This can lead to widespread pollution within the watershed that the CAFO is located within, if the water from these lagoons leaches out into the soil and trickles down into the water table beneath. Unlike human sewage, which is always treated with chemical and mechanical filtration, the waste from these lagoons is untreated when it is released back to the environment. Spills are the most common contributor to pollution, but regardless of spills, toxic nutrients like nitrates and ammonia can seep into the water table located just below the surface, infecting the groundwater that nearby communities drink. It has been estimated that 35,000 miles of river across over 20 states has been contaminated by manure leakage. Some of the causes for the environmental problems are inadequate sewage treatment and lack of developing technologies. Many farms lack adequate wastewater treatment systems, which release untreated wastewater to release into the environment in the form of contamination. Some spills and leakage of contaminated waste are not accidental. In 2014, Mark Devries used spy drones to expose pig farms in North Carolina that were spraying untreated fecal waste into the surrounding areas, allowing the waste to dissipate into far-off communities. Smithfield Foods, the company responsible for one such factory, claimed this was a tactic used to fertilize its fields. It is true that historically hog feces have been used as fertilizer and can be done safely and without runoff, but the magnitude was described by Dan Whittle, a former senior policy associate at the North Carolina Department of Environment and Natural Resources, as a "mass imbalance", with far too great a magnitude of fecal matter being sprayed for the crops being generated to not have significant spill off into neighboring plots of land. Many residents of the surrounding areas of such farms complain that the industrially concentrated fecal matter creates an unbearable odor of a different magnitude than typical farm manure. Charlotte Savage, a resident who lives on a property separated from the Smithfield farm by an 80-foot path of forest, reported seeing her husband Julian faint at one point due to the smell, and that their house was also once surrounded by a three foot deep puddle of fecal matter. This was described as a common occurrence in this community and many others. Communities located near CAFOs experience negative health and environmental effects due to several factors associated with industrial pig farming. One main issue that arises out of intensive animal agriculture is the waste that the huge number of animals in a small space produce. In the pig farming industry, there are huge amounts of waste and farmers are pressed to find somewhere to put it and dispose of it.