Finally, attainment of national goals is also hindered by a lack of consistency in the environmental statistics reported by different states. One result is that in some cases, well-intentioned but basically flawed management strategies have increased environmental degradation as shown, for example, by the Ohio Environmental Protection Agency (1992). Fortunately, the U.S. Environmental Protection Agency (EPA) and others are becoming increasingly aware of these shortcomings and have initiated efforts such as the environmental indicators initiative and the Intergovernmental Task Force on Monitoring Water Quality (1992, 1993, 1995).
Beyond chemical contaminants, multiple factors are responsible for the continuing decline of surface water resources in Ohio (Ohio Environmental Protection Agency, 1995) and the United States (Benke, 1990; Judy et al., 1984). These include the modification and destruction of riparian habitat, sedimentation of bottom substrates, and alteration of natural flow regimes. Because biological integrity is affected by many factors, controlling chemicals alone does not assure its protection or restoration (Figure 1). We need a broader focus on the entire water resource if we are to successfully reverse the decline in the overall quality of the nation's waters. Therefore, ecological concepts and biological criteria must be further incorporated into the management of surface water resources.
Although a growing number of states and organizations rely primarily on biological indicators to assess the condition of their water resources, others choose to emphasize chemical and physical indicators. The following examples demonstrate the inherent risks of relying solely on these indicators.
Out of 645 stream and river segments analyzed in Ohio, biological indicators revealed impairment in 49.8 percent of the segments where chemical indicators detected none (Ohio Environmental Protection Agency, 1990; Rankin and Yoder, 1990a). The converse was true for only 2.8 percent of stream segments. The remarkable discrepancy between biological and chemical assessments is due to fundamental differences in what they measure. Biological communities respond to a wide variety of chemical, physical, and biological factors. Thus, biological indicators are able to detect a wider range of environmental disturbances than can measures of chemical water-quality alone.
Another example is the proportion of waters that various states reported were