- NEW: Another person is presumed dead, which could bring the death toll to 6
- NEW: Sheriff chokes up talking about resilience of the community
- Boulder spared Saturday evening but faces rain Sunday
- Sheriff says authorities should be "realistic" about the chances the death toll will rise
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Boulder, Colorado (CNN) -- Rain was still coming down Sunday in Colorado, preventing aerial efforts to search for those missing from a devastating flood, authorities said.
"It's unlikely at this point that we'll be able to reach those who are stranded in the hard-to-reach areas," said Kim Kobel, a spokesperson for Boulder's Office of Emergency Management.
But rescuers continued their ground efforts, searching for what could be hundreds of people unaccounted for.
A tearful Larimer County Sheriff told reporters that what he's seen, even in the most devastated areas, has restored his hope.
Sheriff Justin Smith visited areas "somewhat cut off from the rest of the world," he said.
The roads and homes might be gone, but Smith said "inch by inch, mile by mile, community by community they are taking this stuff back."
Smith spoke of firefighters who pulled signs out of the mud and residents using their ATVs to rescue neighbors.
Still he couldn't begin to estimate the scope of the damage. "I've known these areas for 25 years," he said "I don't recognize some of them."
He and another official cautioned that the death toll would almost certainly rise.
It may already be as high as six.
Previously, four deaths were blamed on the flooding and a fifth person was presumed dead.
On Sunday, authorities announced another resident presumed dead -- an 80-year-old woman who suffered from injuries and was unable to leave her home.
Another 482 people remain unaccounted for, but authorities said that number could go down throughout the day.
Residents are still keeping a wary eye on the sky, as more rain is expected -- and could be enough to halt rescue efforts.
"We're going to be in for some steady rain over the next 12 hours," said Kobel. It shouldn't total more than 1 to 2 inches though. "So that's the good news."
Still, authorities worry that any additional water on ground that's already soaked by up to 15 inches of rain will cause more flooding and dislodge mud and debris.
Officials were working to plan the recovery.
Gov. John Hickenlooper said he spoke by phone with U.S. Transportation Secretary Anthony Foxx, who "was adamant that the $5 million that was released Friday was just the beginning" of federal assistance.
"We're going to come back and rebuild better than it was before," the governor said.
Hickenlooper said experts from Vermont will arrive this week to share lessons about improved road-building learned in the wake of Hurricane Irene.
How to help
Damage worth millions
Boulder County alone will need an estimated $150 million to repair 100 to 150 miles of roadway and 20 to 30 bridges, county transportation director George Gerstle said. The repair bill will be "10 to 15 times our annual budget," he said.
A helicopter surveillance mission Saturday carrying Hickenlooper and members of Colorado's congressional delegation was diverted twice to pick up people waving to be rescued.
After the officials' delayed arrival at a Boulder airport, U.S. Sen. Mark Udall promised a bipartisan push in Congress for federal aid for flood recovery.
President Barack Obama signed a major disaster declaration for Colorado on Sunday and ordered federal aid to supplement state and local recovery efforts in Boulder County.
Two teens killed
The four confirmed deaths included a man and a woman, both 19, who were swept away after leaving their car Thursday in Boulder County. Authorities said the woman left the car first, and the man jumped out to try to save her. Authorities recovered both bodies.
Another body was found in a collapsed home in Jamestown in the same county. Rescuers recovered another body on a roadway in Colorado Springs in El Paso County.
The other person presumed dead is a 60-year-old woman. Larimer County officials said witnesses saw her swept away by floodwaters that demolished her home.
Neighbors tried unsuccessfully to rescue the woman, said Nick Christensen, executive officer of the sheriff's office.
Her body has not been recovered.
CNN's David Simpson and Emma Lacey-Bordeaux reported from Atlanta; Nick Valencia reported from Longmont, Colorado. CNN's George Howell, Ana Cabrera, Jack Hannah, Janet DiGiacomo, and John Branch contributed to this report.