Animal Wastes as a Source of Drinking Water Contamination
Animal production facilities can be a source of drinking water contamination if wastes are not properly managed. Microorganisms , nitrogen, and phosphorus are the prime contaminants from manure. There are various types of microorganisms present in fecal waste that cause severe illness and disease if ingested. Excessive amounts of nitrogen, in the nitrate form, which is converted to the nitrite form in the body, will prevent oxygen from binding to hemoglobin in the blood. Infants are especially sensitive to excess nitrite and can suffer methemoglobinemia, or "Blue Baby Syndrome".
Farmers collect liquid manure in catchment ponds or lagoons where it can be degraded by anaerobic bacteria, sunlight, and water. Anaerobic bacteria promote the decomposition of carbon-containing compounds into carbon dioxide and methane, as well as nitrogen into ammonia and ammonium. Farmers often use the lagoon liquid, which is partially treated waste, as fertilizer in order to take advantage of the nutrients in the manure (3). Bacteria and other microorganisms are filtered out by the soil, but can enter surface water resources in run-off if waste application rates are high and the soil becomes saturated. Saturation of soil can also contribute to contamination of ground water sources. Contamination may result if waste water is applied to fields located adjacent to a stream or lake. Contamination also occurs when lagoons leak. Liquid seeping from a lagoon appears to pose a human health concern only if shallow drinking water wells are located immediately downhill from the lagoon (3). Often, agricultural regions depend upon sunken private wells for drinking water, and since federal regulations do not require monitoring of private wells, it is up to the owner or user to test thier drinking water.
There are many protective practices that can can be employed in order to decrease the possibility of water contamination from animal wastes. These practices are often referred to as Best Management Practices (BMP's) (2). A few of these include:
The University of Georgia, College of Agriculture and Environmental Sciences, is a good resource for learning more about animal waste and the environment.
The federal Water Pollution Control Act prohibits the discharge of large quantities of waste to waters without a permit. This includes feedlots, which are often considered 'concentrated' operations. If feedlots have at least 1,000 animal units and are maintained for 45 days or more in a non-vegetated area, they fall under the National Pollutant Discharge Elimination System (NPDES) permitting program (1). This program requires that those businesses and households that fall under its guidelines obtain permits in order to discharge wastes. Certain states may require more stringent standards, and some states require ground and surface water monitoring.
1. U.S. E.P.A. National Pollution Discharge Elimination System (NPDES) Permit Program. URL: http://www.epa.gov/OWM/wm045000.htm
2. Hammond, C. Animal Wastes and the Environment. October 1994. University of Georgia, College of Agriculture and Environmental Sciences. URL: http://www.ces.uga.edu/pubcd/c827-w.html.
3. Water Quality and the North Carolina Swine Industry. March 10, 1995.URL: http://www.ces.ncsu.edu/whpaper/WQswine.html
This page was prepared by T.L.
Pedersen, June 1997, UCD EXTOXNET FAQ Team.
Revised by B.T. Johnson, October 1997