State and federal authorities were surveying damage in flood-ravaged southwestern Utah Wednesday that was expected to exceed $3 million.

Washington County Sheriff Kirk Smith said Wednesday morning that about 20 homes, many of them valued at between $500,000 and $1 million, were washed away. Schools were canceled, and some regions were without telephone service on Tuesday.

Fall rains, combined with heavy snowmelt and additional rain over the past few days, swelled rivers and reservoirs throughout the region.

Gov. Jon Huntsman declared Washington County a state disaster area, a step toward acquiring federal aid. Smith said floods were rare in the area, and few homeowners had flood insurance.

"It's a situation that one must see to believe. It's truly a disaster area in some respects. Property has been lost, homes have been lost, families have been relocated," Huntsman said. "Small towns like Gunlock, with 350 people, have been completely isolated and cut off from the outside world."

National Guard helicopters airlifted people out of the Gunlock and Motoqua areas, said Chief Perry Lambert, a spokesman for the Washington County emergency operations center. The areas, northwest of St. George, were left stranded when a bridge was knocked out.

The Utah National Guard was also delivering supplies to those areas for remaining residents, he said. State and county officials throughout the region also were working to arrange medical care, water, food and shelter for the displaced, Huntsman said.

Smith said the water level had dropped 4 feet to 6 feet by Wednesday morning, bringing hope of relief.

"Basically we're trying to gear up for the recovery phase — not a sandbagging thing as much as rebuilding roads and infrastructure," Lambert said.

The Virgin, Santa Clara and San Juan rivers were all likely to continue running high in southern Utah before receding Wednesday. Rain in the area was likely to change to snow sometime Wednesday, National Weather Service hydrologist Brian McInerey said.

At least one death has been linked to the floods. A man driving near Quail Creek Reservoir climbed onto the roof of his SUV Monday after getting trapped in a flooded wash. He was swept away, and his body hasn't been found. No other injuries have been reported.

Washington County remained under a state of emergency, and officials were sending assistance, including about 50,000 sandbags.

Northern Utah did not escape trouble. More than a dozen homes in Pleasant Grove in Utah County were flooded Monday when storm drains spilled over.

In Logan, where nearly 20 inches of snow had accumulated since Saturday, some residents had spotty electrical service after wet, heavy snow took out tree branches and downed some power lines. A Smith's grocery store was evacuated after its roof bowed under the weight of heavy snow.

The storm also continued to dump heavy snow on Utah's mountain ranges and shut down the Alta ski resort Tuesday because of avalanche danger. Alta said it has gotten 9 feet of snow since Dec. 27.