CWA. Great progress has been achieved in improving DO conditions in New York Harbor, the Chattahoochee River, the Delaware River, and the Potomac River.
Water quality improvements in other constituents, including BOD5, suspended solids, coliform bacteria, heavy metals, nutrients, and algal biomass, have also been linked to reductions in municipal and industrial point source loads for many of the case studies. Figure 4-3 correlates long-term trends in the reduction of effluent loading of BOD5 with improvements in summer DO in the Hudson-Raritan estuary (New York City), the Upper Potomac estuary (Washington, DC), the Upper Mississippi River (Minneapolis-St. Paul, MN), and the Willamette River (Portland, OR). Finally, improvements in water quality have also been linked to the post-CWA restoration of important biological resources (e.g., fisheries and submersed aquatic vegetation in the Potomac estuary) and increased recreational demand and aesthetic values of waterways once considered extremely unsightly (e.g., Upper Mississippi River).
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