SITE INFORMATION AND CORRESPONDENCE_2005-CURRENT

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September 30, 2004. The resolution adopted the staff report for the periodic review of the 1995 Delta Plan and affirmed the plan as it currently exists until changed by action of the State Board. In adopting the staff report, the State Board accepted the recommendation to receive further information to help decide whether to amend several provisions of the plan, including the southern Delta EC objectives. The State Board also accepted the staff recommendation to consider amending the Program of Implementation section of the plan as necessary for implementation of any changes to the EC water quality objectives for the southern Delta or other revised objectives. (State Board Resolution No. 2004-0062,pp. 1 and 2.)11 Our review of the documents discussed above leads to several conclusions regarding the southern Delta EC objectives from the 1991 and 1995 Delta Plans and the effluent limitations in the City's permit that were adopted by the Regional Board to implement those objectives. First, the lengthy record of prior State Board decisions and water quality control plans for the Delta establishes that the salinity problems in the southern Delta are the result of many inter-related conditions, including water diversions upstream of the Delta, water diversions within the Delta for export and local use, high levels of salinity in irrigation return flows discharged to Delta waterways and tributaries, groundwater inflow, seasonal flow variations, and tidal conditions. Second, although discharge of treated wastewater to the Delta or its tributaries under an NPDES permit can affect EC in the southern Delta, previous State Board decisions and water quality control plans do not discuss treated effluent discharges as a source of salinity in the southern Delta. Similarly, previously adopted implementation programs for complying with the EC objectives in the southern Delta have focused primarily on providing increased flows and reducing the quantity of salts delivered to the Delta and its tributaries by irrigation return flows and groundwater. The record also establishes that the implementation date for actions to implement the 0.7 mmhos/cm EC objective for April through August has been repeatedly postponed and that the State Board recently adopted a report recommending review of southern Delta EC objectives. Revised Water Right Decision 1641 places primary responsibility for meeting the EC objectives on the Department of Water Resources and the Bureau of is The staff report adopted in State Board Resolution No.2004-0062 recommended that the State Board not consider changes to the EC objectives upstream of Vernalis and several other provisions of the 1995 Delta Plan at this time. (State Board Resolution No.2004-0062,p. 2.) 10.