WRAPUP 4-Worst seen over for Midwest floods, cleanup starts

* Mississippi River crests at St Louis, high water lingers

* Mostly fair weather gives tired flood fighters a break

* Returning residents face a toxic mix on flood plain

By James B. Kelleher

EAST ST. LOUIS, Ill., June 21 (Reuters) - The worst Midwest flooding in 15 years eased on Saturday after the swollen Mississippi River crested in St. Louis, but the toll was still rising as billions of dollars in damage to crops, communities and infrastructure were assessed.

Emergency workers at river levees and floodwalls feared more rain could swell river levels again and complicate recovery efforts. But the skies remained mostly clear and thousands of relief workers could finally exhale.

"It really is looking positive. The weather has cooperated and that's made a difference," said Maggie Carson, a spokeswoman for Illinois Emergency Management in Alton, Illinois, a few miles north of St. Louis.

Thunderstorms seen for the northern Midwest in the next few days were expected to be scattered and pose no new threat.

The flooding and storms blamed for 24 deaths since late May have caused billions of dollars in damage to the heart of the U.S. grain belt, pushing corn and other food commodity prices to record highs and feeding fears of higher world food prices.

Bridges and highways have been swamped, factories shut down, water and power utilities damaged, and the earnings of railroads, farmers and myriad other businesses disrupted.

Iowa and Illinois have been the hardest hit, but parts of Wisconsin, Minnesota, Indiana and Missouri have also been swamped. The runoff from torrential rains in the northern Midwest in late May and early June fed the Mississippi's southward torrent.

As the Missisippi crested, towns along the river's vast flood plain were left to tally their losses and wait for the waters to subside, which could take weeks or even months.

"Right now things are looking good. The crisis part is passed and that's heartening. We're breathing a sigh of relief," said Farm Bureau official Blake Roderick, executive director for Pike and Scott counties in Illinois.

'ST. LOUIS HAS CRESTED'

River levels peaked in St. Louis at 37.27 feet (11.3 metres) late on Friday, lower than earlier forecast and well below the record of 49.58 feet (15.1 meters) set in 1993.

More than two dozen levee breaks up-river earlier in the week took pressure off downstream areas.