SITE INFORMATION AND CORRESPONDENCE 1980-1999

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FACT SHEET, ATTACHMENT C • ' -2- WASTE DISCHARGE REQUIREMENTS ORDER NO. 2000-**** CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY Receiving Water Dissolved Oxygen Monitoring Results (Monthly Average), and - Number of Samples less than 5 mg/1 Date Flow BOD R-1 R-2 R-3 R-4 (mgd) (lb/day) (mg/1) (Mg/l) (mg/1) (mg/1) Jan 97 5.8 532 4.2' (9 of 9)z 7.1 (1 of 9) 8.4 (0 of 9) 4.7 (5 of 9) Feb 97 5.6 467 5.6 (2 of 8) 8.0 (1 of 8) 9.1 (0 of 8) 6.2 (2 of 8) Mar 97 . 5.5 440 5.7 (0 of 4) 11.5 (0 of 4) 11.0 (0 of 4) 10.5 (0 of 4) Apr 97 5.5 367 . 5.7 (1 of 6) 10.6 (0 of 6) 11.1 (0 of 6) 9.4 (0 of 6) May 97 5.6 411 6.2 (0 of 1) 12.2 (0 of 1) 10.8 (0 of 1) 1.5 (0 of 1) Jun 97 0 --- --- --- --- _-- --_ Jul 970 --- --- --- -_- --_ Aug 97 5.7 295 5.1 (2 of 5) 8.4 (0 of 5) 8.8 (0 of 5) 7.2 (0 of 5) Sep 97 5.5 239 5.2 (3 of 6) 8.7 (0 of 6) 8.7 (0 of 6) 7.7 (0 of 6) Oct 97 5.3 177 5.9 (0 of 6) 10.4 (0 of 6) 10.5 (0 of 6) 9.6 (0 of 6) Nov 97 5.5 275 5.2 (1 of 8) 8.6 (0 of 8) 9.3 (0 of 8) 7.0 (0 of 8) Dec 97 5.9 379 5.8 (1 of 10) 10.1 (0 of 10) 10.8 (0 of 10) 9.3 (0 of 10) Jan 98 5.9 492 5.6 (2 of 8) 8.2 (0 of 8) 9.4 (0 of 8) 7.3 (0 of 8) Feb 98 6.3 473 4.4 (7 of 8) 7.4 (0 of 8) 9.0 (0 of 8) 4.9 (5 of 8) Mar 98 5.8 532 5.1 (3 of 9) 9.1 (0 of 9) 10.0 (0 of 9) 6.7 (1 of 9) Apr 98 5.6 514 5.1 (4 of 9) 11.8 (0 of 9) 11.0 (0 of 9) 9.9 (0 of 9) May 98 5.6 448 52 (4 of 8) 105 (0 of 8) 89 (0 of 8) 97 (0 of 8) 1 Monthly average dissolved oxygen concentration 2 Number of individual samples with dissolved oxygen concentrations less than 5 mg/l compared to the total number of samples collected. The data shows that at the current discharge rate of less than 6 mgd, corresponding to a BOD loading of up to 5321b/day, the dissolved oxygen in Dredger Cut(R-1) does not meet the Basin Plan objective for dissolved oxygen of 5 mg/1 in 39% of samples collected when discharge was occurring, whereas it is usually met further downstream below the confluence with Bishop Cut and White Slough (R-2 and R-3). The discharge is causing or contributing to the violations. Studies completed to date indicate that the discharge of 8.5 mgd of secondary-treated effluent may cause violations of the dissolved oxygen objective to also occur in White Slough and Bishop Cut. This Order includes more stringent effluent limits for BOD than were imposed in the past. This alone will not prevent excursions of the dissolved oxygen objective in Dredger Cut. Therefore, this Order also requires the Discharger to maximize land disposal of effluent, and prohibits discharges when dissolved oxygen concentrations in Dredger Cut are less than 5 mg/l. The Discharger is not currently capable of meeting these requirements. It follows from the preceding paragraph that effluent dissolved oxygen content must also be limited to prevent discharges that would immediately place the receiving water at an unacceptable dissolved oxygen level. Therefore, this Order requires an effluent dissolved oxygen concentration to be 5.0 mg/1 or greater when conditions allow and surface water discharge takes place.