An analysis of the existing water quality data for the James River estuary has been conducted to document the historical changes in wasteloads and the water quality improvement in the estuary from 1971 to the mid-1990s. A water quality model for the upper James estuary was modified to include the lower portion of the estuary (Lung and Testerman, 1989). This modified model was calibrated and verified using three sets of water quality data. Finally, the verified model was used to evaluate the water quality improvement due to the treatment upgrades from primary to secondary at the POTWs. Altogether, six simulation scenarios, incorporating different ambient environmental conditions and wasteload levels, were developed for evaluation.
The analysis of POTW wasteloads indicated significant reduction of BOD5 discharged into the James estuary starting in the early 1970s. By the mid-1980s, many POTWs had achieved high degrees of carbon removal with treatment levels beyond secondary. Nutrient reduction did not start until 1988, when the phosphate detergent ban became effective.
A review of the historical water quality data showed the improvement of DO conditions in the James estuary from a DO sag of much lower than 5 mg/L in 1971 to levels consistently above 5 mg/L in the 1980s. Nutrient concentrations in the water column of the James estuary have remained quite stable over the past 30 years. The model results showed a clear, progressive rise in DO levels in the estuary from primary treatment to secondary treatment, and to treatment beyond secondary at the POTWs. Based on the analyses of historical wasteload data, water quality data, and model results, it can be concluded that the treatment upgrades from primary to secondary and better levels of treatment at POTWs provided significant water quality improvement in the James River basin. With the cleanup of the James River, visitors to Richmond, Virginia, can enjoy a riverboat dinner cruise or a stroll along the refurbished 2-mile canal walk. More adventurous visitors can challenge themselves by rafting and kayaking on the only Class IV white water located in an urban river in the nation (McCulley, 1999). Birds and fish are also making a remarkable recovery in the James River basin in response to water quality improvements.
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