 Industrial
agriculture is one of the leading causes of water pollution in
the United States today. In the 2000 National Water Quality
Inventory conducted by the Environmental Protection Agency
(EPA), agricultural activity was identified as a source of
pollution for 48% of stream and river water, i and
for 41% of lake water.ii
 Water
pollution from industrial farms not only damages the environment
and kills wildlife, but it can also sicken and kill people. And
since these farms exercise little restraint when it comes to
water usage, they tend to waste large quantities of water, even
when neighboring communities are experiencing water
shortages. Because small, sustainable farms are more
integrated with their surrounding communities, they pay closer
attention to the ways that they use water and how their
practices affect local water supplies.
Sources of Pollutants
Most water pollution from industrial farms results from the
storage and disposal of animal waste.
Industrial livestock farms store manure and other farm wastes in
gigantic tanks known as “lagoons” which can hold
millions of gallons of manure and urine. Unfortunately, these
lagoons often leak and—during large storms—they may
rupture or simply overflow. When this happens, the environmental
damage can be devastating, as raw manure is up to 160 times more
toxic than raw municipal sewage.iii Leaking lagoons
also release antibiotic residues
and harmful bacteria that can leach into water supplies.
In order to dispose of manure after it’s been
stored in lagoons, industrial farms spray the waste onto farm
fields as fertilizer. Unfortunately, these farms produce far
more waste than can be applied to fields, and once the
saturation point has been reached, the waste runs off into
nearby water systems. The most common form of water
pollution in the United States is excess levels of nitrogen or
phosphorous, both of which are largely caused by fertilizer
runoff.iv When manure is spread on fields as a
fertilizer, it can also introduce some of the more toxic
substances present in livestock excretions, such as
pharmaceuticalsv or bacteria.vi Water
pollution from manure as well as synthetic fertilizers can lead
to serious environmental damage and harm human health.
Types and Effects of
Pollutants
Agricultural water pollution can have variety of negative
effects. Not only do substantial environmental problems
result, but many of the pollutants produced by farms (minerals,
chemicals and pathogens, to name a few) can make water unsafe
for human consumption.
Nutrients
Nutrients, such as nitrogen and phosphorous, are the minerals in
fertilizer that promote plant growth. But due to the
over-fertilization of cropland, far more nitrogen and
phosphorous are applied to fields than are removed by crops.ix
Excess nutrients in water cause harmful plant
growth—commonly referred to as “algal bloom,”
which can cause fish kills.x
Ammonia and Nitrates
Livestock manure is high in ammonia concentrations, xiv
and dissolved ammonia in water is not only highly toxic to fish,
xvi but can also be converted to dangerous nitrates.xvi
Elevated nitrate levels in drinking water are highly poisonous
to humans, causing potentially fatal oxygen levels in babies
(known as “blue-baby syndrome”), spontaneous
abortions, and possibly cancer.xviiIn a sample of
wells surveyed by the US Geological Survey from 1993 to 2000, 2
percent of public-supply and 9 percent of the domestic wells
more common in rural areas were found to have nitrate
concentrations higher than the EPA’s maximum allowable
level.xix The EPA estimates that about 1.3 million
households in counties with industrial livestock facilities get
their water from wells with dangerously high nitrate levels.xix
Pathogens and other
microorganisms
Manure contains a high level of pathogens (disease-causing
microorganisms). When the waste is applied to fields, those
pathogens can be transferred to local water supplies during a
run off from either irrigation or rainfall.xx The
impact of pathogens from manure is severe: according to the
Centers for Disease Control, in every waterborne disease
outbreak in the United States from 1986 to 1998 where the
pathogen could be identified, it most likely originated in
livestock.xxi
Some other waterborne microorganisms do not originate on
farms, but develop as a result of eutrophication caused by high
nutrient levels. Pfiesteria piscicida, for
example,thrives in many areas where algal blooms grow, and
causes lesions in fish and large-scale fish kills.xxii
It can also cause a range of symptoms in humans, including
respiratory and eye irritation, gastrointestinal problems,
fatigue, as well as skin problems and cognitive symptoms such as
memory loss and confusion.xxiii
Antibiotics and Hormones
Antibiotics and artificial growth
hormones are commonly used on
industrial farms, either injected directly into the livestock or
added to their feed.. Large amounts of both substances end up
being excreted by animals and can thus pollute water along with
everything else in livestock waste. Some hormones can remain
functional in manure up to 270 days after excretion, and there
have been many documented cases of hormones discovered miles
downstream of farms.xxiv Although it is unclear
whether these hormone concentrations can be high enough to
affect humans, they have been shown to compromise the
reproductive processes of fish.xxv
An estimated 75% of all antibiotics administered to
livestock are excreted, xxvi and for certain common
antibiotics that figure can be as high as 90%.xxvii
The overuse of antibiotics for livestock contributes to the
development of antimicrobial-resistant bacteria, and some
studies suggest that growth of these resistant bacteria may be
promoted in waterways with high levels of antibiotics.xxvii
Numerous studies have demonstrated that waterways are a
prominent means of transmitting these dangerous types of
bacteria to humans.xxix
Heavy Metals and Salts
Some heavy metals, such as copper and zinc, are essential
nutrients for animal growth—especially for cattle, swine,
and poultry.xxx However, such elements are often
present in animal feed in concentrations far higher than
necessary for animal health, along with other heavy metals such
as chromium, lead, arsenic and cadmium.xxxi Farm
animals excrete excess heavy metals in their manure—which
in turn gets spread as fertilizer, leading to soil and water
pollution. The health hazards resulting from exposure to heavy
metals in water include kidney problems from cadmium; nervous
system disorders, kidney problems and headaches from lead; and
both cardiovascular and nervous system problems from arsenic,
which is also known to cause cancer.xxxii
Many salts are also present in large quantities in
manure, including sodium, calcium, magnesium, potassium,
chloride, sulfate, bicarbonate, carbonate, and nitrate.xxxiii
When introduced to the environment, these salts increase the
salinity of waterways, leading to changes in aquatic ecosystems
and making water brackish, and therefore unfit for drinking.xxxiv
Organic Matter and Other
Solids
In addition to the biodegradable organic matter naturally
present in manure, animal bedding, wasted feed, soil, dust, hair
and feathers are often mixed with manure in storage and can end
up in waterways.xxxv The decomposition of organic
matter can cause increased levels of bacteria, which in turn
reduces oxygen levels in water and kills fish.xxxvi
This decomposition can also negatively affect the color, taste,
and smell of water.xxxvii
Water Usage and
Conservation
Agriculture uses a staggering amount of water on an annual
basis. In 2000, 41% of all freshwater used by humans in
the United States was used for agriculture.xlii
Perhaps even more notable is that agriculture accounted for more
than 80% of US “consumptive use” of water—that
share of water which is not returned quickly to the environment.xliii
Water overuse is particularly a problem on industrial
farms that do not tailor their farming practices on a case by
case basis. For example, a dairy that uses an automatic
“flushing” system to clean out its animal houses
uses an average of 150 gallons of water per cow per day,
compared to an average of 5-10 gallons used by farms that
monitor their water use in order to conserve it.xliv
Not only does water overuse hurt the environment, it’s
also expensive. One estimate from the USDA concludes that
increasing water use efficiency on irrigated farms by just 10%
could save almost $200 million per year solely due to the
associated savings in fuel costs.xlv
What You Can Do
Small, sustainable farms conserve water and apply waste and
fertilizer to fields responsibly, minimizing their impact on
local water systems. By supporting small farms such as
these, you can help to promote healthier waterways while
showing that you do not support the environmental recklessness
practiced by industrial farms.
- Visit the Eat
Well Guide to find a farm, store or restaurant near you
offering sustainably-raised meat and dairy products. Just enter
your zip code!
- Know your farmer. Visit your local
farmers’ market or join a CSA (community supported
agriculture group) and start buying from a farm directly. Ask
questions and get to know your food and how it is produced.
Check out Sustainable Table’s Shop Sustainable page to learn more.
Did You Know?
- The EPA considers agriculture to be
“the most widespread source of impairment in the
nation’s assessed lake acres.” xlvi
- In the US, 40% of rivers, lakes,
and coastal waters are so contaminated that they are unfit for
humans to fish in, swim in, or drink.xlvii
- An Ohio study revealed that 67
percent of water taken near poultry farms and 31 percent of
water near swine farms contained antibiotics.xlx
For More Information
Sources
|
