Earth Day 2003: A Celebration of 30 Years of Improvements in Nation’s Water Quality Using historical records and water quality data archived over the past 60 years, a retrospective study evaluates the impact of the 1972 Clean Water Act on long-term water quality trends in the nation’s rivers and estuaries. Previously elusive answers to critical questions about the effectiveness of the regulatory requirements of the 1972 Clean Water Act are now available in Progress in Water Quality: An Evaluation of the National Investment in Municipal Wastewater Treatment published by the U.S. Environmental Protection Agency in 2000 (www.epa.gov/owm/wquality/benefits.htm) and Municipal Wastewater Treatment: Evaluating Improvements in National Water Quality published in 2002 by John Wiley & Sons.

G. Tracy Mehan, III, EPA’s Assistant Administrator for Water, remarked that “under the Clean Water Act, the federal government invested well over $60 billion through the Construction Grants Program and the Clean Water State Revolving Fund to support the nation’s municipal wastewater infrastructure.” Federal, state and local government and private industry investments in water pollution control have achieved significant improvements in water quality. Water quality improvements, in turn, have brought about the restoration of fisheries and other vital environmental resources, the creation of water-based recreational opportunities and the economic revitalization of once abandoned waterfront property.  Mehan commended the study for being “the first national-scale study to provide a rigorous evaluation of the effectiveness of the effluent regulation policies in achieving the “fishable and swimmable” goals of the Clean Water Act.” The study supports the hypothesis that the 1972 Clean Water Act’s technology-based regulation of wastewater treatment facilities has achieved significant nation-wide environmental successes. While celebrating the successes of the Clean Water Act, the authors warn that if water pollution control infrastructure investments fail to keep pace with future population growth, the environmental benefits realized over the past 30 years may be lost to the next generation.

This important study has clearly confirmed a ‘before and after’ cause-effect relationship between the effluent limit regulations of the Clean Water Act and improvements in water quality in the nation’s rivers.

The quantity of oxygen-demanding pollutants dumped into the nation’s rivers by municipal wastewater plants decreased by 23% even while the nation’s population grew by 35% in the 30 years since passage of the 1972 Act.  The effect of the dramatic decline in wastewater loading on water quality, particularly under comparable critical low-flow conditions was confirmed by statistically significant national-scale improvements in worst-case dissolved oxygen levels in more than two-thirds of the nation’s river reaches.  Mehan commended the findings of the report and its nine case studies “as unequivocally showing how local water pollution control investments directly improved water quality, restored fisheries and other environmental resources, created recreational opportunities and revitalized once abandoned waterfront property.”  The case studies include the Connecticut River, the Hudson-Raritan estuary, the Delaware estuary, the Potomac estuary, the James estuary, the Chattahoochee River, the Ohio River, the Upper Mississippi River and the Willamette River.