For years, members of Congress, as well as citizens and special interest, environmental, and business groups, have been quizzing the USEPA about the benefits gained from the nation's extraordinary public and private investment in wastewater treatment (GAO, 1986a, 1986b, 1986c; USEPA, 1988). Addressing their questions is a difficult task because environmental systems are very complex—so complex, in fact, that researchers can't even agree what "stick" to use to measure success. Consequently, a number of tools have been applied in an attempt to measure the success of water pollution control efforts. These include:
• Reporting the number of discharge permits issued, enforcement actions taken, and other administrative actions and programmatic evaluations (Adler et al., 1993).
• Reporting on the number of POTWs built or upgraded, population served by various treatment levels, effluent loading rates, and other trends in the construction and use of wastewater infrastructure (USEPA, 1997b).
• Inventorying state and national waterways meeting designated uses (e.g., reports prepared by states to comply with CWA section 305(b), USEPA's 305(b) summary reports to Congress) (ASIWPCA, 1984; USEPA, 1995a, 1995b).
• Investigating changes in specific waterways following wastewater treatment plant upgrades (GAO, 1978, 1986c; Leo et al., 1984; Patrick et al., 1992).
• Investigating the statistical significance of national-scale changes in water quality following the 1972 CWA (GAO, 1981; Knopman and Smith, 1993; Smith et al., 1987a, 1987b).
Although each of the above approaches provides some evidence of the accomplishments of municipal wastewater treatment under the CWA, none could be considered a comprehensive assessment of national progress in meeting the CWA's main goal of maintaining, or restoring, fishable and swimmable waters. Clearly, a fresh measuring stick is needed—one that is simple enough to provide nonscientists with evidence of the overall success or failure of the act, yet rigorous enough to stand up to the scrutiny of people who make their living analyzing water quality data trends.
This book takes a unique, three-pronged approach for answering the prima facie question: Has the Clean Water Act's regulation of wastewater treatment processes at POTWs been a success? Or posed more directly: How have the nation's water quality conditions changed since implementation of the 1972 CWA's mandate for secondary treatment as the minimum acceptable technology for POTWs? The three-
pronged approach described below was developed so that each study phase could provide cumulative support regarding the success, or failure, of the CWA-mandated POTW upgrades to at least secondary treatment. Using the analogy of a three-legged stool, the study authors believed that each leg must contribute support to the premise of CWA success. If one or more legs fail in this objective, the stool will, in the words of Mark Twain, be "limber" and unable to "stand up."
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