FEMA claims To make a claim with FEMA, call 800-621-3362 or visit disasterassistance.gov.

A major air rescue for the Boulder County foothills devastated by 100-year floodwaters is planned for Monday, with residents asked to use white sheets, reflective mirrors, flares and signal fires to alert helicopter pilots to their locations.

“The pilots are going to go anywhere and everywhere they can,” said Gabrielle Boerkircher, a spokeswoman for Boulder County. “People need to be prepared to be evacuated. They need to try to flag down the choppers in any way they can.”

She said residents should be ready with a bag of medications, clothes and other important items — and should wait until they get a signal to approach the helicopter after it lands. She acknowledged that many of those in need of rescue may not have phone or Internet service and won’t know the helicopters are on their way, but the county is doing everything it can to get the word out.

A time when the helicopters will start flying hasn’t yet been determined, but she said the goal is to take advantage of the clearer weather that’s forecast Monday. After a reprieve Saturday from the torrential downpours that had dropped nearly 15 inches of rain on Boulder beginning last Monday evening, Sunday’s nearly 2-inch rainfall and low-hanging fog grounded helicopters and complicated rescue efforts.

Boulder County was under a flood warning until 9 p.m. Sunday and, in north Boulder, both Twomile and Fourmile creeks were flooding Sunday afternoon, city officials said. But the rain Sunday didn’t produce significant flooding within the city or county.

The historic flood has killed at least three and left 235 unaccounted for in Boulder County. The flood also has caused at least $100 million to $150 million in damage to roads, bridges and other structures in the county, according to early estimates from the Boulder Office of Emergency Management.

Given the severity of the damage, President Barack Obama has signed a disaster declaration and ordered federal aid for Boulder County residents.

The action makes federal funding available to those affected by the flood, and Boulder County officials are urging people to make claims — even if they have flood insurance coverage — to help gauge the severity of the devastating floodwaters.

The aid can include grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses, and other programs to help individuals and business owners recover.

Boulder County Sheriff Joe Pelle on Sunday said the number of people unaccounted for doesn’t necessarily represent people who are definitively missing, but instead is a list of those who have not been in contact with loved ones.

“This information concerns the people who care for someone but can’t account for them,” Pelle said.

He said two detectives from his department have joined a search and rescue team in Jamestown to attempt to retrieve the body of a man believed to have died when his house collapsed.

But the rescue crew needs heavy equipment to start the recovery process, and Pelle didn’t know when his office would be able to get some up the canyon.

Officials estimate 35 bridges need to be repaired and said rushing floodwaters have damaged at least 100 miles of roads. Additionally, flooding has damaged at least 100 minor structures, such as walking bridges near Boulder Creek, said Liz Donaghey, a spokeswoman for emergency operations.

The $150 million damage estimate doesn’t include damage to private residences, officials said. Crews don’t yet have a damage estimate for city and county buildings.

Walls of water and mudslides have crushed homes in Boulder’s mountain towns the hardest, and search and rescue crews Saturday performed what is being called the largest aerial rescue since Hurricane Katrina.

More than 1,200 people have been evacuated so far.

Crews on Saturday were able to send helicopters into the mountain towns of western Boulder County as well as high-clearance trucks into Lyons to evacuate stranded residents, with Pelle calling the operation “an amazing 24 hours of saving lives.”

About 500 people were driven out of Lyons, but many of the other rescues Saturday were performed by helicopter as the National Guard staged an air rescue campaign from Boulder Municipal Airport.

Coroner Emma Hall on Saturday evening released the identities of two of the three people killed by the flooding in Boulder County.

Those victims were Wiyanna Nelson and Wesley Quinlan, both 19. Sheriff’s officials said the teens died after getting out of the car they were in on Linden Avenue and being swept away by the rushing floodwaters.

Hall has not yet identified the third victim claimed by the storm in Boulder County, but residents of Jamestown have said they believe it was former Jamestown Mercantile owner Joseph Howlett, 72. Neighbors fear Howlett was killed when his house collapsed in a mudslide Wednesday night.