Lyons, Colo. - Emergency airlifts of flood victims waned Tuesday, leaving rescue crews to search systematically through the nooks and crannies of the northern Colorado foothills and transportation officials to gauge what it would take to rebuild the wasted landscape.

More than 3,000 people have been evacuated by air and ground since last week's devastating floods, but calls for those emergency rescues are dwindling, federal and state emergency officials said.

With hundreds of people still considered missing, military rescue crews have met to identify new areas to check and others to recheck.

"They've kind of transitioned from that initial response to going into more of a grid search," Colorado National Guard Lt. Skye Robinson said.

In one of those searches Tuesday, Sgt. 1st Class Keith Bart and Staff Sgt. Jose Pantoja leaned out of the window of a Blackhawk, giving the thumbs-up sign to people they spotted on the ground while flying outside of hard-hit Jamestown.

Most waved back and continued shoveling debris. But then Bart spotted two women waving red scarves, and the helicopter descended.

Pantoja attached his harness to the helicopter's winch and was lowered to the ground. He clipped the women in, and they laughed as they were hoisted into the Blackhawk.

After dropping off the two women at the Boulder airport, the Blackhawk was back in the air less than a minute later to resume its search and rescue work.

The state's latest count has dropped to about 580 people missing. The number continues to decrease as the stranded get in touch with their families.

One of the missing is Gerald Boland, a retired math teacher and basketball coach who lives in the damaged town of Lyons. Boland's neighbors, all of whom defied a mandatory evacuation order, said Boland took his wife to safety Thursday then tried to return home.

Two search teams went looking for him Monday.

"He was very sensible. I find it amazing that he would do something that would put himself in harm's way," neighbor Mike Lennard said. "But you just never know under these circumstances."

State officials reported six flood-related deaths, plus two women missing and presumed dead. The number was expected to increase. It could take weeks or even months to search through flooded areas for the dead.

State and local transportation officials have begun tallying the washed-out roads, collapsed bridges and twisted railroad lines. The rebuilding would cost hundreds of millions of dollars and take months, if not years.

Initial assessments have begun trickling in, but many areas remain inaccessible and the continuing emergency prevents a thorough understanding of the devastation's scope.

"The numbers are going to change tomorrow as we get into more places, and the numbers are going to change the day after that," Federal Emergency Management Agency spokesman Ricardo Zuniga said.

Northern Colorado's broad agricultural expanses are especially affected, with more than 400 lane-miles of state highway and more than 30 bridges destroyed or impassable.

A Colorado Department of Transportation helicopter crew has been surveying damage, department spokesman Ashley Mohr said.

County officials have started their own damage tallies: 654 miles of roads in Weld County bordering Wyoming, 150 miles of roads in the Boulder County roads foothills, along with hundreds of bridges, culverts and canals.

Larimer County hasn't begun its assessment, with approximately 600 people there still awaiting rescue, but officials said the widespread damage leaves little doubt about what the price tag will be.

"It's going to be astronomical. There's no way around it," Capt. Ralph Kettle with the Poudre Fire Authority in Fort Collins.

Dale Miller, road and bridge director for Larimer County, said it could compare to the damage wrought by a 1976 flood that killed 144 people. It took two years to rebuild after that disaster.

State officials have put initial estimates at more than 19,000 homes damaged or destroyed throughout the flooded areas.

Federal aid is forthcoming - it's not known how much yet - after President Barack Obama's disaster declaration. An initial $5 million has been pledged.

More than 6,400 disaster victims have applied for federal assistance, with more than $430,000 in individual assistance approved so far, FEMA officials said.