In a sight more common in river towns and the Gulf states, people filled sand bags in downtown Casper on Saturday afternoon to deter anticipated flood waters from further damaging the basement of the Hall of Justice.

Natrona County Commission Chairman Rob Hendry shoveled sand, tied the strings, and placed the white bags at the top of the ramp descending to the garage at 201 N. David St.

The sand-baggers didn't want any more rain - projected for Saturday evening - to wash into the garage after flood waters caved in the overhead door, Hendry said. "The water ruined the door to the garage."

The city and county share the building for the sheriff's office, police department, juvenile detention center, the district attorney, and circuit court.

The rain filled the shafts for the recently replaced elevators, damaging the shaft bearings and electric lines; and it collapsed the ceilings of the offices of the sheriff, undersheriff and their assistants, he said.

While Casper and Natrona County have cash reserves, they hope they can draw on insurance through the Wyoming Association of Risk Management and funds for public emergencies, he said.

Earlier Saturday, Hendry and Casper Mayor Kenyne Schlager signed letters addressed to Gov. Dave Freudenthal that declared a county-wide disaster with requests for assistance.

They each estimated the storm caused $2 million in infrastructure to their respective governments.

Some damage estimates were preliminary, such as about $350,000 to the Wyoming Medical Center's basement, Hendry said. The county-owned hospital assets are leased by the nonprofit Wyoming Medical Center Inc.

The city, too, began to recover.

Rocks and dirt dropped by the fast currents littered and damaged streets, and Casper's public services director Gary Clough cautioned motorists to watch for debris and damaged pavement.

Because of the Fourth of July weekend, road crews were scarce, Clough said in a news release. "Full crews will be out Monday to begin cleaning the streets," he said. "Arterial and collector streets will be cleaned first, and we expect to have all streets cleaned by Thursday."

Over at the Nicolaysen Art Museum, curator Lisa Hatchadoorian and others spent about four hours Friday night sweeping out between one-half and one-and-a-half inches of water throughout the city-owned property managed by a nonprofit organization.

They were finishing their work on Saturday, but remained nervous about reports of another storm coming that evening.

The water covered the floors of the galleries, gift shop, lobby, loading dock, and preparation room, Hatchadoorian said.

In many respects, they were fortunate, she said. "None of the collection was damaged."

On the other hand, the water destroyed much of the contents of a storage room including about $30,000 worth of catalogues and crates, she said.

The damage could have been much worse, Hatchadoorian said.

The city recently replaced the roof that had leaked into the gallery, she said. "Instead of $30,000, it could have been a half-million."

Rare event

The whole experience could have been much worse.

No one died or was seriously injured , said Bob Fawcett of the Casper Fire-EMS Department.

Nor were there reports of downed power lines, which are deadly when mixed with rain and wet ground, Fawcett said.

The storm could have done all that and more.

In one of the letters to Freudenthal, Hendry and Schlager said the "suspected wet microburst" near the airport poured more than seven-tenths of an inch of rain in 12 minutes, or 3.5 inches per hour.

Downtown Casper received about 2.25 inches during the storm.

Wind speeds ranged from 47 mph at the airport to 63 mph at the hospital to 65 mph on Wyoming Boulevard, they said, citing the National Weather Service in Riverton and local sources.

"This event caused severe damage to public infrastructure and private property, disruption of utility services to include water and electricity outages, and endangerment of health and safety to the citizens of Natrona County within the damaged areas," they wrote.

Members of the Community Emergency Response Team, law enforcement and other officials had received more than 125 calls from residents and business owners by 3:30 p.m. Saturday at the command center called the "blue room" on the second floor of the Hall of Justice.

They expected those numbers - and the damage estimates - to rise, especially when people return from out-of-town holiday events today and Monday.

Even seasoned veterans of emergencies were amazed by the storm.

"I've been here 30 years, and I've not seen it," said Casper Fire Chief Mark Young. "I've never seen such flash flooding."

Reach Tom Morton at (307) 266-0592, or at tom.morton@trib.com. Read his blog at tribtown.trib.com/TomMorton/blog.

In pictures

See the pictures of the flash flooding from various points around Casper on Friday evening at the WyoWeather TribTown group located here: http://tribtown.trib.com/post/Groups/WyoWeather/blog/flash_flooding_in_casper.html. Now updated to include Star-Tribune photographer Kerry Huller's photos.