More than 1 million acres (405,000 hectares) of Arkansas farmland is under water as floods caused damage that the state expects will top $500 million, with losses heaviest in rice-growing areas.

About 300,000 acres, and about $300 million of the losses, are in rice, the Arkansas Farm Bureau Federation said in a statement on its website. In Missouri, at least 130,000 acres were flooded and another 900,000 acres are threatened by the cresting Mississippi River. In Louisiana, the state estimates  3 million acres may be inundated, much of it not in farms.

Damage estimates for Arkansas, the biggest rice-growing state, don’t include costs to repair farmland, equipment or lost crops. Those losses could add tens of millions of dollars, the Farm Bureau said. Farmers were expected to plant 1.3 million acres of rice this year, the organization said. Cotton losses may be $66 million, it said.

Flooding along the Mississippi River has caused damage from Illinois to Louisiana and disrupted inland shipping of raw materials to export terminals in the Gulf of Mexico. The river drains 41 percent of the continental U.S. and is the third- largest watershed in the world.