blogpost water quality

Agricultural Runoff

Soybean farm in North Carolina. Soybeans are grown in Alexander County, among others, which borders the Catawba River.

Agriculture is one of the leading industries in North Carolina, contributing $78 million to the state’s economy and employing 16% of the state’s workforce. The piedmont and foothills regions of NC are home to livestock, nurseries, field crops, and even aquaculture. The presence of these farms inevitably results in the use of fertilizers, pesticides, and other factors by farmers seeking to maintain good health and to promote growth. While the use of such compounds is not innately harmful, the agriculture industry presently poses a threat to surface water quality because of a lack of proper runoff regulation enforcement. Agricultural runoff deserves to be treated as a special issue of sedimentation because of the complex nature of the laws governing it and because of the unique pollutants it contains.

poultry
A poultry farm in the Catawba River Basin.

In the counties that border the Catawba River, poultry makes up the greatest percentage of the livestock industry, and it is currently growing. Poultry farmers, along with those of swine and turkey, commonly use organoarsenic compound roxarsone to induce weight gain in broilers (5-12 week chickens used for their meat). This compound is largely excreted and sequesters in the litter that lines holding pens. When this litter is removed, it is either land-applied or stockpiled for later application, uncovered on bare soil, and in both cases Arsenic has been shown to leach into the soil, leading to the danger of both ground and surface water contamination. Turkey litter also contains nitrates and phosphates, but the main sources of these compounds are the fertilizers and pesticides used for nurseries and field crops.

While the nitrates and phosphates in fertilizers are useful in promoting plant growth and occur in water and soil naturally, they are harmful when they accumulate in surface waters in excessive amounts. Under the right conditions, these nutrients can induce algal blooms that have various negative consequences for the surrounding environment.

alga
Red algal bloom in Lake Wylie, a reservoir on the Catawba River.

Some algae produce toxins that are harmful to various aquatic species and their predators, but most simply cause harm by blocking sunlight, disrupting habitats, and clogging fish gills. Algal blooms also result in deoxygenation of surface water, which can lead to fish die-offs or dead zones, where the water is no longer habitable. Increased algal and plant life in aquatic systems can even result in eutrophication, where photosynthetic organisms take advantage of a particular resource abundance and dominate a body of water. Some current nursery and field crop watering techniques, such as overhead watering, are inefficient or relatively ineffective; because of this, more fertilizers and pesticides must be used in order to cause the desired effects, resulting in more nutrients being introduced to the soil than is necessary. This inefficiency also means that more water must be used in general, leading to the wasting of a valuable resource and increases in erosion and sedimentation.

Though agriculture and related industries are strangely not bound by the Sedimentation Pollution Control Act of 1973 (§ 113A-52.01), agriculture is regulated by a plethora of other federal and North Carolina laws, beginning with the Water Pollution Control Act of 1972. A brief list of other important laws includes the Wilful Discharge Act of 1992, the Clean Water Responsibility and Environmentally Sound Policy Act of 1997, and the North Carolina Clean Water Act of 1999. These acts present a powerful and wide-ranging combination of legislative regulations, inspection commissions, and enforcement organizations, with the Division of Environmental Management (DEM) being the top enforcer. Nevertheless, the fact that issues due to contaminants from agricultural runoff continue to be observed in the Catawba river implies that enforcement is not utilized enough. This is further evidenced by the fact that instances of unpermitted or unreported agricultural also persist. Alternatively, it suggests that current techniques of irrigation and managing agricultural runoff are inadequate. Collectively, this information indicates that a review of DEM inspection enforcement is necessary, as well as developing and implementing more effective irrigation and waste control methods.

Sources

“Agricultural Statistics – Summary of Commodities by County (2014).” North Carolina Department of Agriculture & Consumer Services. 9 Dec. 2015. Web.

Barker, James C. “History of Water Quality Rules and Regulations.” Animal Waste Management. 22 Feb. 2016. Web.

Chislock, Michael F., Enrique Doster, Rachel A. Zitomer, and Alan E. Wilson. “Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems.” Suitable by Nature Education. 2013. Web.

“The Effects: Environment.” United States Environmental Protection Agency. 27 Jan. 2016. Web.

N.C. Gen. Stat. § 113A-50-69.

“North Carolina Agriculture Overview.” North Carolina Department of Agriculture & Consumer Services. 7 Apr. 2015. Web.

Shah, Sanjay B., Grabow, Garry L., Dean L. Hesterberg, Rodney L. Huffman, Kim J. Hutchison, David H. Hardy, and James Parsons. “Leaching Potential of Arsenic and Other Pollutants from Turkey Litter Stockpiled on Bare Soil.” Ed. Sanjay B. Shah. Southern Animal Manure and Waste Management Quarterly (15 Sept. 2006): 1-2. Print.

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