In animal farming, a concentrated animal feeding operation (CAFO), as defined by the United States Department of Agriculture (USDA), is a type of intensive animal feeding operation (AFO) where more than 1,000 animal units are kept in confinement for more than 45 days each year. An animal unit equals 1,000 pounds of live animal weight. For example, 1,000 animal units could be 700 dairy cows, 1,000 meat cows, 2,500 pigs weighing more than 55 pounds, 10,000 pigs weighing less than 55 pounds, 10,000 sheep, 55,000 turkeys, 125,000 chickens, or 82,000 egg-laying hens or pullets.
CAFOs follow rules that control how much animal waste can be spread and the quality of the waste materials. In 2012, there were about 212,000 AFOs in the United States, with 19,496 of them being CAFOs.
Livestock farming in the United States and other countries has become more focused on CAFOs. Most poultry was raised in CAFOs starting in the 1950s, and most cattle and pigs by the 1970s and 1980s. By the mid-2000s, CAFOs were the main way to raise livestock and poultry in the United States, and their share of the market has continued to grow. In 1966, it took 1 million farms to raise 57 million pigs; by 2001, the same number of pigs was raised on only 80,000 farms.
Definition
There are about 212,000 AFOs in the United States, and 19,496 of them met stricter standards to be classified as CAFOs in 2016. The Environmental Protection Agency (EPA) has defined three categories of CAFOs based on their size: large, medium, and small. The number of animals required for each category depends on the type of animal and the size of the operation. For example, large CAFOs have 1,000 or more cattle, medium CAFOs have between 300 and 999 cattle, and small CAFOs have 300 or fewer cattle.
The table below shows examples of the size limits for CAFOs:
The classification of CAFOs determines whether a facility must follow rules under the Clean Water Act (CWA). According to the EPA's 2008 rule, large CAFOs automatically must follow EPA regulations. Medium CAFOs must also meet one of two "method of discharge" requirements to be classified as CAFOs (or may be designated as such). Small CAFOs are only subject to EPA regulations in specific cases. A small CAFO will also be classified as a CAFO under the CWA if it releases waste into U.S. waterways through man-made paths like roads, ditches, or pipes. Alternatively, a small CAFO may be classified as an ordinary AFO if its animal waste management system is certified on-site.
Since the term was first introduced, the EPA has updated the definition and related rules for CAFOs multiple times. Private groups and individuals often use the term CAFO in everyday language to describe various types of facilities, both regulated and unregulated, inside and outside the United States. This common use of the term may differ significantly from the official legal definition in the CWA. CAFOs are often described as facilities where many animals are kept in a confined area, leading to the concentration of manure in a small space.
Key issues
The Environmental Protection Agency (EPA) has focused on regulating Concentrated Animal Feeding Operations (CAFOs) because they produce millions of tons of manure each year. If not managed properly, this manure can harm the environment and public health. To handle their waste, CAFO operators create plans for treating agricultural wastewater. One common method is using anaerobic lagoons, which have caused environmental and health problems linked to CAFOs.
Large amounts of animal waste from CAFOs can damage water quality and harm aquatic ecosystems. States with many CAFOs often face 20 to 30 serious water quality issues each year due to poor manure management.
Animal waste contains harmful pollutants, including:
1. nitrogen and phosphorus, which cause nutrient pollution;
2. organic matter;
3. solids like manure, spilled feed, bedding, hair, feathers, and animal remains;
4. pathogens such as bacteria and viruses;
5. salts;
6. trace elements like arsenic;
7. odorous compounds such as carbon dioxide, methane, hydrogen sulfide, and ammonia;
8. antibiotics;
9. pesticides and hormones.
The main causes of water pollution from CAFOs are soluble nitrogen and phosphorus. These substances can lead to eutrophication, which harms wildlife and water quality in streams, lakes, and oceans.
Groundwater and surface water are connected, so pollution in one can affect the other. Surface water may become polluted when nutrients, organic matter, and pathogens from fields or storage areas run off into waterways. Waste can also pollute groundwater through the leaching of pollutants. Some designs, like lagoons, may reduce groundwater risks, but pathogens from animal waste can still harm surface and groundwater, affecting wildlife and human health.
A CAFO was responsible for one of the largest environmental spills in U.S. history. In 1995, a lagoon in North Carolina, which was 120,000 square feet (11,000 m²), broke and released 25.8 million gallons (98,000 m³) of waste into the New River. This spill killed 10 million fish and contributed to an outbreak of Pfiesteria piscicida, which caused health issues in nearby humans, such as skin irritation and short-term memory problems. North Carolina has many industrial hog operations, which disproportionately affect Black, Hispanic, and Native American communities.
CAFOs reduce air quality by releasing harmful gases like ammonia, hydrogen sulfide, methane, and particulate matter. Larger CAFOs produce more gas, mainly from the breakdown of animal manure. They also emit antibiotic-resistant bacteria into the air, especially downwind. Studies show antibiotic levels downwind from swine CAFOs are three times higher than upwind. The source of these antibiotics is not fully understood, but animal feed is suspected.
Globally, ruminant livestock contribute about 115 teragrams (Tg) per year of the 330 Tg (35%) of human-caused greenhouse gas emissions. Livestock operations account for about 18% of global greenhouse gas emissions and over 7% in the U.S. Methane is the second most common greenhouse gas, with livestock responsible for nearly 30% of human-caused methane emissions. Only 17% of livestock-related emissions come from manure; most come from digestion processes. About 76% of bacteria found in swine CAFOs are Staphylococcus Aureus, followed by Group A Streptococci and Fecal Coliforms.
The Intergovernmental Panel on Climate Change (IPCC) recognizes the significant role of livestock in methane emissions, antibiotic resistance, and climate change. To reduce emissions, it suggests removing stressors and changing animal diets, including feed grain sources, forage amounts, and nutrient levels. The Humane Society of the United States (HSUS) supports reducing non-therapeutic antibiotics, especially those used in human medicine, as advised by over 350 organizations, including the American Medical Association. If methane emissions continue to rise with the number of livestock, global methane production could increase by 60% by 2030. Greenhouse gases and climate change worsen air quality, causing illnesses like respiratory problems, lung damage, and allergies. Reducing emissions from livestock could help slow global warming. People near CAFOs often complain about strong odors from a mix of ammonia, hydrogen sulfide, carbon dioxide, and volatile organic compounds.
Waste disposal from CAFOs also harms air quality. Some CAFOs use "spray fields" to spread waste onto open fields. This waste can be carried by wind to nearby homes, releasing pathogens, heavy metals, and antibiotic-resistant bacteria into the air of poor or minority communities. It often contains irritants like hydrogen sulfide and ammonia.
CAFOs have grown significantly in the U.S. over the past decades and now dominate animal production industries. Large-scale animal agriculture began in the 1930s with modern mechanization of swine slaughterhouses. The rise of corporate contracts has shifted from many small farms to fewer large industrial farms, changing the U.S. agricultural sector. According to the National Agricultural Statistics Service, there were about 7 million farms in the U.S. in the 1930s, but by 2002, only about 2 million remained. From 1969 to 2002, the number of family farms dropped by 39%, though most U.S. farms are still family-owned. Most meat and dairy products are now produced on large farms with single-species buildings or open-air pens.
CAFOs provide low-cost animal products like meat, milk, and eggs due to their efficiency. They may also boost local economies through jobs and the use of local materials. Advances in animal breeding, technology, and specially formulated feeds have reduced the cost of animal products for consumers. New technologies have also helped CAFOs cut production costs and increase profits with fewer resources. The growth of CAFOs has led to increased consumption of animal products in the U.S. According to Christopher L. Delgado, milk production has doubled, meat production has tripled, and egg production has quadrupled since 1960.
Despite these benefits, CAFOs face criticism for economic impacts. Many U.S. farmers struggle to earn high incomes due to low market prices for animal products. These factors often lead to low profits and competition against CAFOs.
Regulation under the Clean Water Act
The Clean Water Act (CWA) sets the rules for managing pollution from Concentrated Animal Feeding Operations (CAFOs) in the United States. Under the CWA, it is illegal to release pollution into "waters of the United States" from a "point source" unless a permit is obtained from the Environmental Protection Agency (EPA) or a state approved by the EPA. A "point source" is a specific place where pollution comes from, such as a pipe or ditch. CAFOs are listed as point sources in the CWA. If CAFOs release pollution without a permit, even if the release is accidental, they break the law. CAFOs that do not apply for a permit risk being punished, including legal action by citizens or government agencies.
Getting an NPDES permit gives CAFO owners and operators some protection. If they follow the permit rules, they are considered to be following the CWA, which helps them avoid legal problems. Permits also include rules for emergencies, like natural disasters, that might cause unexpected pollution. These rules can help CAFOs defend themselves legally if such events happen.
The EPA sets limits on how much pollution can be released by facilities in certain industries, like CAFOs. These limits, called "effluent limitations guidelines" (ELGs), guide the specific rules in NPDES permits. The limits are based on the best technology available, but the EPA does not require industries to use that technology. Instead, industries can use other methods to meet the pollution limits.
Each NPDES permit for CAFOs must include minimum requirements set by the EPA. These requirements can include numbers that show how much pollution can be released and other rules, such as how to manage waste or use certain technologies.
Major changes to CAFO rules happened in the 1970s and 2000s. In 1976, the EPA created ELGs for CAFOs. In 2003, the EPA updated these rules, but a court later said some parts of the 2003 rule were not correct. The EPA fixed the rules in 2008.
A full list of EPA actions related to CAFOs is available on the CAFO Rule History page.
The Federal Water Pollution Control Act of 1948 was the first major U.S. law to address water pollution. It aimed to improve water quality for fish, industry, and recreation. The law has been changed many times since 1948 to improve rules and standards.
In 1970, President Richard Nixon created the EPA through an executive order. The EPA was formed to manage pollution more effectively. Nixon said a single agency should handle all types of pollution, including air, water, and land. The EPA became the main federal group responsible for regulating CAFO pollution.
The CWA was passed in 1972. It reworked the 1948 law and defined CAFOs as point sources of pollution. It required CAFO owners to get NPDES permits to legally release wastewater.
After the CWA passed, the EPA started regulating CAFOs. In 1974, the EPA created rules for feedlot operations based on the best technology available at the time. In 1976, the EPA required all CAFOs to first be classified as AFOs. If an AFO met certain conditions, it would be called a CAFO and regulated. That year, the EPA also created rules for livestock and poultry CAFOs and set up a special permitting program for NPDES permits.
Before 1976, CAFOs were mainly defined by size. After 1976, the EPA added exceptions. Some operations could be called CAFOs even if they were smaller, if they caused serious harm to waterways. Some CAFOs did not need permits if they met two conditions: releasing wastewater only during a rare 25-year storm or applying animal waste to farmland.
In 1989, the Natural Resources Defense Council and Public Citizen sued the EPA for not following the CWA. The court ordered the EPA to update its rules, leading to the 2003 Final Rule.
In 1995, the EPA released a guide to help the public understand NPDES rules after confusion about CAFO regulations. The guide was not a rule but explained previous rules.
In 1998, President Bill Clinton asked the USDA and EPA to work together to improve water quality standards. They held public meetings to discuss AFOs and released a framework called the Unified National Strategy for Animal Feeding Operations in 1999. The framework included six steps for managing waste and two types of programs: voluntary programs and regulatory programs with NPDES permits.
In 2003, the EPA updated old rules to reflect new technology and improve pollution control. This was partly because of a court order from 1991.
States' role and authority
The federal government sets national rules for environmental issues, while state governments handle specific problems. Federal rules require states to prevent, reduce, and stop pollution.
Water and air standards are managed through this system. States approved by the EPA can issue permits under NPDES (also called "NPDES states"). These states have control over CAFOs. Because of this, CAFO permit rules and standards may differ between states.
For water pollution, the federal government sets rules for wastewater discharge. Approved states create their own rules that must be as strict or stricter than federal standards. These rules apply to all waterways, even if they are not safe for aquatic life or public use. Some waterways, like parks, have higher standards to protect the environment. Lower standards may be allowed in certain areas if it is economically important. These rules show how state governments manage CAFO permits.
Federal law requires CAFOs to get NPDES permits before discharging wastewater. The state agency that approves these permits depends on whether the state is authorized. The permit process has two main methods based on a state’s authorization. As of 2018, 47 states are authorized to issue NPDES permits. Their rules must meet or exceed federal standards. In other states and territories, the EPA issues permits directly.
A state’s authority and environmental rules determine the permit process and which offices are involved. Here are two examples:
In Arizona, permits are issued through a general process. CAFOs must get both an Arizona Pollutant Discharge Elimination System (AZPDES) Permit and an Aquifer Protection Permit. The Arizona Department of Environmental Quality (ADEQ) manages this process.
For the Aquifer Protection Permit, CAFOs are automatically approved if they follow state Best Management Practices (BMPs) listed on ADEQ’s website. Compliance is checked through inspections. If a facility illegally discharges waste, ADEQ may issue warnings or take legal action. For the AZPDES permit, CAFOs must submit a Notice of Intent to ADEQ and complete a Nutrient Management Plan (NMP) for the state’s annual report.
Even in authorized states, the EPA oversees state programs. This might happen if a third party files a complaint. For example, in 2008, Illinois Citizens for Clean Air & Water complained to the EPA about Illinois’ CAFO permitting program. The EPA conducted an informal investigation and found the state needed to improve its program.
In unauthorized states, the EPA issues NPDES permits. For example, in Massachusetts, CAFOs work with the EPA regional office. The state’s Department of Agricultural Resources (MDAR) helps operators determine if their facility is a CAFO. MDAR provides advice and technical support but does not issue permits.
If a state has its own water quality rules, it manages permits. For example, New Mexico, an unauthorized state, requires CAFOs to get a Groundwater Permit if waste might affect local groundwater. The EPA does not issue this permit. Massachusetts does not have additional permit requirements.
Zoning ordinances
State planning laws and local zoning rules are the main tools used to control how land is used. Many states have created laws that allow Concentrated Animal Feeding Operations (CAFOs) and other farming businesses to avoid following zoning rules. Some states have passed "right to farm" laws, which help protect farmers and other agricultural businesses from being held responsible for problems they may cause. These laws aim to reduce the situations in which farming activities are considered a nuisance.
The idea of giving farming operations special treatment began in the 1950s. In the 1970s, more states added "right to farm" laws to protect farmland from being taken over by cities. At that time, lawmakers did not consider CAFOs or modern farming methods as the main benefiters of these laws. Today, 43 states have laws that protect farmers from being sued for nuisances. Some states, like Iowa, Oklahoma, Wyoming, Tennessee, and Kansas, also protect animal feeding operations (AFOs) and CAFOs specifically. These laws vary by state. For example, some states require farming operations to be in areas officially approved for farming to receive protection, while others do not.
People who oppose CAFOs have taken "right to farm" laws to court, and it is still unclear if these laws are legal. In 1998, the Iowa Supreme Court ruled that one of these laws was unconstitutional because it took away property rights from nearby landowners without paying them.
As of February 2023, 85 counties in Iowa, which is most of the state, passed a "Construction Evaluation Resolution." According to Iowa law, only counties that adopt this resolution can send recommendations to the Iowa Department of Natural Resources about whether to approve or reject construction permits for new CAFOs. These recommendations apply to permits received between February 1, 2023, and January 31, 2024.
Regulation under the Clean Air Act
CAFOs may be subject to rules under the Clean Air Act (CAA), but their emissions usually do not go over limits set by law. Also, the EPA's rules do not clearly explain how to measure emissions from CAFOs, which has caused problems for both regulators and the farming industry. In 2005, the EPA and agricultural groups reached an agreement called the Air Compliance Agreement. Under this agreement, some animal feeding operations (AFOs) agreed not to be sued by the EPA in exchange for paying a fine for past CAA violations and allowing their facilities to be studied for air pollution emissions. Results from the EPA's study are expected to be shared in 2011.
Environmental groups have asked the EPA to strengthen rules on air pollution from CAFOs. A group of environmental organizations requested on April 6, 2011, that the EPA classify ammonia as a "criteria pollutant" and create National Ambient Air Quality Standards (NAAQS) for ammonia from CAFOs. The request states that "CAFOs are major sources of ammonia in the United States; one EPA estimate shows livestock produce about 80% of total ammonia emissions. CAFOs also release a large amount of ammonia in some states and communities." If the EPA agrees to the request, CAFOs and other ammonia sources would need to follow the CAA's rules for permits.