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water year flow conditions therefore represents a conservative approach to the assessment of Biochemical Oxygen Demand(BOD) <br /> potential impacts of the proposed project on the receiving water quality. <br /> Data Availability: DWR-MWQI monitoring data from the San Joaquin River at Mossdale(just <br /> Near-Field Analysis and Results downstream of the WQCF discharge)corresponding to a dry water year were used to calculate <br /> The analysis and results for each constituent specified in Table 7 selected for near-field analysis an estimated impact of WQCF effluent biochemical oxygen demand(BOD)in the San Joaquin <br /> are summarized on individual fact sheets in the remainder of this section.Each fact sheet River under critical(600 cfs)and dry/below normal(1250 cfs)river flows at a permitted <br /> contains information for the following items:data availability,the results of increasing WQCF discharge of 9.87 MGD(ADWF)and at proposed discharges of 17.5 MGD(ADWF)and 27 <br /> discharge from the current permitted 9.87 MGD(ADWF)to the proposed 27 MGD(ADWF),a MGD(ADWF). Improved WQCF treatment processes are projected to produce treated effluent <br /> graphical representation of the estimated change in San Joaquin River concentrations at WQCF having an average BOD concentration of 7 mg/L. <br /> R-3 due to a increase in WQCF discharge,a comparison to applicable water quality objectives or Results: The effect of an increase in WQCF discharge from 9.87 MGD(ADWF)to 27 MGD <br /> criteria,a summary evaluation of the findings of the analysis,and tabularized calculated results (ADWF)is appropriately addressed in the receiving water at well-mixed conditions downstream <br /> of estimated water quality conditions. of the discharge. During critical and dry/below normal San Joaquin River flow conditions,an <br /> increase in WQCF effluent discharge will produce a minor increase in BOD concentrations in the <br /> San Joaquin River downstream of the discharge as shown in Figure 5 and Table 11. A minor <br /> increase in BOD mass loading to the river is also projected. <br /> Biochemical Oxygen Demand(BOD) <br /> 5.8 <br /> J <br /> E 5.5 SJRFlows <br /> 5.4 ■800 cfs <br /> 1111250 cfs <br /> c <br /> � 5.2 <br /> c <br /> 0 <br /> V 5 <br /> 9.87 17.5 27 <br /> WQCF Effluent Flow Rate(MGD) <br /> Figure 5: Projected Change in San Joaquin River Biochemical Oxygen Demand Concentration at <br /> WQCF R3 with increasing WQCF Effluent Flowrate <br /> Comparison to Water Quality Objective: Currently,there is no adopted water quality <br /> objective for BOD in the San Joaquin River. However,the consumptive oxygen demand of <br /> BOD will reduce ambient DO levels in the river,and therefore a nexus exists between BOD and <br /> DO concentrations. The influence of the WQCF BOD input is most strongly expressed as an <br /> oxygen demand downstream of the City's wastewater outfall,and therefore the impact of WQCF <br /> effluent BOD levels in the San Joaquin River is addressed in the Far-Field Analysis and Results <br /> section of this report in a discussion of far-field DO impacts. This near-field BOD impact <br /> analysis serves as the starting point for the far-field DO impact analysis. Estimated <br /> concentrations of BOD in the San Joaquin River under critical and dry/below normal flow <br /> conditions show a minor increase with an increase in WQCF effluent discharge from 9.87 MGD <br /> (ADWF)to 27 MGD(ADWF). The incremental change in BOD concentration in the river is <br /> City of Manteca Antidegradation Analysis 33 June 2007 City of Manteca Antidegradation Analysis 34 June 2007 <br />