Impact of CAFOs on Water Quality
The public health risks posed by water polluted by livestock manure are essentially the same as those posed by human sewage. Many of the same chemicals and biological organisms that pose health risks from exposure to untreated human sewage also pose risks to human health from exposure to raw untreated hog sewage.
Raw untreated hog sewage generates over 150 gases, many of which are harmful, including ammonia and hydrogen sulfide, plus another 150 toxins. The animal waste from 2,500 hogs in a confinement feeding operation, the minimum size to be classified as a CAFO, is equivalent to the human waste from a municipality of 8,000 to 10,000 people.
There are logical reasons for requiring sophisticated, multi-stage waste treatment systems whenever 8,000 to 10,000 people choose to residence in close proximity and form a municipality. These same reasons raise legitimate public concerns when the feces and urine from 2,500 hogs is being stored and spread untreated on farmland. The chemical and biological wastes can seep into groundwater to pollute the wells of rural residents and can run off fields into streams that provide drinking water for municipalities on their way to oceans. A class I CAFO of 17,500 hogs produces as much raw sewage as a city of 55,000 to 70,000 people.
Defenders of factory farms claim that operators of CAFOs are responsible stewards of the environment. They extoll the virtues of traditional independent family farmers in their commitment to caring for the land and caring about the well-being of their neighbors. Even if this is true, it is simply not possible to manage the concentration of manure associated with large-scale confinement animal feeding operations without sophisticated waste treatment facilities. Furthermore, under the contractual agreements typical of CAFOs, the corporate contractor [definition], not the contract producer [definition], dictates the size and construction of production facilities that place an unmanageable manure disposal burden on the contract producer.
As a last defense, CAFO operators claim they are doing a better job of manure management than the traditional independent farmers they replaced. However, water quality statistics tell a different story. In 1998 the EPA found 35,000 miles of streams in 22 states and ground water in 17 states that had been polluted by industrial livestock operations.
According to the Iowa Department of Natural Resources, there has been almost a three-fold increase in “impairments” of water bodies between 2002 and 2012, years when factory livestock operations were rapidly replacing independent family farms. 3 The evidence is clear; the spreading of raw sewage from factory farms is threating the quality of drinking water.
1) Carla Klein, “The Facts about CAFOs and Health Ordinances,” Sierra Club, Ozark Chapter, 2006,
2) U.S. Department of Agriculture Natural Resources Conservation Service and U.S. Environmental Protection Agency, “Unified National Strategy for Animal Feeding Operations,” draft, September 11, 1998, as quoted in CAFO: The Tradegy of Industrial Animal Factories, Myths, Dan Imhoff, editor, http://www.cafothebook.org/thebook_myths_6.htm
3) Iowa Department of Natural Resources, Iowa’s Section 303(d) Impaired Water Listings,
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