There is the undeniable stink of racism about the ads. One ad blamed immigrants for reducing the quality of life in Storm Lake, implying that any city with a big non-white population is doomed. Maybe the quality of life has declined in Storm Lake, I don't know. That doesn't mean it's the immigrants' fault. The Storm Lake police chief says crime increases have nothing to do with its immigrants but on other factors that arose at the same time.
Immigrants are just easy to blame.
They may look different, so they stand out in an all-white town. Blaming immigrants for social ills is picking a scapegoat. Immigrants do stretch resources. Because they enter the economy at the bottom rung, they have welfare needs. Teaching students who don't understand English is an additional cost to the school system.