SCWRC Report ANIMAL AGRICULTURE AND WATERSHED IMPAIRMENT IN SOUTH CAROLINA A GIS-Based Spatial Assessment

Animal agricultural pollution remains one of the most challenging watershed problems. As reduction of the pollution becomes the top priority in the Clear Water Action Plan and states are required to implement the non-degradation policy, understanding the characteristics of animal agriculture, watershed impairment and their relationships at the state level are very important for making proper decisions. This research attempted to examine the relationship between animal agriculture and watershed impairment in South Carolina from a GIS-based spatial, empirical approach. Animal agriculture was represented by cattle, poultry and swine operations that were measured in terms of animal population, farms, facilities and units as well as their derived variables. Watershed impairment was measured in terms of priority ranks for dissolved oxygen (DO), fecal coliform (FC) bacteria, phosphorus (P), or pH problems based on the 2000 303(d) list. Multiple techniques and models, which include map overlay, spatial summary, canonical correlation, multiple regression, and Pearson correlation, were used to determine how strong the relationships are, which animals have larger impacts and where the problem areas are. It was found that 155 out of 274 watersheds in the 11-digit hydraulic units have been impaired by DO, FC, P, or pH problems, among which fecal coliform bacteria are the most widely spread problems in South Carolina. The results of both spatial and statistical analyses indicate that there are only very weak, though statistically significant, associations between animal agriculture and the impairments in this state. This suggests that there are some non-animal agriculture factors that are major contributors of watershed impairment problems in concern. Nevertheless, cattle facilities appear to have slightly larger impacts on watershed quality than poultry farms do whereas swine operations are not a negative factor that aggravates the watershed impairment in this state. In addition, 28 maps were generated to demonstrate the distribution of watershed impairment, animal agriculture and their relationships. Some problem areas have been identified. It is recommended that (1) state policies on animal regulations and environmental standards acknowledge the differences among impairment types, animal groups and geographic regions; (2) more efforts be made in the control and reduction of pollution from cattle feeding operations especially in the areas with higher priority ranks and larger clusters of animal facilities that have been identified in the research; and (3) more resources be used in the identification and control of non-animal agricultural factors that are the major causes of DO, FC, P and pH …