The Number One Menace - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 37

Aside from pathogens such as E.coli,manure also contains nutrients, such as phos-
phorus and nitrogen, that, in excess, can create havoc in the ecosystem. Phosphorus
is a common supplement used to stimulate milk production; but many farmers add
more phosphorus than necessary, just to “make sure” their cows lactate productively.
Nitrogen originates in cattle feed, such as distillers' grains, the waste let over from corn
fermentation, which supplies dairy cows with protein. (Distillers' grains cause cows
to produce greenhouse gases—including ammonia, methane, and other volatile com-
pounds—which has stirred a debate over agricultural air pollution.) Cattle in the United
States excrete some 3 million pounds of phosphorus and 8 million pounds of nitrogen
a day.
When manure is spread on fields, crops absorb some of these nutrients, but the ma-
jority is washed off the land into waterways. This can cause human health problems,
such as cyanosis, in which the hemoglobin in blood is deoxygenated (commonly known
as the blue baby syndrome, because tissues low on oxygen fill with dark, deoxygenated
blood, which gives the skin a blue cast). Moreover, excess nutrient flows in agricultural
regions—from the Great Lakes to the Sacramento Delta—have caused vast algal
blooms, which block sunlight and absorb oxygen, creating lifeless underwater deserts
known as dead zones.
While researchers look for new ways to use manure, such as converting it into gas
to produce electricity (Threemile Canyon has built a pilot manure “digester” that traps
methane gas for use as fuel), water experts say the best way to reduce agricultural run-
off is to strengthen pollution laws and empower regulators to enforce them. As the law
stands now, the EPA cannot shut down a farm or block it from expanding, even when
its manure runoff threatens water supplies.
Despite its known hazards, agricultural runoff is poorly regulated. The Clean Water
Act is focused on the quality of water in pipes and ditches and does not address more
complex scenarios, such as when manure sprayed onto a field seeps into groundwater.
This type of nonpoint-source pollution is governed by state laws, which are often weak
or not well enforced. What's more, many farmers do not ile the requisite paperwork
and are rarely fined for polluting water. Under President George W. Bush, regulations
were loosened to allow farms to “self-certify” that they would not pollute; many experts
were not surprised when this resulted in an increase in agricultural runoff.
The EPA has instituted special rules to regulate runoff from the thousands of large
CAFOs (defined by the EPA as a farm that keeps more than 700 dairy cows, 1,000 cattle,
2,500 swine, 55,000 turkeys, or between 30,000 and 125,000 chickens) that are cropping
up across the country. Yet those rules have done little to stem the tide of manure that is
infiltrating water supplies.