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INFORMATION SHEET OR NO. R5-2004-0028 13 CITY OF MANTECA, CITY LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY for aluminum expressed as total recoverable are 750 ug/l (1-hour average) and 87 ug/1 (4-day average), and are appropriate to implement the narrative toxicity objective. Since both the receiving water and the effluent exceed USEPA's ambient water quality criteria and the secondary MCL,no dilution can be granted. The effluent has the reasonable potential to cause or contribute to an in-stream excursion above water quality objectives for aluminum. Therefore, this Order includes an effluent limitation for Aluminum of 71 ug/l as a 30-day average and 143 ug/l as the daily maximum. The monitoring data are included in Table 3 and the effluent limitation calculations are included in Table 6. 9.4 Iron Iron concentrations in the effluent ranged from 170-730 ug/1 while background concentrations in the San Joaquin River ranged from 780-2800 ug/1 based on results from 12 samples collected between January 2002 and December 2002. The Basin Plan chemical constituents objective includes a receiving water objective in Table III-1 for iron of 300 ug/1 in the Delta, and the secondary MCL for iron of 300 ug/1. Both the receiving water and the effluent exceed the Basin Plan numeric objective and the secondary MCL. Water quality based effluent limitations are included in this Order based on the Basin Plan chemical constituents objective. The data are included in Table 3 and the effluent limitation calculations in Table 6. 9.5 Manganese Manganese concentrations in the effluent ranged from 13-120 ug/1 while background concentrations in the San Joaquin River ranged from 82-220 ug/1 based on results from 11 samples collected between January 2002 and December 2002. The Basin Plan chemical constituents objective includes a receiving water objective in Table III-1 for manganese of 50 ug/1 in the Delta, and the secondary MCL for manganese of 50 ug/l. Both the receiving water and the effluent exceed the Basin Plan numeric objective and the secondary MCL. Water quality-based effluent limitations are included in this Order based on the Basin Plan chemical constituents objective. The data is included in Table 3 and the effluent limitation calculations in Table 6. 9.6 Methylene blue active substances (MBAS) The effluent contains MBAS at levels that may cause or contribute to exceedances in the receiving waters of water quality objectives in the Basin Plan. The Basin Plan includes the"Chemical Constituents"objective that incorporates state MCLS that applies to waters designated MUN. MUN is a designated beneficial use of the San Joaquin River. The Secondary MCL Consumer Acceptance Limit is 500 ug/l for foaming agents (MBAS). The Basin Plan also includes water quality objectives that water not contain floating material or taste- or odor-producing substances in concentrations that causes nuisance or adversely affect beneficial uses. The Basin Plan identifies non-contact water recreation,which includes aesthetic enjoyment, as a beneficial use of the San Joaquin River. MBAS concentrations in excess of the Secondary MCL produce aesthetically undesirable froth, taste, and odor. Foam has been observed on the surface of the discharge plume from the WQCF. MBAS was detected in an effluent sample collected 13 June 2002 at a concentration of 1,800 ug/l. The maximum observed upstream receiving water MBAS concentration is less than 20 ug/l. These data were used in