( CNN ) -- The flood damage to Iowa crops could reach $ 3 billion , according to the state 's agriculture secretary . Three pigs stand stranded on the roof of a building Friday in Oakville , Iowa . `` Right now , we have about 10 percent of our corn that has either been flooded out or not planted and about 20 percent of our [ soy ] beans , '' Bill Northey said Friday on `` Iowa Press , '' a public television show . `` We 're seeing some beans go back in the ground , and if we were to lose that , if we were n't able to replant , that would be $ 2.5 billion , $ 3 billion -- a significant amount of damage , '' he said . He added that some of the remaining crops would probably have smaller yields . Flooding in several Midwestern states has killed two dozen people and injured 148 , according to the Federal Emergency Management Agency , and 35,000 to 40,000 people in several states have been displaced . Watch an iReporter 's chronicle of the floods » . `` I think some of this was absolutely uncontrollable , '' Northey said . `` If you are ready for every potential event that could happen once out of every hundred years or 500 years , you 're probably not going to be able to be in business and make it on a normal year . So , some of this is just flat-out unpredictable , '' he said . In Iowa , where several rivers jumped their banks about a week ago , water covered city blocks , ruined homes and poured over acres of farmland . This week , residents are returning to homes , and officials are assessing damage as the floodwater moves downstream to add to the Mississippi River 's flow . Despite the acres of flooded farmland in Iowa , `` there certainly are folks out there with good crops , '' Northey said . `` There 's areas with good crops , and within all areas , there 's folks with good crops and poor crops , '' he said . Flooding of some of the food processing facilities in Iowa also has a `` very significant '' impact on Iowa 's agriculture , Northey said . `` We 're just starting to hear some of those things , just starting to figure out . Those change markets , and in many cases those losses , if they are by flooding , in some cases those are not covered by insurance , '' he said . On Thursday , President Bush toured the flood-ravaged state by air . `` Obviously , to the extent that we can help immediately we want to help , and then plan for recovery , '' the president said at Kirkwood Community College in Cedar Rapids , Iowa . `` You 're exhausted ; I understand that , '' he said . `` The good news is , the people in Iowa are tough-minded people . You 'll come back better , '' he said . Iowa Gov . Chet Culver , who toured the area with Bush , said , `` we will rebuild this state and this city , and it will be even better and even stronger as a result . ''
Agriculture secretary estimates 10 percent of corn , 20 percent of soybeans lost . Remaining plantings could show reduced yields , official says . Some agricultural losses will not be covered by insurance . President Bush tours flooded area by air , promises help .