Share this: Pigs are raised at a hog operation in Hawarden, Iowa. Lawmakers in Iowa and a handful of other states, frustrated by agricultural regulations they say don’t adequately protect water and air quality, have filed legislation to ban new or expanded large-scale farms. (Nati Harnik The Associated Press) Iowa has a poop problem. The Hawkeye State’s pigs, cows and chickens produce about as much waste as 134 million people—nearly the population of Russia. Most of that manure is spread onto fields as fertilizer, where significant amounts of it wash into Iowa waterways. The city of Des Moines uses one of the most expensive nitrate removal systems in the world to make its water supply from the Raccoon River safe to drink.