WRAPUP 2-Midwest floodwaters wash levees, weather improves

*Sandbagged barriers give way, others under pressure

*Rains abate for the weekend, flood fighters relieved

*Costs mount, Obama says infrastructure spending needed

By Carey Gillam

WINFIELD, Mo., June 28 (Reuters) - The cresting Mississippi River washed over more flood barriers on Saturday but drier weather fed hopes of relief as the worst Midwest floods in 15 years added to billion-dollar losses, global food inflation fears and the political temperature in a U.S. election year.

Thunderstorms this week that had added to a month-long deluge let up and drier, cooler weather was forecast for saturated areas of Iowa, Missouri and Illinois where thousands of residents have been evacuated and hundreds of thousands of acres of prime farmland swamped.

In Winfield, Missouri, a levee break on Friday sent a rush of muddy water across 3,000 acres (1,214 hectares) of surrounding fields and prompted frantic efforts to hold back more water from the town of about 800 people north of St. Louis.

But those efforts failed shortly before dawn on Saturday as the river pushed through a six-foot- (1.8-metre-)high barrier of sandbags that stretched 2,000 feet (600 metres) along the community's eastern edge.

"The water won," said Lincoln County emergency management spokesman Andy Binder.

The water was rising rapidly on Saturday through the area of about 100 homes, playgrounds and ballparks.

"It just came in under the barrier and then blew through it," said Winfield Mayor Harry Stonebraker. "It's terrible ... what the Mississippi can do."

"I was hoping it would hold," said a weary Mary Navarro, whose gray two-bedroom home was one of the first to succumb to the floodwaters on Saturday. "I'm going to miss that house."

Binder said the flooding was now expected to swamp between 50,000 acres and 70,000 acres (20,240 hectares and 28,330 hectares) in the county, with the river 13 feet (4 metres) above flood stage. But the river crested at Winfield overnight at 37.1 feet (11.3 metres) and water levels were falling.

RECORD CORN PRICES

The Midwest storms and torrential rains have killed at least 24 people since late May. More than 38,000 people have been driven from their homes, mostly in Iowa where 83 of 99 counties have been declared disaster areas.

Fears that as many as 5 million acres (2 million hectares) of corn and soybeans have been lost to flooding in the world's largest grain and food exporter pushed corn and livestock prices to record highs in the last week.

Corn prices at the Chicago Board of Trade on Friday traded at a record $8.25 per bushel, more than double the 40-year average. Stockpiles of corn in the United States -- which normally ships more than half of all world corn exports -- had already been projected at 13-year lows next year.

So the effect on global food prices as U.S. prices soar has alarmed everyone from central bankers to food aid groups.

Flood aid and relief was heating up as a political issue.

Democratic Party presidential candidate Barack Obama said on Saturday that the Midwest levee breaks and damage to bridges, highways, locks and other decades-old structures were reasons to back his $60 billion spending proposal to modernize U.S. roads, bridges and waterways for competitiveness and jobs.

"We're falling behind," Obama told RadioIowa in a phone interview. "A 500-year flood, perhaps much of this damage could not have been prevented even if our infrastructure was top notch. But some of it could have been, and recovery could have proceeded more quickly."

Iowa Gov. Chet Culver said on Friday 45,000 square miles (116,500 sq km) of the state had been hit by tornadoes or flooding, including 340 towns, with extensive damage to road and rail lines at a cost of "tens of billions of dollars."

WEATHER COOPERATING

U.S. Army Corps of Engineers St. Louis District spokesman Alan Dooley said the strained situation with flood barriers on the river looked less dire downstream around St. Louis, where more sophisticated levee systems were in place.

"We have a high level of confidence ... that they will be well able to fend this off," Dooley said. "Downriver, you're looking at the crest still to arrive."

The Corps was forecasting that the river would crest again at St Louis on Monday at 38.7 feet, compared to the record 49.9 feet in the last major flood in 1993. At Cape Girardeau, 100 miles south of St Louis, the crest was expected on July 2 at 43 feet, compared to the record of 47.9 feet in 1993.

Dooley said those crests looked manageable with existing levees and flood control systems, but he added: "If we don't have any more rain."

The National Weather Service on Saturday said scattered thunderstorms were possible in a few parts of the southern and eastern Midwest through the weekend, but the areas worst-hit by torrential rains and floods this month looked to be dry.

Chemicals from farm fields and other toxic substances left behind as waters recede have created a potential health threat. Damaged municipal sewage systems in places like Cedar Rapids, Iowa, were releasing raw sewage into rivers. But drinking water supplies remain unpolluted in most areas, officials said. (Additional reporting by Kay Henderson in Des Moines; Writing by Peter Bohan; Editing by Eric Walsh)