MORRISON, Wis. — All it took was an early thaw for the drinking water here to become unsafe.
Damon Winter/The New York Times
Runoff of waste from farm animals is said to be a source of pollutants in drinking water.
There are 41,000 dairy cows in Brown County, which includes Morrison, and they produce more than 260 million gallons of manure each year, much of which is spread on nearby grain fields. Other farmers receive fees to cover their land with slaughterhouse waste and treated sewage.
In measured amounts, that waste acts as fertilizer. But if the amounts are excessive, bacteria and chemicals can flow into the ground and contaminate residents’ tap water.
In Morrison, more than 100 wells were polluted by agricultural runoff within a few months, according to local officials. As parasites and bacteria seeped into drinking water, residents suffered from chronic diarrhea, stomach illnesses and severe ear infections.
“Sometimes it smells like a barn coming out of the faucet,” said Lisa Barnard, who lives a few towns over, and just 15 miles from the city of Green Bay.
Tests of her water showed it contained E. coli, coliform bacteria and other contaminants found in manure. Last year, her 5-year-old son developed ear infections that eventually required an operation. Her doctor told her they were most likely caused by bathing in polluted water, she said.
Yet runoff from all but the largest farms is essentially unregulated by many of the federal laws intended to prevent pollution and protect drinking water sources. The Clean Water Act of 1972 largely regulates only chemicals or contaminants that move through pipes or ditches, which means it does not typically apply to waste that is sprayed on a field and seeps into groundwater.
As a result, many of the agricultural pollutants that contaminate drinking water sources are often subject only to state or county regulations. And those laws have failed to protect some residents living nearby.
But thousands of large animal feedlots that should be regulated by those rules are effectively ignored because farmers never file paperwork, E.P.A. officials say.
And regulations passed during the administration of President George W. Bush allow many of those farms to self-certify that they will not pollute, and thereby largely escape regulation.
In a statement, the E.P.A. wrote that officials were working closely with the Agriculture Department and other federal agencies to reduce pollution and bring large farms into compliance.
Agricultural runoff is the single largest source of water pollution in the nation’s rivers and streams, according to the E.P.A. An estimated 19.5 million Americans fall ill each year from waterborne parasites, viruses or bacteria, including those stemming from human and animal waste, according to a study published last year in the scientific journal Reviews of Environmental Contamination and Toxicology.
The problem is not limited to Wisconsin. In California, up to 15 percent of wells in agricultural areas exceed a federal contaminant threshold, according to studies. Major waterways like the Chesapeake Bay have been seriously damaged by agricultural pollution, according to government reports.
In Arkansas and Maryland, residents have accused chicken farm owners of polluting drinking water. In 2005, Oklahoma’s attorney general sued 13 poultry companies, claiming they had damaged one of the state’s most important watersheds.
The Danger of Livestock Waste
As Idaho dairies have grown, so has the environmental problem of coping with all the fecal waste. Much of it is spread over fields, where it can seep into local aquifers that supply people's wells.
It is often difficult to definitively link a specific instance of disease to one particular cause, like water pollution. Even when tests show that drinking water is polluted, it can be hard to pinpoint the source of the contamination.
Despite such caveats, regulators in Brown County say they believe that manure has contaminated tap water, making residents ill.
“One cow produces as much waste as 18 people,” said Bill Hafs, a county official who has lobbied the state Legislature for stricter waste rules.
“There just isn’t enough land to absorb that much manure, but we don’t have laws to force people to stop,” he added.
In Brown County, part of one of the nation’s largest milk-producing regions, agriculture brings in $3 billion a year. But the dairies collectively also create as much as a million gallons of waste each day. Many cows are fed a high-protein diet, which creates a more liquid manure that is easier to spray on fields.
In 2006, an unusually early thaw in Brown County melted frozen fields, including some that were covered in manure. Within days, according to a county study, more than 100 wells were contaminated with coliform bacteria, E. coli, or nitrates — byproducts of manure or other fertilizers.
“Land application requirements in place at that time were not sufficiently designed or monitored to prevent the pollution of wells,” one official wrote.
Some residents did not realize that their water was contaminated until their neighbors fell ill, which prompted them to test their own water.
“We were terrified,” said Aleisha Petri, whose water was polluted for months, until her husband dumped enough bleach in the well to kill the contaminants. Neighbors spent thousands of dollars digging new wells.
At a town hall meeting, angry homeowners yelled at dairy owners, some of whom are perceived as among the most wealthy and powerful people in town.
One resident said that he had seen cow organs dumped on a neighboring field, and his dog had dug up animal carcasses and bones.