In the majority of counties in the SAA area, less than 30 percent of the land base is devoted to agriculture. Those counties with more land in agriculture do not necessarily have greater estimated erosion potential, but often do have grater estimated nitrogen loading from fertilizer and animal manure. Population in the SAA increased 19 percent from 1970 to 1980. Growth increased 7 percent more in the next 10 years. Development of housing, service facilities, and roads to serve the growing population generally increases impacts on water quality.
Forest comprises the primary land cover of the region.
Unlike agriculture, forestry activities that disturb soil are dispersed in both space and time. Thus, forestry has a lower potential impact on aquatic resources. Waters with estimated high BOD loading are often in watersheds that have more miles of stream that do not support designated uses. A total of 17 fish consumption advisories have been issued in the SAA area, each state having at least one of these advisories. In 1990, approximately two-thirds of the water use within the study area was industrial, with the remainder divided between commercial, domestic, and agricultural.