The second leg of this study focused on the use of large national databases and statistical methods to examine temporal and spatial trends in DO conditions nationwide. However, the uniqueness of each waterway and the activities surrounding it requires an investigation to go beyond STORET to identify, quantify, and document in detail the specific actions that have resulted in water quality improvements and associated benefits to water resource users.
In the third and final leg of this study, nine urban waterways have been selected to characterize changes in population, point source effluent loading, water quality, and environmental resources before and after the CWA:
These waterways were selected to represent heavily urbanized areas with historically documented water pollution problems. A variety of data sources, including the scientific literature, USEPA's national water quality database (STORET), and federal, state, and local agency reports, were used to characterize long-term trends in population, point source effluent loading rates, ambient water quality, environmental resources, and recreational uses. Additional information was obtained from validated
• Connecticut River
• Hudson-Raritan estuary
• Chattahoochee River
• Delaware estuary
• Potomac estuary
• James estuary
• Upper Mississippi River
• Willamette River water quality models for the Delaware, Potomac, and James estuaries and Upper Mississippi River case studies to quantify the water quality improvements achieved by upgrading municipal facilities to secondary and better levels of treatment as mandated by the 1972 CWA.
Chapter 4 presents an overview of the case study assessment approach and provides background on previous efforts that have used case studies to examine long-term changes in water quality conditions in the United States. Chapter 4 also summarizes the overall findings for the nine urban waterways; detailed assessments are provided for each case study in Chapters 5 through 13.
Was this article helpful?