Feces in water typically comes from leaking septic tanks, agricultural runoff or animal droppings. If water contains feces, it could also contain disease-producing bacteria or viruses that can exist in the feces. These diseases include typhoid fever and hepatitis A.
The maximum amount of pollution a body of water can have without violating state water-quality standards is called the Total Maximum Daily Load. Fecal pollution is a major contributor to TMDLs for Georgia watersheds.
Most fecal pollution comes from nonpoint sources. So far, there has been no proven way to know where or from what animal it came. And if you can't locate the problem, you can't fix it.
Peter Hartel, UGA CAES researcher, works to build a DNA library that will identify points of pollution in Georgia watersheds.
Peter Hartel is an associate professor of crop and soil science in the University of Georgia College of Agricultural and Environmental Sciences. For the past two years, he's been an environmental detective.
Hartel uses a type of DNA fingerprinting that can tell what animal caused the fecal pollution of a specific watershed.
Using a process called ribotyping, Hartel can make a DNA fingerprint, a series of distinct bands, of the Escherichia coli. This bacterium is found in all warm-blooded animal feces.
A few years ago, scientists believed E. coli was the same in all animals. But it's not. Different animals have different types.
"Dog E. coli is found only in dogs. Human E. coli is found only in humans. The same with cows and poultry," Hartel said. "We're not sure why that is right now. But we know they're different."
After you have a library of the distinct E. coli fingerprints of various animals, the rest, in theory, is easy, Hartel said.
You can monitor and take samples of a watershed, isolate the different E. coli found in the water and compare that to the library of animal samples. That will tell you what animal feces are in the water, Hartel said.
Building the Library
When Hartel began his research, there was little information on
ribotyping to identify pollution sources in water. He's changing
So far, his E. coli fingerprint library has samples from several Georgia animals, including beef cattle, swine, poultry and Canada geese. But he needs more.
"There has to be an established library to compare and identify samples against," Hartel said. "The more extensive the source library, the greater the likelihood of obtaining matches."
A Timeline of Water
Other states are also using ribotyping to better understand pollution, said Alan Hallum, chief of the water protection branch of the Georgia Environmental Protection Division. But Georgia could lead the way.
If there is a public health problem in a watershed, Hallum said, this test could better target what needs to be done in the watershed to correct the problem as quickly and as economically as possible.
"I would like to have, from a state regulatory standpoint, a way to know we're not spending money unnecessarily," Hallum said. "This (test) allows the stakeholders in a watershed to do a best-management approach to fixing a problem."