What are the health risks for those living near a cattle feedlot of about 18000 cows?

There are no more health risks living near a feedlot than living anywhere else in the farming community, except that you might not get used to the smell of the facility when the wind is blowing the smells your way. However, water contamination may be a problem if the feedlot doesn't have good manure management practices, but the water problem in itself is rare.