Groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

pollution, also referred to as groundwater contamination, is not as easily classified as surface water pollution. Groundwater

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

s are susceptible to contamination from sources that may not directly affect surface water bodies. Analysis of groundwater contamination may focus on soil characteristics and site geology,

hydrogeology Hydrogeology (''hydro-'' meaning water, and ''-geology'' meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquif ...

, hydrology, and the nature of the contaminants. Causes of groundwater pollution include: naturally-occurring (geogenic), on-site sanitation systems,

sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

s and

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...

, commercial and industrial leaks,

hydraulic fracturing Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...

, and landfill leachate. Groundwater contamination in

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

impacts many regions, such as the Central Valley. One of the sources of groundwater contamination can be linked to

animal agriculture Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, or other products. It includes day-to-day care, selective breeding, and the raising of livestock. Husbandry has a long history, startin ...

and Animal feed operations (AFO). These facilities tend to have a higher concentration of animal

manure Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nutri ...

, which when stored improperly can cause problems by leaking into local groundwater and aquifers, causing groundwater contamination. Under the

Clean Water Act The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibiliti ...

, AFOs are considered a point source of pollution and are held to specific standards by the United States'

Environmental Protection Agency (EPA) The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

Basic information

According to the EPA in a 2007 survey, 10% of California's groundwater has a

Nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

level greater than 5 mg/L. This equates to around 7% of the population that is drinking contaminated groundwater. Five mg/L is half of the EPA limit of allowed nitrogen in water. There are two primary sources of pollution for nitrogen: agriculture and septic systems.

Agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

can contribute from heavy use of fertilizer as well as animal agriculture waste. Over 68 published and peer-reviewed studies have been conducted since 2002, out of these studies 15 found direct links to groundwater pollution from animals' waste at CAFOs. Twelve of the studies made indirect links to

water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...

and

human health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...

while seven found no link at all

California ground water

Due to factory farming practices and the use of

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

-rich

s and animals waste in 1994 over 800 wells were closed in

southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

, 130 of those well in the San Joaquin Valley. A study conducted in 1996 by the University of California, in which they monitored and surveyed 5 dairies in a high- risk groundwater area, higher levels of nitrates and salts were present under main milking areas, wastewater retention ponds and other land use areas. According to the Central Valley Dairy Representative Monitoring Program, some practices that are now implemented may not be represented in this data as some provisions of the 2007 General Order was only fully enforced and complete in 2012, when monitoring began. Please See Central Valley groundwater pollution

Point source pollution

In the United States, there are roughly 450,000 concentrated animal feed operations (CAFO) where cows are held for at least 45 days over a 1-year period, in which a single cow can defecate up to 120 lb of manure a day, which is the equivalent of 20-40 people. Under the Clean Water Act Section 502(14) a CAFO is considered a point source of pollution.

Regulation under the EPA

With the federal law on the side of the EPA, EPA has the authority to specifically regulate CAFO's as a polluter. According to the Clean Water Act, CAFO's are considered like other polluting industry in which the business must acquire a permit to pollute and they must have several controls in place. CAFO's are defined under the EPA as three distinct sizes that are based on the number of animals housed are as follows: "A Large CAFO confines at least the number of animals described in the table below. A Medium CAFO falls within the size range in the table below and either: • has a

manmade Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...

ditch A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circula ...

that carries manure or wastewater to surface water; or • the animals come into contact with surface water that passes through the area where they’re confined. If an operation is found to be a significant contributor of pollutants, the permitting authority may designate a medium-sized facility as a CAFO. A Small CAFO confines fewer than the number of animals listed in the table and has been designated as a CAFO by the permitting authority as a significant contributor of pollutants. "

References

{{reflist ''attribution'':

Groundwater pollution Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted ...

for introduction Water in California Water pollution in the United States

Basic information

California ground water

Point source pollution

Regulation under the EPA

See also

References