ANS conducted baseline studies of the White River in 1974 and 1976 before manufacturing operations started at Arkansas Eastman Division. These studies were aimed at generating data for use in comparison with future studies and to assess the natural variability in resident populations of aquatic life.

The 1980 and 1991 ANS studies used three types of analysis to assess the potential effects of Eastman operations on the White River: comparisons of the 1980 and 1991 data with baseline data from 1974 and 1976; comparisons of upstream and downstream data; and comparisons of left-bank and right-bank data. These analyses were designed to show evidence of impact due to discharges by Arkansas Eastman, for example if the biological parameters at sampling locations or over time changed in a pattern consistent with exposure to point-source pollution.

Table 1 shows the number of noninsect macroinvertebrate, insect, and fish species collected at stations immediately upstream and downstream of the Arkansas Eastman discharges to the White River. These and other data collected during the studies on species richness and abundance show differences among the sampling locations, but the observed patterns are not consistent with a negative effect from the Eastman facility. All indications are that the water-quality management systems in place at Arkansas Eastman are successfully protecting the White River.

ANS river studies have made significant contributions to Eastman's ''plan, do, check, and act" approach to improving and maintaining water-quality management systems. The case studies for Tennessee Eastman and Arkansas Eastman illustrate the importance of developing and understanding the effects that water-quality initiatives have on the resources they are meant to protect. For Arkansas Eastman management, the studies provide reassurance that the systems in place to protect the White River are functioning as planned. At Tennessee Eastman, the