The poet Sidney Lanier, who praised the Chattahoochee in his "Song of the Chattahoochee," would not have been so inspired during the 1940s, 1950s, and 1960s. The Chattahoochee River was characterized by poor water quality for a reach of 70 miles below Atlanta. The first 40 miles were described as "grossly polluted," and responsi bility was attributed to inadequately treated wastewater, particularly from Atlanta's R. M. Clayton sewage treatment plant, at the mouth of Peachtree Creek (EPD, 1981). Figure 10-6 shows the effect Atlanta's wastewater discharges historically have had on the water quality of the Chattahoochee River, with DO levels drastically depleted downstream of Atlanta near State Road (SR)-92 (River Mile 280). At Fairburn, an average of 13 percent of the river flow consisted of wastewater (Stamer et al., 1979). From July through October, heat and low flow placed the river in near septic conditions, with DO below 4 mg/L 64 percent of the time. During the period from 1968 to 1974, DO concentrations were 64 percent less in the summer months than in January and minimum DO levels were consistently below 1 mg/L (EPD, 1981). In 1973, DO concentrations dropped to zero during September. As of 1972, the R. M. Clayton plant was still releasing large quantities of wastewater receiving only primary treatment. Fecal coliform densities, ammonia-N, BOD5, and suspended solids concentrations continued to be high above and below the discharge at Peachtree Creek. Fish kills caused by discharges of raw sanitary sewage and industrial chemicals were commonplace before 1976 (Mauldin and McCollum, 1992).
Rainfall in the area results in overflows from combined sewer systems (CSOs) and large amounts of urban runoff, contributing to large dissolved and suspended constituent loads to the river. Twelve CSOs have been identified in the watershed (Mauldin and McCollum, 1992). Low-flow periods result in less dilution of wastewater, resulting in low DO concentrations, high BOD5, high fecal coliform densities, and other problems.
A severe drought in 1988 caused the DO level to dip below 4 mg/L in the study region from April to August (Mauldin and McCollum, 1992). A major fish kill occurred
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