Less than a decade after enactment of the 1972 CWA, Congress and the public began to raise policy questions about the national-scale effectiveness of the technology-based controls of the CWA. In attempting to provide some answers to these questions, case studies of water pollution control and water quality management were compiled for a number of streams, rivers, lakes, and estuarine waterbodies. To meet a variety of objectives, both anecdotal and quantitative data and information have been collected for case studies evaluating water quality conditions.

Anecdotal accounts of historical water pollution problems and changes in the water quality of streams, rivers, estuaries, and coastal waters that had been achieved by the early 1980s were reported by state agencies and compiled by USEPA (1980) and the Association of State and Interstate Water Pollution Control Administrators (ASIWPCA, 1984). Twenty-five years after enactment of the 1972 CWA, USEPA (1997) and the Water Environment Federation (WEF, 1997) reported on the substantial water quality improvements that had been achieved in rivers, lakes, estuaries, and coastal waters. Based on anecdotal evidence, these reports concluded that the CWA had produced substantial gains in water quality. No quantitative data were presented, however, in either of these reports to support the conclusion that the goals of the CWA were being achieved.

In a 1988 quantitative synthesis of before-and-after studies, USEPA (1988) compiled the results of 27 case studies to document water quality changes that had resulted from upgrades to municipal wastewater treatment facilities (primary to secondary, or secondary to advanced treatment). With the exception of only a few cases (e.g., Potomac estuary near Washington, DC, and Hudson River near Albany, New York), most of the 27 cases accounted for both minor and major facilities (< 0.1 to 30 mgd) discharging to small receiving waters with 7Q10 low flows ranging from < 1 cfs to 100 cfs. Based on pollutant loading and water quality data sets, 23 of the 27 case studies were characterized by at least moderate improvements in water quality conditions after upgrades of the POTWs. Included in USEPA's 1988 synthesis were the well-documented before-and-after findings of Leo et al. (1984), based on 13 case studies of water quality changes that were linked to upgrades from secondary to advanced treatment. Also included in USEPA's synthesis were four case studies prepared by GAO (1986a) of municipal wastewater treatment plant upgrades for rivers in Pennsylvania: Lehigh River, Allentown (30 mgd); Neshaminy Creek, Lansdale (2.36 mgd); Little Schuykill River, Tamaqua (1.09 mgd); and Schuykill River, Hamburg (0.46 mgd).

A number of case studies other than those presented in this book have documented trends in improvements in water quality conditions and biological resources following site-specific upgrades. Estuarine case studies of pollutant loading, water quality trends, fisheries, and other biological resources have been prepared for Narragansett Bay (Desbonnet and Lee, 1991), Galveston Bay (Stanley, 1992a), the Houston Ship Channel (EESI, 1995), and Pamlico-Albemarle Sound (Stanley, 1992b).

For Lake Washington in Seattle, Edmondson (1991) documented the long-term ecological impact of the diversion during the mid-1960s of municipal wastewater on cultural eutrophication and recovery of a large urban lake. The rejuvenation of Lake Erie, declared "dead" during the 1960s, is positive evidence that the regulatory controls of the 1972 Clean Water Act and the 1972 Great Lakes Water Quality Agreement between Canada and the United States, designed to mitigate bottom water hypoxia and cultural eutrophication by reducing pollutant loads of organic matter and phosphorus, have been successful in greatly improving water quality (Burns, 1985; Charlton et al., 1995; Sweeney, 1995) and ecological conditions (Krieger et al., 1996; Koonce et al., 1996; Makarewicz and Bertram, 1991) in this once ecologically devastated lake. The Cuyahoga River, a major tributary to Lake Erie at Cleveland, Ohio, sparked national attention when the river caught fire in 1969, helping to push the U.S. Congress to pass the Clean Water Act in 1972 (NGS, 1994). Three decades after the

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