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INFORMATION SHEET ORDER NO.R5-2004-0028 11 INFORMATION SHEET ORDER NO.R5-2004-0028 12 CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY SAN JOAQUIN COUNTY average(acute)concentration to implement the narrative toxicity objective. Therefore,this Order provide municipal water supply with an acceptable TDS,any increase in salt concentration effectively includes water quality based effluent limitations for chlorine based on the USEPA ambient criteria to reduces the available water supply in Southern California(Metropolitan Water District of Southern protect freshwater aquatic life. California,Salinity Management Study,1998). The WQCF outfall is a side bank discharge to the San Joaquin River. The chlorine residual limitations required in this Order are protective of aquatic organisms in the undiluted discharge. Because of this, Chloride concentrations in the effluent ranged from 100-230 mg/1 with an average of 138 mg/I based the Regional Board does not anticipate residual chlorine impacts to benthic organisms if compliance is on 16 samples collected during 2002. Background concentrations in the San Joaquin River ranged maintained. from 51-170 mg/1 with an average of 98 mg/l based on results from eleven samples collected during 2002. Both the receiving water and the effluent exceed the agricultural use-protective water quality 9.2 Salinity limit of 106 mg/l,based on the narrative objective. The discharge contains total dissolved solids(TDS),chloride and electrical conductivity. These are Electrical conductivity(EC)shows reasonable potential to exceed water quality objectives in both the water quality parameters that are typically indicative of the salinity of the water. Their presence in effluent and in the receiving water. A review of the Discharger's monitoring reports from January water can be growth limiting to certain agricultural crops and can affect the taste of the water for 1998 through December 2002 shows the annual average effluent EC is 1099 umhos/cm,the lowest human consumption. There are no USEPA water quality criteria for protection of aquatic organisms monthly average is 819 umhos/cm,and the highest monthly average is 1300 umhos/cm. These levels for these constituents. The Basin Plan"Chemical Constituent"objective incorporates state MCLS, exceed the applicable objectives. EC data collected at receiving water sample location RI from contains a narrative objective,and contains numeric water quality objectives for electrical January 2002 through December 2002 show that the conductivity in the receiving water ranged from conductivity. The secondary California maximum contaminant level(MCL)for TDS is 500 mg/1 as a 380 umhos/cm to 1100 umhos/cm and averaged 686 umhos/cm in 12 sampling events. Hourly EC data recommended level,1000 mg/1 as an upper level,and 1500 mg/1 as a short-term maximum. The collected at the Department of Water Resources(DWR)Mossdale monitoring station(RSAN087)from recommended agricultural water quality goal for TDS,that would implement the narrative"Chemical December 2000 through September 2002 show that the conductivity in the San Joaquin River ranged Constituent"objective,is 450 mg/1 as a long-term average based on Water Quality for Agriculture, from 299 umhos/cm to 1131 umbos/cm and averaged 721 umhos/cm. San Joaquin River monitoring Food and Agriculture Organization of the United Nations—Irrigation and Drainage Paper No.29,Rev. for electrical conductivity at Vernalis between 1985 and 1998 showed frequent exceedances of the EC 1(R.S.Ayers and D.W.Westcot,Rome,1985). Water Quality for Agriculture evaluates the impacts water quality objectives(Reference Figure 1-3,Total Maximum Daily Load for Salinity and Boron in of salinity levels on crop tolerance and yield reduction,and establishes water quality goals that are the Lower San Joaquin River(January 2002)). These data show that the receiving water frequently protective of sensitive agricultural uses. The recommended agricultural water quality goal for has no assimilative capacity for EC. An Effluent Limitation for electrical conductivity is included in chloride,that would implement the narrative"Chemical Constituent'objective,is 106 mg/1 based on this Order and is based on the Basin Plan water quality objective for electrical conductivity in the Water Quality for Agriculture,Food and Agriculture Organization of the United Nations—Irrigation South Delta. and Drainage Paper No.29,Rev.1(R.S.Ayers and D.W.Westcot,Rome,1985). The Basin Plan water quality objectives for electrical conductivity for the South Delta are 700 umhos/cm(from 1 April The TDS,chloride,and electrical conductivity objectives and recommended levels are all measures of to 31 August)and 1000 umhos/cm(from 1 September to 31 March). State Board Decision 1641(D- the salt content of the water. Compliance with the Effluent Limitations for electrical conductivity 1641)(water rights)requires that the 1000 umhos/cm objective be met year round until 1 April 2005 at based on the Basin Plan seasonal water quality objectives of 700 umhos/cm and 1000 umhos/cm will which time the seasonal objectives will be effective. be protective of the chloride and TDS recommended levels;therefore,no limitations are included for chloride and TDS. A review of the Discharger's monitoring reports from January 1998 through December 2002 indicates an annual average TDS effluent concentration of 634 mg/1,a lowest monthly average of 540 mg/1,and 9.3 Aluminum a highest monthly average of 727 mg/1. These concentrations exceed the applicable objectives. Limited TDS data collected at receiving water sample location Rl from January 2002 through Aluminum concentrations in the effluent were detected in the range from 70 ug/1 to 350 ug/1 in December 2002 showed a TDS concentration range from 210 mg/1 to 1300 mg/l with an average of sampling conducted in 2002. Aluminum was detected in the receiving water(R-1)in the range from 500 mg/1 in 12 sampling events. The Regional Board report Total Maximum Daily Load for Salinity 420 ug/1 to 2200 ug/1 in 12 samples collected between January 2002 and December 2002. Dissolved and Boron in the Lower San Joaquin River(January 2002)presented monthly average TDS data for concentrations of aluminum in the effluent and the receiving water were significantly less than the the San Joaquin River at Vernalis from October 1976 through September 1997. The Vernalis data totals listed above. The Basin Plan's chemical constituents water quality objective prohibits chemical showed a maximum monthly average TDS of 1024 mg/1 with 57 of 252 months having monthly constituents in concentrations that exceed state MCLS or that adversely affect beneficial uses. MUN is averages greater than 500 mg/l. These data indicate that the receiving water frequently exceeds water a beneficial use of the San Joaquin River. The Primary and Secondary MCLS for aluminum are 1000 quality objectives to protect its beneficial uses and lacks assimilative capacity for TDS. As water ug/1 and 200 ug/1 respectively. The Basin Plan contains a narrative toxicity objective. Consistent with exported from the Delta by the State Water Project is,in part,mixed with Colorado River water to 40 CFR 122.44(d),USEPA's Ambient Water Quality Criteria for protection of freshwater aquatic life