With the nitrogen and phosphorous that comes from it, what really frightens me is the specter of pathogens," former chief of runoff management for the Wisconsin DNR said. "With more and more of this untreated liquid manure we're putting rural populations at health risks." Depending on its size, a single CAFO can produce the same amount of waste as a town or small city with none of the waste treatment requirements of a municipality, several sources explained. CAFOs are only required by the DNR to have the requisite amount of land to spread their large amounts of manure.