Historical information on Tennessee Eastman Division's waste-water treatment capability and BOD loading to the South Fork Holston River is provided in Figure 2. In 1966, Eastman converted from the use of simple settling ponds to biological waste-water treatment with aerated lagoons. From the late 1960s to the early 1970s, company efforts focused on minimizing waste streams and eliminating waterborne discharges. Combustion units with energy-recovery boilers were constructed to incinerate wastes that were isolated from manufacturing processes. By the early 1970s, these activities resulted in a 65 percent reduction in the Tennessee Eastman BOD loading to the South Fork Holston River.
Data on aquatic invertebrates and fish collected at a location downstream of all Kingsport area point-source discharges, before and after this BOD load reduction, showed a 140 percent increase in the total number of species of invertebrates and fish, from 15 species in 1965 to 36 species in 1974.
In 1976, Tennessee Eastman Division again improved its waste-water treatment capability by installing an activated-sludge treatment system. This change, combined with continued emphasis on waste minimization, resulted in additional improvements that amounted to a 96 percent reduction in Tennessee Eastman's BOD loading between 1967 and the early 1980s. Other point sources in the Kingsport area also achieved load reductions during this period. As a result, there was a 210 percent increase in the total number of species of invertebrates and fish, from 15 species in 1965 to 47 species in 1980.