UPDATE 4-Missouri towns brace for more flooding as Nebraska cleans up

(Adds town being evacuated, Army Corps briefing)

VALLEY, Neb., March 20 (Reuters) - Small Missouri towns on Wednesday prepared for the next wave of flooding along the snow-melt-swollen Missouri River after high waters wreaked nearly $1.5 billion in damage in Nebraska, and officials warned the deadly disaster was far from over.

Flood waters spawned by last week's late-winter storm and warmer weather that swiftly melted snow this week inundated a large swath of Missouri, Nebraska and Iowa along the Missouri River, North America's longest river. States of emergency have been declared in all or parts of the three Midwestern farm states.

The Missouri River's next big flood crest was due to hit on Thursday at St. Joseph, Missouri, about 55 miles (89 km) north of Kansas City, Missouri, and Atchison, Kansas, a short distance downstream, said U.S. Army Corps of Engineers spokesman James Lowe.

Levees broke in an area of northwest Missouri on Wednesday, prompting the evacuation of the small community of Craig. Local real estate agent Jamie Barnes said everyone in Craig had time to get out before it was flooded, and water was now flowing south through farmland toward communities such as Forest City, Forbes and St Joseph.

"There's just water as far as the eye can see, from bluff to bluff. In some places its five miles, in some 15," Barnes said by phone.

Several other communities in that area of northwest Missouri have also been evacuated, the Army Corps of Engineers said at a briefing. "Much of the levee system remains compromised, and as of noon Wednesday there are more than 30 total breaches across the system," in the three states experiencing flooding, Lieutenant Colonel James Startzell, deputy commander of the U.S. Army Corps of Engineers Omaha District told the briefing.

The floods have killed four people in Nebraska and Iowa since the weekend, and officials warned the toll of physical damage would rise as receding waters revealed more devastated roadways, bridges and homes.

Iowa Governor Kim Reynolds said the snow melt and spring rains could create additional flooding in the weeks ahead because of damaged levees.

"Were in for the long haul. Were just getting started," the Des Moines Register quoted her as saying. Reynolds said she had seen unprecedented flooding in a tour of western Iowa this week that had revealed unprecedented flooding. It looked like an ocean."

"STOP! STOP! TURN AROUND!"

In Valley, Nebraska, outside Omaha, Pete Smock, 42, worked to clear deep mud surrounding his home and construction business.

"Devastation is everywhere. I haven't seen anything like this in my lifetime," Smock said. He had rented heavy equipment to fill deep holes cut by the floods with gravel and repair driveways leading to his office and garage.

Authorities said they had rescued nearly 300 people in Nebraska alone.

More than 2,400 Nebraska homes and businesses were destroyed or damaged, with 200 miles (322 km) of roads unusable and 11 bridges wiped out, Governor Pete Ricketts told a news conference on Wednesday.

Ricketts estimated the floods caused at least $439 million in damage to public infrastructure and other assets, and $85 million to privately owned assets. He put flood damage for the state's agricultural sector at nearly $1 billion.

Offutt Air Force Base near Omaha, which houses the U.S. Strategic Command, remained heavily flooded, though base officials said on Twitter the facility was still "mission-capable." The Strategic Command's mission includes defending against and responding to nuclear attacks.

"We're looking for it to recede by late tomorrow," Drew Nystrom, a spokesman for the base, said on Wednesday. "It's gonna take a concentrated effort and many months to get everything back to normal."

In northwestern Missouri, farmer Howard Geib, 54, had a close call.

"I was driving out to get one more load of corn from the bins when the levee broke, and there was a wall of water coming at me," said Geib, 54, whose farm is near the town of Craig. "I was on the phone with my son-in-law, who was driving out to help, telling him, 'Stop! Stop! Turn around!'"

The flooding killed livestock, destroyed grains in storage and cut off access to farms because of road and rail damage.

Across the Missouri from the evacuated town of Craig, the village of Rulo, Nebraska, drew a small crowd of onlookers to see the deluge, said Kelly Klepper, owner of Wild Bills Bar & Grill.

"We're kind of a tourist attraction right now," Klepper said by phone. "People that don't normally come to Rulo have been coming to Rulo to check out the water."

(Reporting by Humeyra Pamuk; Additional reporting by Gina Cherelus in New York, Rich McKay in Atlanta, Jarrett Renshaw in Philadelphia, P.J. Huffstutter and Mark Weinraub in Chicago, and Dan Whitcomb in Los Angeles Editing by Bill Tarrant and Leslie Adler)