, no toilet paper, no milk," Maher said. "They got food trucks to Safeway yesterday. Within about an hour, everything was emptied out."

Despite the mess, some people staying in town turned out for the Stanley's nightly ghost tours.

"They said they came because they had nothing to do," Maher said.

'It's truly unsafe'

In Boulder, often called America's fittest town, Mayor Matt Appelbaum warned people to stay out of the wide-open spaces that ring the city.

"I know that people are eager to get out there again, but it's truly unsafe." he said. "Places that I've known and loved for 30 years are gone."

Boulder remained a refuge for evacuees from the more isolated mountain towns. These refugees filled a church, a YMCA and a high school and crashed on couches around town. Meanwhile, water continued to back up in some parts of town and a water treatment plant remained down Sunday.

But the town was bouncing back. Libraries and recreation centres have reopened. Students are again spilling out of cutesy restaurants on Pearl Street, and classes at the University of Colorado are expected to resume Monday.

Meanwhile, in the neighbouring state of New Mexico, another round of rain moved across the state on Sunday, renewing the threat of heavy runoff from already saturated soils and flooding in low areas as residents faced a major cleanup effort from damage left in the wake of days of relentless rain.

The National Weather Service issued a flash flood watch for much of central and northern New Mexico. The flooding killed at least one person — a man who died after his car was submerged when his car was washed into a ravine and carried nearly 1.6 kilometres from the road.

With files from CBC