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and high hardness)that mitigate toxicity of aluminum to aquatic life. The criterion was <br /> Aluminum,Total developed based on a study conducted for striped bass and brook trout that was low in pH and <br /> hardness. The City has recently completed a WER study as a means of identifying an <br /> 1000 appropriate water quality objective for aluminum in the San Joaquin River that is both <br /> z 800 SJR Flows <br /> sufficiently protective of aquatic life and identifies available assimilative capacity for aluminum <br /> in the river under which the WQCF can discharge its effluent. Regardless,an increase in <br /> `0 600 Itttttt�600 cfs permitted discharge capacity from 9.87 MGD(ADWF)to 27 MGD(ADWF)does not negatively <br /> iiiiiiiim 1250 cis impact the San Joaquin River,and in fact will decrease total aluminum concentrations in the <br /> E 400 WQQ receiving water. <br /> c 200 <br /> 0 <br /> v 0 Table 13: Estimated Impact of Total Aluminum from WQCF Discharge in the San Joaquin River at <br /> 9.87 17.5 27 WQCF R.9 <br /> WQCF Effluent Flow Rate(MGD) Aluminum,Total San Joaquin River Manteca WQCF Effluent <br /> R-1 50th%concen.(pg/L)* 785.1 Flowrate(cfs) Flowrate(MGD ADWF) <br /> ( y)Projected effluent concen.(pg/L) 150 600 1250 9.87 17.5 27 <br /> with increasing WQCF Effluent Flowrate <br /> Figure Projected Change in San Joaquin River Total Aluminum Concentration at WQCF R-3 Est.mass loadinglbs/da 2,539 5,290 12.3 21.9 33.8 <br /> Est.downstream R-3 river concentration(pg/[-)at 600 cfs 769.3 757.6 743.7 <br /> Comparison to Water Ouality Objective: The U.S.EPA chronic ambient water quality Est.downstream R-3 river concentration(pg/L)at 1250 cfs 777.4 771.6 764.5 <br /> criterion for total aluminum,which is often used by the Regional Water Board to interpret the *501"percentile statistic calculated using the following data set: <br /> narrative toxicity objective contained in the Basin Plan,is 87 pg/L. The WER study(City of Data Period:January 2002—September 2004;Sample Size,n=14;Percent Detected Data=100% <br /> Manteca,2007)recently completed by the City for the purpose of identifying an appropriate SSO <br /> for total aluminum in the San Joaquin River indicates that a WER of 22.7 in scientifically <br /> defendable. To this end,the next lowest water quality standard for aluminum(Title 22 <br /> Secondary Maximum Contaminant Level(MCL)of 200µg/L)may be applicable to WQCF <br /> effluent. Title 22 Secondary MCLs are set to evaluate potable water that has received treatment, <br /> including filtration that generally removes the particulate materials from the water,leaving <br /> essentially only the dissolved fraction. However,Title 22 standards do not directly specify <br /> whether the total or dissolved phase should be considered. Applying Secondary MCLs directly <br /> to surface water warrants consideration in that only the dissolved fraction would ultimately pass <br /> through a drinking water treatment plant. The Regional Water Board has requested an opinion <br /> from the California Department of Health Services(DHS)as to whether Secondary MCLs <br /> should be applied to the total or dissolved fraction in receiving waters. DHS responded stating <br /> that application of Secondary MCLs as dissolved is sufficient to protect municipal and drinking <br /> water users. The Regional Water Board has indicated that only the numbers from the Tables of <br /> Title 22 Secondary MCLs are incorporated into the Basin Plan by reference,and will continue to <br /> apply the value of the Secondary MCL standard to the total concentration of the constituent in <br /> the receiving water to provide protection for persons directly using the river as their water <br /> source. <br /> Evaluation: The current U.S.EPA chronic water quality criterion for total aluminum as applied <br /> to the San Joaquin River is believed to be over restrictive and over protective of beneficial uses <br /> because the criterion does not take into account the local water quality characteristics(high pH <br /> z Letter from Carl Lischeske,DHS Region Chief,to Kenneth Landau,Region 5 Assistant Executive Officer, <br /> regarding Yuba City Wastewater Treatment Plant,dated April 10,2007. <br /> City of Manteca Antidegradation Analysis 39 June 2007 City of Manteca Antidegradation Analysis 40 June 2007 <br />