Progress in Water Quality: An Evaluation of the National Investment in MunicipalWastewater Treatment. Executive Summary

摘要

The national investment is demonstrated by the increase in the number of peopleserved by (POTW), which shifted dramatically between 1968 (before CWA) (Clean Water Act) and 1996 (after CWA). The overall number of people relying on POTWs with less than secondary treatment dropped rapidly after passage of the 1972 CWA. In 1968 about 39 percent (54.2 million) of the 140.1 million people served by POTWs received less than secondary treatment (raw and primary). By 1996 this percentage was reduced to about 9 percent (17.2 million) of the 189.7 million people served by POTWs. While the number of people served by POTWs with secondary treatment remained fairly constant between 1968 and 1996 (a slight decrease of 3.7 million people or about 4 percent of the population), the number of people provided with greater than secondary treatment increased significantly (from 0.3 million people in 1968 to 82.9 million people in 1996).