SITE INFORMATION AND CORRESPONDENCE_CASE 2

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REGIONAL WATER BOARD RESPONSE (SWKCEUOc(;t ne A-1d46(a) and A-1 e4b(b)) -b- PETITIONS FOR REVIEW OF W = DISCHARGE REQUIREMENTS J ORDER NO. R5-2007-0036 (NPD,oNO. CA0079154) AND TIME SCHEDULE ORDER NO. R5-2007-0037 CITY OF TRACY, WASTEWATER TREATMENT PLANT An antidegradation analysis is only required for those constituents that will significantly increase in concentration or mass loading.Z The Order and Fact Sheet include extensive antidegradation findings, even though there will be no lowering of water quality, with the possible exception of minimal (insignificant) increases in mass loadings for a few constituents (see Table F-1, pg F-9). Table F-1 indicates whether an increase is considered by the Regional Water Board to be significant. Although the projected "percent' mass increases appear to be large for some constituents (e.g. 54% - 114%), the corresponding "mass loading" increases are very small (e.g. typically on the order of 0.01 lbs/day). Furthermore, the effluent concentrations for these constituents are well below water quality standards, and the discharge will not cause or contribute to an exceedance of water quality standards in the receiving water or impact beneficial uses. For these reasons, the increases have been determined by the Regional Water Board to be insignificant. The federal antidegradation policy, where it applies, does not prohibit all changes in water quality, but requires that changes be justified based on a three-part test. The first part of the test is that existing instream uses must be maintained, i.e., that the discharge will not cause an exceedence of water quality standards. The Order requires compliance with applicable federal technology- based standards and with effluent limits where the discharge could have the reasonable potential to cause or contribute to an exceedance of water quality standards. Therefore, the Order will protect existing instream uses. The second part of the test is that degradation of high quality waters is allowed if the state finds that allowing lower water quality is necessary to accommodate important economic or social development in the area in which the waters are located, which is a balancing test. In this case, as documented in the Fact Sheet, the City of Tracy is growing and continued treatment of its wastewater is necessary to protect water quality and accommodate growth. The Regional Water Board does not have the jurisdiction to control growth in the City of Tracy', but is required to assure that the discharge is adequately treated. Tertiary and advanced wastewater treatment required by the Order is a very high level of treatment. As demonstrated in the Fact Sheet at.pages F-7 to F-9, the discharge will result in insignificant additional impacts on water quality. The Fact Sheet contains detailed information about each constituent of concern in the waste discharge and what changes in the discharge may occur for each constituent. Table F-1 in the Fact Sheet lists the pollutants of concern and the corresponding effluent concentrations and mass loadings. The effluent concentrations for all constituents will remain the same or decrease. Mass concentrations for some constituents will increase only very slightly and for some there will be a decrease. In the case of oxygen demanding substances (e.g. BOD, ammonia, nitrate, and nitrite) the concentration and mass will be decreased significantly due to increased treatment. The accommodation of the development, as set forth in the federal antidegradation policy and in the Water Code (see Water Code section 13241(e)), justifies lowering of receiving water quality. In this case, The Region 9 Guidance only requires an antidegradation analysis where water quality will be significantly lowered, as determined under state law. (See, e.g., pp. 5, 7, 10.) Although the Regional Water Board could refuse to permit expansion of the facility, that would be as likely to adversely impact water quality due to inadequate treatment, than to prevent growth.